bluuebunny/crossref_metadata_2025 huggingface dataset:
Steady-state solutions of one-dimensional competition models in an unstirred chemostat via the fixed point index theory
Authors: Lan Kunquan , Lin Wei
Published: March 2020

The existence and nonexistence of semi-trivial or coexistence steady-state solutions of one-dimensional competition models in an unstirred chemostat are studied by establishing new results on systems of Hammerstein integral equations via the classical fixed point index theory. We provide three ranges for the two parameters involved in the competition models under which the models have no semi-trivial and coexistence steady-state solutions or have semi-trivial steady-state solutions but no coexistence steady-state solutions or have semi-trivial or coexistence steady-state solutions. It remains open to find the largest range for the two parameters under which the models have only coexistence steady-state solutions. We apply the new results on systems of Hammerstein integral equations to obtain results on steady-state solutions of systems of reaction-diffusion equations with general separated boundary conditions. Such type of results have not been studied in the literature. However, these results are very useful for studying the competition models in an unstirred chemostat. Our results on Hammerstein integral equations and differential equations generalize and improve some previous results.
Dreaming partnership, enabling inequality: administrative infrastructure in global health science
Authors: Crane Johanna T.
Published: March 2020

This article examines the fiscal and administrative infrastructures underpinning global health research partnerships between the US and Uganda, and the power dynamics they entail. Science studies scholars and anthropologists have argued for the importance of studying so-called ‘boring things’ – standards, bureaucracies, routinization, codes and databases, for example – as a way to bring to the surface the assumptions and power relations that often lie embedded within them. This article focuses on fiscal administration as an understudied ethnographic object within the anthropology of global health. The first part of the article is a case study of the fiscal administration of a US–Uganda research partnership. The second part describes the institutionalization of some of the administrative norms and practices used by this partnership within the ‘global health enabling systems’ employed by US universities working in Uganda and elsewhere in Africa. I analyse a case study and ‘enabling systems’ to show how these administrative strategies create parallel infrastructures that avoid direct partnership with Ugandan public institutions and may facilitate the outsourcing of legal and financial risks inherent in international partnerships to Ugandan collaborators. In this way, these strategies act todisablerather thanenable(or build) Ugandan research and institutional capacity, and have profound implications for African institutions as well as for the dream of ‘real partnership’ in global health.
Apartheid South Africa's segregated legal field: black lawyers and the Bantustans
Authors: Gibbs Timothy
Published: March 2020

The history of South Africa's urban-based ‘struggle lawyers’ – a trajectory epitomized by Nelson Mandela – is much discussed by historians and biographers, reflecting a broader vein of historiography that celebrates anti-colonial legal activism. However, it was South Africa's ‘Native Reserves’ and Bantustans that produced the majority of African lawyers for much of the twentieth century. Indeed, two-thirds of the African justices who have sat on the post-apartheid Constitutional Court either practised or trained in the Bantustans during the apartheid era. The purpose of this article is thus to reappraise South Africa's ‘legal field’ – the complex relationship between professional formation, elite reproduction and the exercise of political power – by tracing the ambiguous role played by the Native Reserves/Bantustans in shaping the African legal profession across the twentieth century. How did African lawyers, persistently marginalized by century-long patterns of exclusion, nevertheless construct an elite profession within the confines of segregation and apartheid? How might we link the histories of the Bantustans with the better-known ‘struggle historiography’ that emphasizes the role of political and legal activism in the cities? And what are the implications of South Africa's segregated history for debates about the ‘decolonization’ of the legal profession in the post-apartheid era?
Janus-faced activists: the social and political embeddedness of civil society in Niger
Authors: Schritt Jannik
Published: March 2020

This article discusses the workings of civil society and its leaders in Niger. Tracing the country's historically sedimented socio-political order, it argues that Niger's civil society is characterized by a twofold embeddedness. Since the introduction of multiparty politics in 1990, the political game in Niger has been exemplified by co-optation, bribery and corruption. These spoils are a central focus for civil society leaders who have become experienced in the political game. Indeed, actors’ social embeddedness in networks of solidarity demands that they capture and redistribute the spoils they receive. At the same time, however, their social and political legitimacy as civil society leaders rests on their ability to avoid becoming entangled in the game, and to avoid accusations of ‘playing politics’. In other words, civil society activists are embedded in the same social and political structures as state bureaucrats and politicians. In this context, civil society activists cannot maintain the moral high ground they often claim to occupy.
ON THE HARMONIC ZYGMUND SPACES
Authors: ALJUAID MUNIRAH , COLONNA FLAVIA
Published: March 2020

In this paper we study a class ${\mathcal{Z}}_{H}$ of harmonic mappings on the open unit disk $\mathbb{D}$ in the complex plane that is an extension of the classical (analytic) Zygmund space. We extend to the elements of this class a characterisation that is valid in the analytic case. We also provide a similar result for a closed separable subspace of ${\mathcal{Z}}_{H}$ which we call the little harmonic Zygmund space.
The importance of constraints on constraints
Authors: Bates Christopher J. , Sims Chris R. , Jacobs Robert A.
Published: March 2020

The “resource-rational” approach is ambitious and worthwhile. A shortcoming of the proposed approach is that it fails to constrain what counts as a constraint. As a result, constraints used in different cognitive domains often have nothing in common. We describe an alternative framework that satisfies many of the desiderata of the resource-rational approach, but in a more disciplined manner.
Sampling as a resource-rational constraint
Authors: Sanborn Adam N. , Zhu Jianqiao , Spicer Jake , Chater Nick
Published: March 2020

Resource rationality is useful for choosing between models with the same cognitive constraints but cannot settle fundamental disagreements about what those constraints are. We argue that sampling is an especially compelling constraint, as optimizing accumulation of evidence or hypotheses minimizes the cost of time, and there are well-established models for doing so which have had tremendous success explaining human behavior.
Projectile energy dependence of L X-ray emission in collisions of Xe23+ with In target: role of Coulomb ionization and quasi-molecular effects
Authors: Ren Jieru , Zhao Yongtao , Ma Wencai , Wang Xing , Liu Yu , Hu Pengfei , Cheng Rui , Zhou Xianming , Wang Yuyu , Lei Yu , Chen Yanhong , Xiao Guoqing
Published: March 2020

The X-ray emissions in the interaction of 3–6 MeV Xe23+ ions into thick solid In target are measured. The projectile-to-target and target Lα/Lβ X-ray production intensity ratios are observed to strongly depend on the projectile energy. The dependence deviates from Coulomb ionization predictions, which implies the important roles of coupling between subshells and the activation of 4fσ rotational couplings for projectile energy larger than 5 MeV.
A Review of Dynamic Balancing for Robotic Mechanisms
Authors: Wei Bin , Zhang Dan
Published: March 2020

The authors summarize the main dynamic balancing methods of robotic mechanisms in this paper. The majority of dynamic balancing methods have been presented, and there may be other dynamic balancing methods that are not included in this paper. Each of the balancing methods is reviewed and discussed. The advantages and disadvantages of each method are presented and compared. The goal of this paper is to provide an overview of recent research in balancing. The authors hope that this study can provide an informative reference for future research in the direction of dynamic balancing of robotic mechanisms.
ENTROPY-BASED AND NON-ENTROPY-BASED GOODNESS OF FIT TEST FOR THE INVERSE RAYLEIGH DISTRIBUTION WITH PROGRESSIVELY TYPE-II CENSORED DATA
Authors: Ma Yanbin , Gui Wenhao
Published: March 2020

In this paper, the problem of goodness of fit test for the inverse Rayleigh distribution based on progressively Type-II censored samples is studied. We develop two test statistics via entropy and propose one new non-entropy test statistic via a pivotal method. We also study the properties of these test statistics. Critical values are obtained by simulations. Then, we do power analysis of these test statistics against various alternatives under different censoring schemes. We conclude that the tests we proposed perform well against various alternatives, especially for non-monotone hazard alternatives. Finally, one real data set is analyzed.
The development of a theoretically derived measure exploring extreme appraisals of sleep in bipolar disorder: a Delphi study with professionals
Authors: Pearson Lydia , Parker Sophie , Mansell Warren
Published: March 2020

Background:

Sleep and mood are known to be linked and this is particularly evident in people with a diagnosis of bipolar disorder (BD). It has been proposed that psychological interventions improving sleep can be a pathway for improving mood. In order for a psychological sleep intervention to be appropriate, the common cognitive processes maintaining the range of sleep disturbances need to be investigated.

Aim:

This study aimed to explore and identify expert consensus on positive and negative sleep appraisals in the context of low and high mood states, using the Integrative Cognitive Model as a theoretical guide.

Method:

A Delphi approach was utilized to allow clinical and research professionals, with experience in the field of BD, to be anonymously consulted about their views on sleep appraisals. These experts were invited to participate in up to three rounds of producing and rating statements that represented positive and negative sleep appraisals.

Results:

A total of 38 statements were developed and rated, resulting in a final list of 19 statements that were rated as ‘essential’ or ‘important’ by >80% of the participants. These statements represent the full range of extreme sleep appraisals this study had set out to explore, confirming the importance of better understanding and identifying positive and negative sleep cognitions in the context of high and low mood.

Conclusion:

The statements reviewed in this study will be used to inform the development of a sleep cognition measure that may be useful in cognitive therapy addressing sleep disturbances experienced along the bipolar spectrum.
Conversion in English: homonymy, polysemy and paronymy
Authors: VALERA SALVADOR , RUZ ALBA E.
Published: March 2020

Conversion is a key type of word-formation process in English, but the precise nature of the relation between base and derivative in conversion is rarely discussed, even if conversion is considered as a dynamic process. When it is considered explicitly, the relation has been described in terms of paradigmatic relations between lexemes, specifically homonymy or polysemy. This is usually without any specification of how converted words accommodate the conditions set by the definition of each of these relations, and as a special type of one or the other, because conversion-related words violate some of those conditions. This article is intended as a systematic review of the literature that discusses the relation between conversion-related words in English. We show that a wide range of proposals have been made to describe the relation: homonymy, heterosemy, homomorphy, zero-derivation (as a relation), polysemy, lexical extension, synsemy, hyponymy and paronymy. We review the extent to which each of these terms fits the relationship in major types of conversion, and argue that, if a relationship is to be described between conversion-related pairs, then Cruse's (1986) separation of semantic relations of a paradigmatic type from paronymic relations is of special relevance here. We propose that, regardless of the direction and type of meaning, paronymy applies across the various specific semantic patterns that conversion may involve. We emphasize, however, the possibility of several relations according to the type of conversion, i.e. different types of conversion may need description in terms of a different relation.
Examining school-level implementation of British Columbia, Canada’s school food and beverage sales policy: a realist evaluation
Authors: Levay Adrienne V , Chapman Gwen E , Seed Barb , Wittman Hannah
Published: March 2020

Objective:

To identify key school-level contexts and mechanisms associated with implementing a provincial school food and beverage policy.

Design:

Realist evaluation. Data collection included semi-structured interviews (n 23), structured questionnaires (n 62), participant observation at public events (n 3) and scans of school, school district and health authority websites (n 67). The realist heuristic, context + mechanism → outcome configuration was used to conduct the analysis.

Setting:

Public schools in five British Columbia (BC), Canada school districts.

Participants:

Provincial and regional health and education staff, private food vendors and school-level stakeholders.

Results:

We identified four mechanisms influencing the implementation of BC’s school food and beverage sales policy. First, the mandatory nature of the policy triggered some actors’ implementation efforts, influenced by their normative acceptance of the educational governance system. Second, some expected implementers had an opposite response to the mandate where they ignored or ‘skirted’ the policy, influenced by values and beliefs about the role of government and school food. A third mechanism related to economics demonstrated ways vendors’ responses to school demand for compliance with nutritional Guidelines were mediated by beliefs about food preferences of children, health and food. The last mechanism demonstrated how resource constraints and lack of capacity led otherwise motivated stakeholders to not implement the mandatory policy.

Conclusion:

Implementation of the food and beverage sales policy at the school level is shaped by interactions between administrators, staff, parent volunteers and vendors with contextual factors such as varied motivations, responsibilities and capacities.
The Enduring, Gilded Periphery: Colonialism and Grand Cayman in Capital's Atlantic World
Authors: Connolly N. D. B.
Published: March 2020

The man they called “Smiley” died in February 1938 on an operating table in Kingston, Jamaica. His stomach cancer, only recently discovered, was quickly deemed inoperable by a doctor in the Cayman Islands, where he lived with his pregnant wife and four children. In Cayman, there had been no public hospital. Instead, a British heiress paid to build a four-bed emergency ward and dispensary meant to serve the island's 6,500 residents. Four beds for more than six thousand. Such insufficiency represented the extent of institutionalized health care at the edge of the British Empire.
The chemical feature of Miras in 47 Tuc based on the WINERED spectra
Authors: Wang Y. , D’Orazi V. , Matsunaga N. , Bono G.
Published: March 2020

Variable stars are good stellar tracers. Among various variables, Miras have long periods and are at the evolutionary phase of asymptotic giant branch. Their low effective temperatures lead to a difficulty to determine their chemical composition that since plenty of molecular bands exist in their spectra which even blocks the identifition of metallic lines. However, molecular features are less common in near-infrared (NIR) compared with other wavelength ranges. Here we take advantage of the high-resolution (R ~ 28, 000) spectra obtained with WINERED, which is a NIR spectrograph covering the wavelength range of 0.91–1.35 μm, to analyze and determine the chemical abundances of three Miras in the Galactic globular cluster 47 Tuc (NGC 104). Steps of data reduction and analysis, as well as part of the preliminary results, are briefly shown.
Globular clusters in the era of precision astrometry
Authors: Bianchini Paolo
Published: March 2020

he study of the kinematics of globular clusters (GCs) offers the possibility of unveiling their long term evolution and uncovering their yet unknown formation mechanism. Gaia DR2 has strongly revitalized this field and enabled the exploration of the 6D phase-space properties of Milky Way GCs, thanks to precision astrometry. However, to fully leverage on the power of precision astrometry, a thorough investigations of the data is required. In this contribution, we show that the study of the mean radial proper motion profiles of GCs offers an ideal benchmark to assess the presence of systematics in crowded fields. Our work demonstrates that systematics in Gaia DR2 for the closest 14 GCs are below the random measurement errors, reaching a precision of ∼0.015 mas yr−1 for mean proper motion measurements. Finally, through the analysis of the tangential component of proper motions, we report the detection of internal rotation in a sample of ∼50 GCs, and outline the implications of the presence of angular momentum for the formation mechanism of proto-GC. This result gives the first taste of the unparalleled power of Gaia DR2 for GCs science, in preparation for the subsequent data releases.
Hydrodynamic simulations of second generation star formation in a young globular cluster
Authors: Calura Francesco
Published: March 2020

I will present results obtained by means of three-dimensional hydrodynamic simulations of the formation of second generation (SG) stars in a young globular cluster (GC). Our setup includes the mass return from Asymptotic Giant branch (AGB) stars, the accretion of pristine gas as well as star formation of SG stars, three ingredients which have never been simultaneously taken into account in previous 3D numerical studies of GC formation. The cluster is set in motion with respect to a distribution of gas and allowed to accrete mass from it. Formation of SG stars occurs out of the gas shed by AGB stars and from the gas accreted during the motion of the cluster. We consider two models characterised by different densities of the external gas. In both cases, we find that a very compact SG subsystem with central density > 105M⊙/pc3 forms in the innermost regions of the cluster.
Radial distribution of Blue Stragglers in NGC 5466 using AstroSat
Authors: Sahu Snehalata , Subramaniam Annapurni
Published: March 2020

We present the results obtained from Near-UV observations of the cluster NGC 5466 taken with UVIT onboard AstroSat to study the radial distribution of Blue Straggler Stars (BSSs), covering the cluster region up to a radius of 14'. Our study confirms that the BSSs are more centrally concentrated than Horizontal Branch (HB) stars in the cluster. We do not find a statistically significant rising trend in the radial distribution of BSSs for the outer regions, as most of the previously catalogued BSSs that are located in the cluster outskirts were found to be non-members, quasars or galaxies. This study highlights the importance of UV imaging combined with membership information to probe the radial distribution of BSSs.
The tidal tails of open star clusters produced by early gas expulsion
Authors: Dinnbier František , Kroupa Pavel
Published: March 2020

We investigate, for the first time, the formation and evolution of the tidal tail released from a young Pleiades-like star cluster due to expulsion of primordial gas in a realistic gravitational field of the Galaxy. The tidal tails (as well as clusters) are integrated by nbody6 from their embedded phase for more than 300 Myr. We vary the star formation efficiency (SFE) from 33% to 100% and the timescales of gas expulsion as free parameters, and provide predictions for the morphology and kinematics of the evolved tail for each of the models. The resulting tail properties are intended for comparison with Gaia measurements, where an inverse analysis of our findings might constrain some of the poorly understood conditions and processes in embedded star clusters during the gas phase and gas expulsion.
Dynamical evolution of star clusters with top-heavy IMF
Authors: Haghi Hosein , Safaei Ghasem , Zonoozi Akram H. , Kroupa Pavel
Published: March 2020

Several observational and theoretical studies suggest that the initial mass function (IMF) slope for massive stars in globular clusters (GCs) depends on the initial cloud density and metallicity, such that the IMF becomes increasingly top-heavy with decreasing metallicity and increasing the gas density of the forming object. Using N-body simulations of GCs starting with a top-heavy IMF and undergo early gas expulsion within a Milky Way-like potential, we show how such a cluster would evolve. By varying the degree of top-heaviness, we calculate the dissolution time and the minimum cluster mass needed for the cluster to survive after 12 Gyr of evolution.
Phase space complexity of star clusters: Fresh observables for old and new questions
Authors: Lisa Varri Anna , Breen Philip G. , Heggie Douglas C.
Published: March 2020

The blooming era of precision astrometry for Galactic studies truly brings the rich internal dynamics of globular clusters to the centre stage. But several aspects of our current understanding of fundamental collisional stellar dynamics cannot match such new-generation data and the theoretical ambitions they trigger. This rapidly evolving context offers the stimulus to address a number of old and new questions concerning the phase space properties of this class of stellar systems.
Unexpectedly high formation rate of merging binary black holes in open clusters
Authors: Kumamoto Jun , Fujii Michiko S. , Tanikawa Ataru
Published: March 2020

Gravitational wave direct detections suggest that 30 M⊙ binary black holes (BBHs) commonly exist in the universe. One possible formation scenario of such BBHs is dynamical three-body encounters in dense star clusters. We performed a series of direct N-body simulations with a mass of 2500 and 10000 M⊙ and found a new channel for the formation of BBHs which is dominant in open clusters. In open clusters, the core-collapse time is shorter than in globular clusters, and therefore massive main-sequence (MS) binaries can form before they evolve to BHs. These MS binaries experience common envelope evolution and evolve to hard BBHs, which can merge within the Hubble time. The number of BBH mergers per unit mass obtained from our simulations reached 20–50 % of that for globular clusters, assuming an initial cluster mass function. Thus, open clusters can be a dominant formation site of hard BBHs.
Chemical and kinematic study of Large Magellanic Cloud RGB stars
Authors: Minelli Alice , Mucciarelli Alessio
Published: March 2020

The Large Magellanic Cloud (LMC) is the closest massive satellite of the Milky Way (MW), and its proximity allows us to study its stellar populations with great detail, both with resolved photometry and spectroscopy. In turn, this is crucial to unveil its star formation and chemical enrichment histories, and also to investigate the effects that gravitational interactions with other systems (as the Small Magellanic Cloud (SMC) and the MW) may induce on an irregular galaxy. The LMC is characterized by a still on-going star formation activity, as traced by the wide range of ages and metallicities of its stellar populations. However, most of the information about the chemistry and the kinematics of this galaxy has been obtained from low-resolution spectra, which do not allow to draw firm conclusions on many crucial open questions. In particular, (1) we still miss a homogeneous determination of the LMC metallicity distribution; (2) the metal-poor component is still poorly known and described; and (3) we have no conclusive information on the existence of metallicity gradients, which would suggest to spatially inhomegeneous star formation events. To properly address these issues, we analysed nearly 500 high-resolution FLAMES spectra of red giant stars belonging to the LMC field, the largest set of high- resolution spectra of LMC stars analysed so far in a homogeneous way.
Dynamical models of spheroidal multi-component stellar systems
Authors: Caravita Caterina , Ciotti Luca , Pellegrini Silvia
Published: March 2020

. We present a significantly improved version of our numerical code JASMINE, that can now solve the Jeans equations for axisymmetric models of stellar systems, composed of an arbitrary number of stellar populations, a Dark Matter halo, and a central Black Hole. The stellar components can have different structural (density profile, flattening, mass, scale length), dynamical (rotational support, velocity dispersion anisotropy), and population (age, metallicity, Initial Mass Function, mass-to-light ratio) properties. These models, when combined with observations, will allow to investigate important issues, such as quantifying the systematic effects of IMF variations, of mass-to-light ratio gradients, and of different stellar kinematic components (e.g. counter rotating disks, kinematically decoupled cores) on luminosity-weighted properties. The developed analytical and numerical framework aims at modeling Early-Type Galaxies, but it can also be applied to dwarf Spheroidal galaxies and Globular Clusters.
Star clusters of the Andromeda galaxy. Multicolour HST photometry
Authors: Naujalis Rokas , Stonkutė Rima , Vansevičius Vladas
Published: March 2020

We performed a new integrated photometry in six passbands on HST M31 PHAT survey mosaics of 1181 star clusters spread over a large range of radial distance. Due to strongly varying background we interactively determined its level based on image and growth-curve analysis. We derived cluster age, mass, extinction, and metallicity by employing stochastic star cluster models.
Understanding the dynamical status of Galactic Globular Cluster NGC 6656
Authors: Singh Gaurav , Yadav R. K. S.
Published: March 2020

We present the study of horizontal branch morphology of the cluster NGC 6656. A blueward shift in temperature of about ~5000 K (nM-jump) in the color-color plot is detected.To explain this feature, we study the presence of stellar-mass black hole by plotting Projected density profile (PDP) in the central HST region. The PDP in the inner region (r < 10″) can be nicely reproduced by the king+BH model. The blue ward shift in temperature can be due the presence of stellar mass black holes in the centre.
BEANS – distributed data analysis for numerical simulations
Authors: Hypki Arkadiusz , Giersz Mirek , Askar Abbas , Belloni Diogo , Leveque Agostino
Published: March 2020

beans is a tool for distributed data analysis. It provides web and command line interface for data analysis and plotting for huge datasets. beans is written in a general form and can be used in any field of research to analyze the data. The main purpose of beans is to provide to the community a versatile tool to store, analyze and then visualize any amount of scientific data (e.g. numerical simulation, observations).
Extra-tidal features using Gaia DR2
Authors: Carballo-Bello Julio A.
Published: March 2020

In recent years, we have gathered enough evidence showing that most of the Galactic globular clusters extend well beyond their King tidal radii and fill their Jacobi radii in the form of “extended stellar haloes”. In some cases, because of the interaction with the Milky Way, stars are able to exceed the Jacobi radius, generating tidal tails which may be used to trace the mass distribution in the Galaxy. In this work, we use the precious information provided by the space mission Gaia (photometry, parallaxes and proper motions) to analyze NGC 362 in the search for member stars in its surroundings. Our preliminar results suggest that it is possible to identify member stars and tidal features up to distances of a few degrees from the globular cluster center.
The dynamics of the globular cluster M22 (NGC 6656)
Authors: Chen D. , Chen L. , Wang J. J.
Published: March 2020

We have used the Hubble Space Telescope (HST) observations to measure proper motion of the globular cluster NGC 6656 (M22) with respect to the background bulge stars and its internal velocity dispersion profile. Based on the proper motion of the clusters, its space velocity and orbit are also calculated. The central velocity dispersion in radial and tangential components of the internal motion of cluster stars is 16.99 km s−1. We derive the mass-to-light ratio M/LV∼3.3 ± 0.2 which is relatively higher than the previous works.
Supermassive stars as the origin of the multiple populations in globular clusters
Authors: Gieles Mark , Charbonnel Corinne
Published: March 2020

Globular clusters (GCs) display anomalous light-elements abundances (HeCNONaMgAl), resembling the yields of hot-hydrogen burning, but there is no consensus yet on the origin of these ubiquitous multiple populations. We present a model in which a super-massive star (SMS, ≳103 M⊙) forms via stellar collisions during GC formation and pollutes the intra-cluster medium. The growth of the SMS finds a balance with the wind mass loss rate, such that the SMS can produce a significant fraction of the total GC mass in processed material, thereby overcoming the so-called mass-budget problem that plagues other models. Because of continuous rejuvenation, the SMS acts as a ‘conveyer-belt’ of hot-hydrogen burning yields with (relatively) low He abundances, in agreement with empirical constraints. Additionally, the amount of processed material per unit of GC mass correlates with GC mass, addressing the specific mass budget problem. We discuss uncertainties and tests of this new self-enrichment scenario.
Unveiling forming star clusters in the young Universe
Authors: Vanzella E. , Calura F. , Meneghetti M. , Caminha G. B. , Mercurio A. , Castellano M. , Rosati P. , Grillo C. , Sani E. , Cupani G.
Published: March 2020

The identification of young massive star clusters (YMCs) at high redshift is becoming a real fact. We present recent results from Hubble deep imaging and VLT/ MUSE - X-Shooter observations boosted by strong gravitational lensing. We report on two parsec-scale star-forming systems at z = 6.145 and 2.37 (>10 Gyrs of look back time) currently representing the best candidate high-z YMCs. All of this also implies that the search for globular cluster precursors has already begun.
Atmospheric Freshwater Transport From the Atlantic to the Pacific Ocean: A Lagrangian Analysis
Authors: Dey Dipanjan , Döös Kristofer
Published: March 2020

The Atlantic‐to‐Pacific atmospheric freshwater transport was calculated using Lagrangian water mass trajectories. These were decomposed into eastward and westward moving classes, carrying water over Afro‐Eurasia and over America, respectively. The results reveal that the midlatitude westerlies are contributing to midlatitude precipitation in the Pacific Ocean through transporting water mass from the midlatitude Atlantic Ocean over Afro‐Eurasia. In addition, precipitation in the Eastern Tropical Pacific Ocean is found to be associated with the easterly winds carrying water mass from the tropical Atlantic Ocean. A quantitative analysis of the atmospheric freshwater transport furthermore shows that annually, the westerlies carry 0.40 Sv, approximately twice as much water as the easterly trade winds (0.26 Sv) to the Pacific Ocean, but with a strong seasonality. The Atlantic Ocean exports more freshwater across Afro‐Eurasia than across America, except during the June–August periods. The average residence time of this atmospheric water transport is roughly twice as long when it crosses Afro‐Eurasia (54 days) rather than America (24 days).
The Relationship Between Cusp Region Ion Outflows and East‐West Magnetic Field Fluctuations at 4,000‐km Altitude
Authors: Hatch S. M. , Moretto T. , Lynch K. A. , Laundal K. M. , Gjerloev J. W. , Lund E. J.
Published: March 2020

A number of interdependent conditions and processes contribute to ionospheric‐origin energetic (
10 eV to several keV) ion outflows. Due to these interdependences and the associated observational challenges, energetic ion outflows remain a poorly understood facet of atmosphere‐ionosphere‐magnetosphere coupling. Here we demonstrate the relationship between east‐west magnetic field fluctuations (
) and energetic outflows in the magnetosphere‐ionosphere transition region. We use dayside cusp region FAST satellite observations made near apogee (
4,180‐km altitude) near fall equinox and solstices in both hemispheres to derive statistical relationships between ion upflow and
spectral power as a function of spacecraft frame frequency bands between 0 and 4 Hz. Identification of ionospheric‐origin energetic ion upflows is automated, and the spectral power
in each frequency band is obtained via integration of
power spectral density. Derived relationships are of the form
for upward ion flux
at 130‐km altitude, with
the mapped upward ion flux for a nominal spectral power
 nT
. The highest correlation coefficients are obtained for spacecraft frame frequencies
0.1–0.5 Hz. Summer solstice and fall equinox observations yield power law indices
0.9–1.3 and correlation coefficients
, while winter solstice observations yield
0.4–0.8 with
. Mass spectrometer observations reveal that the oxygen/hydrogen ion composition ratio near summer solstice is much greater than the corresponding ratio near winter. These results reinforce the importance of ion composition in outflow models. If observed
perturbations result from Doppler‐shifted wave structures with near‐zero frequencies, we show that spacecraft frame frequencies
0.1–0.5 Hz correspond to perpendicular spatial scales of several to tens of kilometers.
Tide‐Storm Surge Interactions in Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability
Authors: Familkhalili R. , Talke S. A. , Jay D. A.
Published: March 2020

We develop idealized analytical and numerical models to study how storm surge amplitudes vary within frictional, weakly convergent, nonreflective estuaries. Friction is treated using Chebyshev polynomials. Storm surge is represented as the sum of two sinusoidal components, and a third constituent represents the semidiurnal tide (D2). An empirical fit of storm surge shows that two sinusoidal components adequately represent storm surge above a baseline value (R2 = 0.97). We find that the spatial transformation of surge amplitudes depends on the depth of the estuary, and characteristics of the surge wave including time scale, amplitude, asymmetry, and surge‐tide relative phase. Analytical model results indicate that surge amplitude decays more slowly (larger e‐folding) in a deeper channel for all surge time scales (12–72 hr). Deepening of an estuary results in larger surge amplitudes. Sensitivity studies show that surges with larger primary amplitudes (or shorter time scales) damp faster than those with smaller amplitudes (or larger time scales). Moreover, results imply that there is a location with maximum sensitivity to altered depth, offshore surge amplitude, and time scale and that the location of observed maximum change in surge amplitude along an estuary of simple form moves upstream when depth is increased. Further, the relative phase of surge to tide and surge asymmetry can change the spatial location of maximum change in surge. The largest change due to increased depth occurs for a large surge with a short time scale. The results suggest that both sea level rise and channel deepening may also alter surge amplitudes.
Topographical Control of the Source‐Sink and Wind Stress‐Driven Planetary Geostrophic Circulation in a Polar Basin
Authors: Gavilan Pascual‐Ahuir Estanislao , Willmott Andrew J. , Morales Maqueda Miguel , Luneva Maria
Published: March 2020

The effects of topography on the barotropic circulation in a polar basin are examined analytically and numerically. New approximate linear analytical solutions are presented for steady‐state wind and boundary forced barotropic planetary geostrophic circulation in a circular polar basin with a step shelf. The solutions are obtained by retaining the full spherical geometry in the derivation of the forced potential vorticity equation; thereafter the colatitude is fixed in the coefficients of this governing equation. The accuracy of the analytical solutions is evaluated by comparing them with the equivalent numerical solutions obtained using the NEMO modeling system. Subsequently, the impact of a nonuniform width shelf on source‐sink‐driven circulation is investigated numerically. The equipartition of fluid entering the source strait into cyclonic and anticyclonic shelf currents, exiting the basin at the sink strait, in a basin with a uniform width shelf is shown to be modified when the shelf width varies. In general, the wider shelf supports a current with larger transport, irrespective of the azimuthal extent of the wider shelf. The study concludes with a numerical investigation of wind‐driven circulation in a basin with a step shelf, three straits, and a transpolar ridge, a prototype Arctic Ocean simulation. Topographic steering by the ridge supports a transpolar drift current, the magnitude of which depends on the ridge height. Without the ridge, the transpolar drift current is absent and the circulation is confined to gyres on the shelf and in the deep basin.
Large Eddy Simulation on Horizontal Convective Rolls that Caused an Aircraft Accident during its Landing at Narita Airport
Authors: Ito J. , Niino H. , Yoshino K.
Published: March 2020

An accident occurred when an aircraft landed at Narita International Airport, Japan, on 20 June 2012. The aircraft encountered rapid changes of winds together with strong turbulence, although the weather was fair. In the present study, a two‐domain nested regional weather prediction models are used. The results in the outer domain show that southwesterly winds associated with a synoptic extratropical cyclone were locally accelerated to the southwest of the airport resulting in strong vertical shear. The simulation in the inner domain reproduces horizontal convective rolls, which are similar to those observed by a Doppler lidar at the airport. The wind velocity component parallel to the runway had a spatial variation of about 10 m s
. The present approach using a large eddy simulation is useful for clarifying environments and features of horizontal convective rolls and forecasting low‐level wind shear associated with them, which can be a significant risk for aircraft.
Cooperative synaptic and intrinsic plasticity in a disynaptic limbic circuit drive stress-induced anhedonia and passive coping in mice
Authors: Pignatelli Marco , Tejeda Hugo A. , Barker David J. , Bontempi Leonardo , Wu Jocelyn , Lopez Alejandra , Palma Ribeiro Sissi , Lucantonio Federica , Parise Eric M. , Torres-Berrio Angélica , Alvarez-Bagnarol Yocasta , Marino Rosa A. M. , Cai Zhao-Lin , Xue Mingshan , Morales Marisela , Tamminga Carol A. , Nestler Eric J. , Bonci Antonello
Published: March 2020

Stress promotes negative affective states, which include anhedonia and passive coping. While these features are in part mediated by neuroadaptations in brain reward circuitry, a comprehensive framework of how stress-induced negative affect may be encoded within key nodes of this circuit is lacking. Here, we show in a mouse model for stress-induced anhedonia and passive coping that these phenomena are associated with increased synaptic strength of ventral hippocampus (VH) excitatory synapses onto D1 medium spiny neurons (D1-MSNs) in the nucleus accumbens medial shell (NAcmSh), and with lateral hypothalamus (LH)-projecting D1-MSN hyperexcitability mediated by decreased inwardly rectifying potassium channel (IRK) function. Stress-induced negative affective states are prevented by depotentiation of VH to NAcmSh synapses, restoring Kir2.1 function in D1R-MSNs, or disrupting co-participation of these synaptic and intrinsic adaptations in D1-MSNs. In conclusion, our data provide strong evidence for a disynaptic pathway controlling maladaptive emotional behavior.
Moth-eye shaped on-demand broadband and switchable perfect absorbers based on vanadium dioxide
Authors: Badloe Trevon , Kim Inki , Rho Junsuk
Published: March 2020

Two biomimetic, moth-eye structure, perfect absorbers in the visible and near infrared regions are introduced and investigated. The moth-eye structure is made up of vanadium oxide (VO2), which is a phase change material that changes from an insulator state to a metallic state at around 85 °C. The VO2 structure sits on top of a sapphire (Al2O3) dielectric spacer layer, above a gold (Au) back reflector. Two perfect absorbers are designed, one with perfect absorption over an ultra-broadband range between 400 and 1,600 nm, for both the insulating and metallic phases, while the second can switch between being a perfect absorber or not in the range 1,000 and 1,600 nm. The absorption profiles and electric and magnetic fields are examined and discussed to provide insight into how absorbers function in the four different situations.
Publisher Correction: Exposure to Oil and Hypoxia Results in Alterations of Immune Transcriptional Patterns in Developing Sheepshead Minnows (Cyprinodon variegatus)
Authors: Rodgers Maria L. , Simning Danielle , Sepúlveda Maria S. , De Guise Sylvain , Bosker Thijs , Griffitt Robert J.
Published: March 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Evaluation of antifungal effect and toxicity of xanthyletin and two bacterial metabolites against Thai isolates of Pythium insidiosum
Authors: Wittayapipath Kittiya , Yenjai Chavi , Prariyachatigul Chularut , Hamal Petr
Published: March 2020

Pythiosis is a harmful disease caused by Pythium insidiosum, an aquatic oomycete. Therapeutic protocols based on antifungal drugs are often ineffective because the cytoplasmic membrane of P. insidiosum does not contain ergosterol. Therefore, the treatment of pythiosis is still challenging, particularly making use of natural products and secondary metabolites from bacteria. In this study, xanthyletin and substances obtained from Pseudomonas stutzeri ST1302 and Klebsiella pneumoniae ST2501 exhibited anti-P. insidiosum activity and, moreover, xanthyletin was non-toxic against human cell lines. The hyphae of P. insidiosum treated with these three substances exhibited lysis holes on a rough surface and release of anamorphic material. Therefore, xanthyletin could be considered a promising alternative agent for treating cutaneous pythiosis in the near future.
Quantum State Optimization and Computational Pathway Evaluation for Gate-Model Quantum Computers
Authors: Gyongyosi Laszlo
Published: March 2020

A computational problem fed into a gate-model quantum computer identifies an objective function with a particular computational pathway (objective function connectivity). The solution of the computational problem involves identifying a target objective function value that is the subject to be reached. A bottleneck in a gate-model quantum computer is the requirement of several rounds of quantum state preparations, high-cost run sequences, and multiple rounds of measurements to determine a target (optimal) state of the quantum computer that achieves the target objective function value. Here, we define a method for optimal quantum state determination and computational path evaluation for gate-model quantum computers. We prove a state determination method that finds a target system state for a quantum computer at a given target objective function value. The computational pathway evaluation procedure sets the connectivity of the objective function in the target system state on a fixed hardware architecture of the quantum computer. The proposed solution evolves the target system state without requiring the preparation of intermediate states between the initial and target states of the quantum computer. Our method avoids high-cost system state preparations and expensive running procedures and measurement apparatuses in gate-model quantum computers. The results are convenient for gate-model quantum computations and the near-term quantum devices of the quantum Internet.
Shelf humic substances as carriers for basin-scale iron transport in the North Pacific
Authors: Yamashita Youhei , Nishioka Jun , Obata Hajime , Ogawa Hiroshi
Published: March 2020

Iron is one of the key elements controlling phytoplankton growth in large areas of the global ocean. Aeolian dust has traditionally been considered the major external source of iron in the North Pacific. Recent studies have indicated that sedimentary iron from the shelf region of the Sea of Okhotsk has a strong impact on the iron distribution in the North Pacific, while the mechanism supporting its long-distance transport remains poorly understood. Here, we report that refractory shelf humic substances, which complex and carry dissolved iron, are transported conservatively at least 4000 km from the shallow sediments of the Sea of Okhotsk to the subtropical North Pacific with the circulation of intermediate water. This result indicates that shelf humic substances are probably one of the key factors shaping the distribution of dissolved iron in the ocean interior.
T-Cell Receptor Variable β Domains Rigidify During Affinity Maturation
Authors: Fernández-Quintero Monica L. , Seidler Clarissa A. , Liedl Klaus R.
Published: March 2020

We investigated T-cell receptor variable β chains binding to the superantigen staphylococcal enterotoxin C3 (SEC 3) with structure information in different stages of affinity maturation. Metadynamics in combination with molecular dynamics simulations allow to access the micro-to-millisecond timescale and reveal a strong effect of energetically significant mutations on the flexibility of the antigen-binding site. The observed changes in dynamics of the complementarity determining region (CDR) loops, especially the CDR 2, and HV 4 loop on this specific pathway of affinity maturation are reflected in their structural diversity, thermodynamics of conformations and kinetics of structural transitions. In addition, this affinity maturation pathway follows the concept of conformational selection, because even without the presence of the antigen the binding competent state is present in this pre-existing ensemble of conformations. In all stages of this affinity maturation process we observe a link between specificity and reduced flexibility.
A strategy to construct fluorescent non-aromatic small-molecules: hydrogen bonds contributing to the unexpected fluorescence
Authors: Guan Ruifang , Dong Baoli , Xu Cui , Zhang Hao , Cao Duxia , Lin Weiying
Published: March 2020

Propanedioyl dihydrazide (PDH), traditionally believed to be non-fluorescent, was first discovered to emit substantial fluorescence in both the solid state and solvents.
Development of preconcentration strategies for the simultaneous ultratrace determination of As, Cd and Pb in foods by ICP-OES: knotted-reactor vs. dispersive liquid–liquid microextraction
Authors: Martínez-Rubio David , Grindlay Guillermo , Llaver Mauricio , Wuilloud Rodolfo G. , Mora Juan
Published: March 2020

Determination of As, Cd and Pb in food samples by means of inductively coupled plasma optical emission spectrometry is challenging due to detection limits being close to the maximum levels established by current international food security policies.
Improving the throughput of immunoaffinity purification and enzymatic digestion of therapeutic proteins using membrane-immobilized reagent technology
Authors: Robinson Michelle R. , Vasicek Lisa A. , Hoppmann Christian , Li Mandy , Jokhadze Gia , Spellman Daniel S.
Published: March 2020

Rapid spin membrane technology decreases the time for IP and digestion of therapeutic proteins.