bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiology and risk factors for recurrent Staphylococcus aureus colonization following active surveillance and decolonization in the NICU
Authors: Akinboyo Ibukunoluwa C. , Voskertchian Annie , Gorfu Gezahegn , Betz Joshua F. , Ross Tracy L. , Carroll Karen C. , Milstone Aaron M.
Published: September 2018

Objectives

To examine neonatal risk factors associated with recurrent Staphylococcus aureus colonization and to determine the genetic relatedness of S. aureus strains cultured from neonates before and after decolonization.

Study design

Single-center retrospective cohort study of neonates admitted to the neonatal intensive care unit (NICU) from April 2013 to December 2015, during which weekly nasal cultures from hospitalized NICU patients were routinely obtained for S. aureus surveillance.

Setting

Johns Hopkins Hospital’s 45-bed level IV NICU in Baltimore, Maryland.

Methods

Demographics and clinical data were collected on all neonates admitted to the NICU with S. aureus nasal colonization who underwent mupirocin-based decolonization during the study period. A decolonized neonate was defined as a neonate with ≥1 negative culture after intranasal mupirocin treatment. Pulsed-field gel electrophoresis was used for strain typing.

Results

Of 2,060 infants screened for S. aureus, 271 (13%) were colonized, and 203 of these 271 (75%) received intranasal mupirocin. Of those treated, 162 (80%) had follow-up surveillance cultures, and 63 of these 162 infants (39%) developed recurrent colonization after treatment. The S. aureus strains were often genetically similar before and after decolonization. The presence of an endotracheal tube or nasal cannula/mask was associated with an increased risk of recurrent S. aureus colonization (hazard ratio [HR], 2.65; 95% confidence interval [CI], 1.19–5.90; and HR, 2.21; 95% CI, 1.02–4.75, respectively).

Conclusion

Strains identified before and after decolonization were often genetically similar, and the presence of invasive respiratory devices increased the risk of recurrent S. aureus nasal colonization in neonates. To improve decolonization efficacy, alternative strategies may be needed.
Antibiotic prescribing for acute respiratory infections in New York City: A model for collaboration
Authors: Guzik Joan , Patel Gopi , Kothari Pooja , Sharp Misha , Ostrowsky Belinda ,   the UHF Outpatient ASP Collaborative Team
Published: September 2018

Objective

To assess the status of antibiotic prescribing in the ambulatory setting for adult patients with acute respiratory infections (ARIs) and to identify opportunities and barriers for outpatient antibiotic stewardship programs (ASPs).

Design

Mixed methods including point prevalence using chart reviews, surveys, and collaborative learning.

Setting

Hospital-owned clinics in the New York City area.

Participants/Patients

In total, 31 hospital-owned clinics from 9 hospitals and health systems participated in the study to assess ARI prescribing practices for patients >18 years old.

Interventions

Each clinic performed a survey of current stewardship practices, retrospective chart reviews of prescribing in 30 randomly selected ARI patients from October 2015 to March 2016, and surveys of provider characteristics and knowledge. Clinics participated in collaborative learning with peers and experts in antibiotic stewardship and collected data from June 2016 to August 2016. Sites received data reports by individual clinic, aggregated by hospital, and were compared among participating clinics.

Results

Few sites had outpatient stewardship activities. The retrospective review of 1,004 ARI patients revealed that 37.3% of ARI patients received antibiotics, with significant variation in prescribing practices among sites (17.4%–71.0%; P<.001). Macrolides were the most commonly prescribed antibiotics. Most of the 302 respondents recognized the need for tools to assist in prescribing.

Conclusions

This collaborative study establishes a baseline assessment of the status of outpatient ASPs in New York City. It provides hospitals, health systems, and individual clinics with specific data to inform their development of stewardship interventions targeting ARIs.
Breaking of modulated wave groups: kinematics and energy dissipation processes
Authors: De Vita Francesco , Verzicco Roberto , Iafrati Alessandro
Published: September 2018

The two-dimensional flow induced by the breaking of modulated wave trains is numerically investigated using the open source software Gerris (Popinet, J. Comput. Phys., vol. 190, 2003, pp. 572–600; J. Comput. Phys., vol. 228, 2009, pp. 5838–5866. The two-phase flow is modelled by the Navier–Stokes equations for a single fluid with variable density and viscosity, coupled with a volume-of-fluid (VOF) technique for the capturing of the interface dynamics. The breaking is induced through the Benjamin–Feir mechanism, by adding two sideband disturbances to a fundamental wave component. The evolution of the wave system is simulated starting from the initial condition until the end of the breaking process, and the role played by the initial wave steepness is investigated. As already noted in previous studies as well as in field observations, it is found that the breaking is recurrent and several breaking events are needed before the breaking process finally ceases. The down-shifting of the fundamental component to the lower sideband is made irreversible by the breaking. At the end of the breaking process the magnitude of the lower sideband component is approximately 80 % of the initial value of the fundamental one. The time histories of the energy content in water and the energy dissipation are analysed. The whole breaking process dissipates a fraction of between twenty and twenty-five per cent of the pre-breaking energy content, independently of the initial steepness. The energy contents of the different waves of the group are evaluated and it is found that after the breaking, the energy of the most energetic wave of the group decays as

$t^{-1}$

.
Control of flow around a cylinder by rotary oscillations at a high subcritical Reynolds number
Authors: Palkin E. , Hadžiabdić M. , Mullyadzhanov R. , Hanjalić K.
Published: September 2018

We report on a numerical study of the vortex structure modifications and drag reduction in a flow over a rotationally oscillating circular cylinder at a high subcritical Reynolds number,

$Re=1.4\times 10^{5}$

. Considered are eight forcing frequencies

$f=f_{e}/f_{0}=0.5$

,

$1$

,

$1.5$

,

$2$

,

$2.5$

,

$3$

,

$4$

,

$5$

and three forcing amplitudes

$\unicode[STIX]{x1D6FA}=\unicode[STIX]{x1D6FA}_{e}D/2U_{\infty }=1$

,

$2$

,

$3$

, non-dimensionalized with

$f_{0}$

, which is the natural vortex-shedding frequency without forcing,

$U_{\infty }$

the free-stream velocity,

$D$

the diameter of the cylinder. In order to perform a parametric study of a large number of cases (

$24$

in total) with affordable computational resources, the three-dimensional unsteady computations were performed using a wall-integrated (WIN) second-moment (Reynolds-stress) Reynolds-averaged Navier–Stokes (RANS) turbulence closure, verified and validated by a dynamic large-eddy simulations (LES) for selected cases (

$f=2.5$

,

$\unicode[STIX]{x1D6FA}=2$

and

$f=4$

,

$\unicode[STIX]{x1D6FA}=2$

), as well as by the earlier LES and experiments of the flow over a stagnant cylinder at the same

$Re$

number described in Palkin et al. (Flow Turbul. Combust., vol. 97 (4), 2016, pp. 1017–1046). The drag reduction was detected at frequencies equal to and larger than

$f=2.5$

, while no reduction was observed for the cylinder subjected to oscillations with the natural frequency, even with very different values of the rotation amplitude. The maximum reduction of the drag coefficient is 88 % for the highest tested frequency

$f=5$

and amplitude

$\unicode[STIX]{x1D6FA}=2$

. However, a significant reduction of 78 % appears with the increase of

$f$

already for

$f=2.5$

and

$\unicode[STIX]{x1D6FA}=2$

. Such a dramatic reduction in the drag coefficient is the consequence of restructuring of the vortex-shedding topology and a markedly different pressure field featured by a shrinking of the low pressure region behind the cylinder, all dictated by the rotary oscillation. Despite the need to expend energy to force cylinder oscillations, the considered drag reduction mechanism seems a feasible practical option for drag control in some applications for

$Re>10^{4}$

, since the calculated power expenditure for cylinder oscillation under realistic scenarios is several times smaller than the power saved by the drag reduction.
Vortex sheet roll-up revisited
Authors: DeVoria A. C. , Mohseni K.
Published: September 2018

The classical problem of roll-up of a two-dimensional free inviscid vortex sheet is reconsidered. The singular governing equation brings with it considerable difficulty in terms of actual calculation of the sheet dynamics. Here, the sheet is discretized into segments that maintain it as a continuous object with curvature. A model for the self-induced velocity of a finite segment is derived based on the physical consideration that the velocity remain bounded. This allows direct integration through the singularity of the Birkhoff–Rott equation. The self-induced velocity of the segments represents the explicit inclusion of stretching of the sheet and thus vorticity transport. The method is applied to two benchmark cases. The first is a finite vortex sheet with an elliptical circulation distribution. It is found that the self-induced velocity is most relevant in regions where the curvature and the sheet strength or its gradient are large. The second is the Kelvin–Helmholtz instability of an infinite vortex sheet. The critical time at which the sheet forms a singularity in curvature is accurately predicted. As observed by others, the vortex sheet strength forms a finite-valued cusp at this time. Here, it is shown that the cusp value rapidly increases after the critical time and is the impetus that initiates the roll-up process.
How the Tivaevae Model can be Used as an Indigenous Methodology in Cook Islands Education Settings
Authors: Te Ava Aue , Page Angela
Published: September 2018

This paper explores an Indigenous research methodology, the tivaevae model, and its application within the Cook Islands education system. The article will argue that the cultural values embedded within its framework allow for the successful implementation of this Indigenous methodology. The model draws from tivaevae, or artistic quilting, and is both an applique process and a product of the Cook Islands. It is unique to the Cook Islands and plays an important part in the lives of Cook Islanders. The tivaevae model will be explained in detail, describing how patchwork creative pieces come together to create a story and can be used as a metaphor of the past, present and future integration of social, historical, spiritual, religious, economic and political representations of Cook Island culture. Further, the paper will then make links with the model to teaching and learning, by exploring secondary schools’ health and physical education policy and practices. Finally, the efficacy of the model in this context and its research implications will then be discussed.
The impact of abusive supervision on employees’ feedback avoidance and subsequent help-seeking behaviour: A moderated mediation model
Authors: Arain Ghulam Ali , Bukhari Sehrish , Khan Abdul Karim , Hameed Imran
Published: September 2018

Based on the conservation of resource theory, this study investigated a moderated mediation model in which perceived co-worker support moderated the mediation of supervisory feedback avoidance between abusive supervision and help-seeking behaviour. Data from matching dyads of 220 house officers and 86 postgraduate medical staff were collected from several hospitals in Pakistan. Results of hierarchical multiple regression analyses supported the hypothesized model that abusive supervision first positively led to supervisory feedback avoidance, which in turn positively led to help-seeking from co-workers. Moreover, the mediating effect of supervisory feedback avoidance was stronger at the high value of co-worker support than that at the low value of co-worker support. This study contributes to the recently emerged notion in abusive supervision research that supervisees’ perception of abusive supervision may not always lead to abundantly reported negative work behaviours; instead, it may also lead to positive work behaviours, such as help-seeking behaviour that is highly beneficial for both supervisees and the organization.
Carcharodontosaurian remains (Dinosauria, Theropoda) from the Upper Jurassic of Portugal
Authors: Malafaia Elisabete , Mocho Pedro , Escaso Fernando , Dantas Pedro , Ortega Francisco
Published: September 2018

A new specimen of a theropod dinosaur found in the Upper Jurassic (Freixial Formation, late Tithonian) of the Lusitanian Basin is described. It corresponds to a single individual and includes a sequence of articulated caudal vertebrae, an almost complete right pes, and other fragments of the appendicular skeleton. The specimen includes the most complete pes of a theropod dinosaur currently known in the Lusitanian Basin and represents one of the youngest skeletal records of theropod dinosaurs currently known in the Portuguese Upper Jurassic.

A systematic analysis of this specimen is performed and it shows a combination of characters that allows us to interpret it as belonging to an allosauroid taxon. Within this clade, the material from Cambelas shares a few features with some carcharodontosaurids, including the presence of a lateral lamina extending along the anterior end of the centrum in the caudal vertebra and of a low vertical crest on the lateral surface of the femoral lesser trochanter. The set of remains described here shares some unusual features with another specimen previously described in the Portuguese fossil record, which also presents some synapomorphies of Carcharodontosauria. However, no autapomorphy or exclusive character combination can be recognized in the specimen here described in order to describe it as a new form. The presence of this specimen suggests a greater diversity in the allosauroid theropod fauna from the Late Jurassic of the Lusitanian Basin than currently known and probably expands the temporal record of Carcharodontosauria up to upper Tithonian of south-western Europe.
Environmental influence on growth history in marine benthic foraminifera
Authors: Keating-Bitonti Caitlin R. , Payne Jonathan L.
Published: September 2018

Energy availability influences natural selection on the ontogenetic histories of organisms. However, it remains unclear whether physiological controls on size remain constant throughout ontogeny or instead shift as organisms grow larger. Benthic foraminifera provide an opportunity to quantify and interpret the physicochemical controls on both initial (proloculus) and adult volumes across broad environmental gradients using first principles of cell physiology. Here, we measured proloculus and adult test dimensions of 129 modern rotaliid species from published images of holotype specimens, using holotype size to represent the maximum size of all species’ occurrences across the North American continental margin. We merged size data with mean annual temperature, dissolved oxygen concentration, particulate organic carbon flux, and seawater calcite saturation for 718 unique localities to quantify the relationship between physicochemical variables and among-species adult/proloculus size ratios. We find that correlation of community mean adult/proloculus size ratios with environmental parameters reflects covariation of adult test volume with environmental conditions. Among-species proloculus sizes do not covary identifiably with environmental conditions, consistent with the expectation that environmental constraints on organism size impose stronger selective pressures on adult forms due to lower surface area-to-volume ratios at larger sizes. Among-species adult/proloculus size ratios of foraminifera occurring in resource-limited environments are constrained by the limiting resource in addition to temperature. Identified limiting resources are food in oligotrophic waters and oxygen in oxygen minimum zones. Because among-species variations in adult/proloculus size ratios from the North American continental margin are primarily driven by the local environment’s influence on adult sizes, the evolution of foraminiferal sizes over the Phanerozoic may have been strongly influenced by changing oceanographic conditions. Furthermore, lack of correspondence between among-species proloculus sizes and environmental conditions suggests that offspring sizes in foraminifera are rarely limited by physiological constraints and are more susceptible to selection related to other aspects of fitness.
The non-modal onset of the tearing instability
Authors: MacTaggart D.
Published: September 2018

We investigate the onset of the classical magnetohydrodynamic (MHD) tearing instability (TI) and focus on non-modal (transient) growth rather than the tearing mode. With the help of pseudospectral theory, the operators of the linear equations are shown to be highly non-normal, resulting in the possibility of significant transient growth at the onset of the TI. This possibility increases as the Lundquist number$S$increases. In particular, we find evidence, numerically, that the maximum possible transient growth, measured in the$L_{2}$-norm, for the classical set-up of current sheets unstable to the TI, scales as$O(S^{1/4})$on time scales of$O(S^{1/4})$for$S\gg 1$. This behaviour is much faster than the time scale$O(S^{1/2})$when the solution behaviour is dominated by the tearing mode. The size of transient growth obtained is dependent on the form of the initial perturbation. Optimal initial conditions for the maximum possible transient growth are determined, which take the form of wave packets and can be thought of as noise concentrated at the current sheet. We also examine how the structure of the eigenvalue spectrum relates to physical quantities.
Comparison of cognitive functions between first-episode schizophrenia patients, their unaffected siblings and individuals at clinical high-risk for psychosis
Authors: Chu Angel On Ki , Chang Wing Chung , Chan Sherry Kit Wa , Lee Edwin Ho Ming , Hui Christy Lai Ming , Chen Eric Yu Hai
Published: September 2018

Background

Cognitive impairment is a core feature of schizophrenia and has been observed in both familial (FHR) and clinical high-risk (CHR) samples. Nonetheless, there is a paucity of research directly contrasting cognitive profiles in these two high-risk states and first-episode schizophrenia. This study aimed to compare cognitive functions in patients with first-episode schizophrenia-spectrum disorder (FES), their unaffected siblings (FHR), CHR individuals and healthy controls.

Method

A standardized battery of cognitive assessments was administered to 69 FES patients, 71 help-seeking CHR individuals without family history of psychotic disorder, 50 FHR participants and 68 controls. FES and CHR participants were recruited from territory-wide early intervention service for psychosis in Hong Kong. CHR status was ascertained using Comprehensive Assessment of At-Risk Mental State.

Results

Among four groups, FES patients displayed the largest global cognitive impairment and had medium-to-large deficits across all cognitive tests relative to controls. CHR and FHR participants significantly underperformed in most cognitive tests than controls. Among various cognitive tests, digit symbol coding demonstrated the greatest magnitude of impairment in FES and CHR groups compared with controls. No significant difference between two high-risk groups was observed in global cognition and all individual cognitive tests except digit symbol coding which showed greater deficits in CHR than in FHR participants.

Conclusion

Clinical and familial risk groups experienced largely comparable cognitive impairment that was intermediate between FES and controls. Digit symbol coding may have the greatest discriminant capacity in distinguishing FES and CHR from healthy controls, and between two high-risk samples.
Generation of uniform transverse beam distributions for high-energy electron radiography
Authors: Zhao Q.T. , Cao S.C. , Cheng R. , Du Y.C. , Shen X.K. , Wang Y.R. , Xiao J.H. , Zong Y. , Zhu Y.L. , Zhou Y.W. , Zhao Y.T. , Zhang Z.M. , Gai W.
Published: September 2018

High-energy electron radiography (HEER) has been proposed for time-resolved imaging of materials, high-energy density matter, and for inertial confinement fusion. The areal-density resolution, determined by the image intensity information is critical for these types of diagnostics. Preliminary experimental studies for different materials with the same thickness and the same areal-density target have been imaged and analyzed. Although there are some discrepancies between experimental and theory analysis, the results show that the density distribution can indeed be attained from HEER. The reason for the discrepancies has been investigated and indicates the importance of the uniformity in the transverse distribution beam illuminating the target. Furthermore, the method for generating a uniform transverse distribution beam using octupole magnets was studied and verified by simulations. The simulations also confirm that the octupole field does not affect the angle-position correlation in the center part beam, a critical requirement for the imaging lens. A more practical method for HEER using collimators and octupoles for generating more uniform beams is also described. Detailed experimental results and simulation studies are presented in this paper.
TESTING REGRESSION MONOTONICITY IN ECONOMETRIC MODELS
Authors: Chetverikov Denis
Published: September 2018

Monotonicity is a key qualitative prediction of a wide array of economic models derived via robust comparative statics. It is therefore important to design effective and practical econometric methods for testing this prediction in empirical analysis. This article develops a general nonparametric framework for testing monotonicity of a regression function. Using this framework, a broad class of new tests is introduced, which gives an empirical researcher a lot of flexibility to incorporate ex ante information she might have. The article also develops new methods for simulating critical values, which are based on the combination of a bootstrap procedure and new selection algorithms. These methods yield tests that have correct asymptotic size and are asymptotically nonconservative. It is also shown how to obtain an adaptive and rate optimal test that has the best attainable rate of uniform consistency against models whose regression function has Lipschitz-continuous first-order derivatives and that automatically adapts to the unknown smoothness of the regression function. Simulations show that the power of the new tests in many cases significantly exceeds that of some prior tests, e.g., that of Ghosal, Sen, and Van der Vaart (2000).
‘She had it coming?’: An experimental study of text interpretation in a police classroom setting
Authors: Ask Sofia
Published: September 2018

The aim of this study is to investigate how modifications of reporting verbs, modality, style and use of quotation marks in an authentic police report can lead to different interpretations by two groups of trainee police officers. Data was collected through an experiment in a classroom setting, where police trainees discussed two versions of the same police report in focus group discussions. The trainees’ statements were categorised into three themes: impression of the victim, impression of the accused, and assessment of the situation's severity. The results show that modifications such as formal or informal choice of words and the use of scare quotes proved to be influential linguistic modifications. In contrast, variation of reporting verbs and modality appeared less significant. The two versions of the text created different impressions of both the victim and the accused, and the interpretations of the severity of the situation depicted in the text varied between the two trainee groups. This highlights the importance of further study of the linguistic constructions of victims and perpetrators in police texts, in order to ensure credibility and equality before the law.
Introduction to special issue on Forensic Linguistics: European Perspectives
Authors: Christensen Tanya Karoli , Mortensen Sune Sønderberg
Published: September 2018

This special issue ofNordic Journal of Linguisticsis dedicated to the emerging field of forensic linguistics. There are competing definitions and delimitations of this term but here we will use it to refer to the investigation and elucidation of language evidence in a legal context. This includes the scrutiny of language data from different stages of the legal process, ranging from emergency calls to police interviews and courtroom interaction, as well as expert assessment and witness testimony in cases where the meaning or authorship of texts or utterances are questioned. While the analysis of authentic case data is often preferred or even required, access to such highly sensitive data types is naturally restricted by legal and ethical boundaries. An increasing amount of studies therefore employ experimental designs to test hypotheses and improve methodologies.
Urbanization Around an Airfield Alters Bird Community Composition, but not the Hazard of Bird–Aircraft Collision
Authors: Jeffery Roderick F. , Buschke Falko T.
Published: September 2018

Bird strikes are a considerable hazard to the aviation industry, which has led airports to develop detailed management strategies to identify and reduce the risk of them. These strategies include plans to modify bird habitats in and around airports to limit the establishment of high-risk species. Although airports are generally located on the outskirts of towns and cities, they may be encroached on by urban sprawl. In this study, we examined how an urbanization gradient affects the bird community around an air force base in Cape Town (South Africa) and quantified how this could modify the hazard of bird–aircraft collision. We surveyed the bird community in and around the Air Force Base Ysterplaat across four seasons and categorized species based on their response to increased urbanization (urban avoiders, adapters and exploiters). By combining this with species-specific information on body size, flock size, flight behaviour and abundance, we showed that although urbanization affects bird composition, the overall hazard of bird–aircraft collision is consistent regardless of urban response. However, urbanization complicates mitigation in the matrix surrounding the airport and creates novel challenges for the management of bird hazards. Therefore, new bird hazard management strategies should be integrated within community-driven land-use planning to minimize the negative effects of bird–aircraft collisions.
Scaling laws and warning signs for bifurcations of SPDEs
Authors: KUEHN CHRISTIAN , ROMANO FRANCESCO
Published: September 2018

Critical transitions (or tipping points) are drastic sudden changes observed in many dynamical systems. Large classes of critical transitions are associated with systems, which drift slowly towards a bifurcation point. In the context of stochastic ordinary differential equations, there are results on growth of variance and autocorrelation before a transition, which can be used as possible warning signs in applications. A similar theory has recently been developed in the simplest setting for stochastic partial differential equations (SPDEs) for self-adjoint operators in the drift term. This setting leads to real discrete spectrum and growth of the covariance operator via a certain scaling law. In this paper, we develop this theory substantially further. We cover the cases of complex eigenvalues, degenerate eigenvalues as well as continuous spectrum. This provides a fairly comprehensive theory for most practical applications of warning signs for SPDE bifurcations.
Asymptotic solutions of the Helmholtz equation: Generalised Friedlander–Keller ray expansions of fractional order
Authors: TEW R. H.
Published: September 2018

Applications of a WKBJ-type ‘ray ansatz’ to obtain asymptotic solutions of the Helmholtz equation in the high-frequency limit are now standard and underpin the construction of ‘geometrical optics’ ray diagrams in many electromagnetic, acoustic and elastic reflection, transmission and other scattering problems. These applications were subsequently extended by Keller to include other types of rays – called ‘diffracted’ rays – to provide an accessible and impressively accurate theory which is relevant in wide-ranging sets of circumstances. Friedlander and Keller then introduced a modified ray ansatz to extend yet further the scope of ray theory and its applicability to certain other classes of diffraction problems (tangential ray incidence upon an obstructing boundary, for instance) and did so by the inclusion of an extra term proportional to a power of the wave number within the exponent of the initial ansatz. Our purpose here is to generalise this further still by the inclusion of several such terms, ordered in a natural sequence in terms of strategically chosen fractional powers of the large wave number, and to derive a systematic sequence of boundary value problems for the coefficient phase functions that arise within this generalised exponent, as well as one for the leading-order amplitude occurring as a pre-exponential factor. One particular choice of fractional power is considered in detail, and waves with specified radially symmetric or planar wavefronts are then analysed, along with a boundary value problem typifying two-dimensional radiation whereby arbitrary phase and amplitude variations are specified on a prescribed boundary curve. This theory is then applied to the scattering of plane and cylindrical waves at curved boundaries with small-scale perturbations to their underlying profile.
Asymptotic and transient behaviour for a nonlocal problem arising in population genetics
Authors: BURIE J.-B. , DJIDJOU-DEMASSE R. , DUCROT A.
Published: September 2018

This work is devoted to the study of an integro-differential system of equations modelling the genetic adaptation of a pathogen by taking into account both mutation and selection processes. First, we study the asymptotic behaviour of the system and prove that it eventually converges to a stationary state. Next, we more closely investigate the behaviour of the system in the presence of multiple EAs. Under suitable assumptions and based on a small mutation variance asymptotic, we describe the existence of a long transient regime during which the pathogen population remains far from its asymptotic behaviour and highly concentrated around some phenotypic value that is different from the one described by its asymptotic behaviour. In that setting, the time needed for the system to reach its large time configuration is very long and multiple evolutionary attractors may act as a barrier of evolution that can be very long to bypass.
Theoretical and experimental study of a pendulum excited by random loads
Authors: DOSTAL L. , PICK M.-A.
Published: September 2018

Results on the behaviour of a pendulum which is parametrically excited by large amplitude random loads at its pivot are presented, including a novel experimental case study. Thereby, it is dealt with a random excitation by a non-white Gaussian stochastic process with prescribed spectral density. Special focus is devoted to stochastic processes resulting from random sea wave elevation and the question whether random sea waves can lead to rotational motion of the parametrically excited pendulum. The motivation for such an experimental study is energy harvesting from ocean waves.
Variation in total root length and root diameter of wild and cultivated lentil grown under drought and re-watered conditions
Authors: Gorim Linda Yuya , Vandenberg Albert
Published: September 2018

Lentil is now an integral part of prairie cropping systems. Climate forecasts point to variable and increased drought frequency, putting lentil production in jeopardy. Future lentil genotypes will require root systems that can extract more water under drought conditions. This study focuses on root diameter and root tip number, traits known to play an important role in water uptake during drought. We compared the total root length (TRL) in three soil horizons of both wild and cultivated lentil genotypes for three root diameter classes when plants were grown under moderate or severe drought, and when re-watered after exposure to moderate drought conditions. Our study demonstrates that roots of both wild and cultivated lentil genotypes can be categorized into very fine, fine and small diameter classes. Some wild lentil genotypes had significantly higher TRL in the B and C soil horizons when grown under severe or moderate drought and therefore, could act as resources for the transfer of root traits to cultivated lentil genotypes. Further evaluations focused on the root systems of interspecific recombinant inbred lines under drought conditions will be required to determine whether these traits are heritable.
The association between gestational age and otitis media during childhood: a population-based cohort analysis
Authors: Imterat Majdi , Wainstock Tamar , Moran-Gilad Jacob , Sheiner Eyal , Walfisch Asnat
Published: September 2018

Otitis media (OM) carries a tremendous global health burden and potentially severe long-term consequences. The objective of this study was to determine the impact of birth at different gestational ages on the incidence of childhood OM.

A population-based cohort analysis was conducted. All singleton deliveries occurring between 1991 and 2014 at a regional tertiary medical center were included. Gestational age on delivery was divided into six subgroups: early (<34 weeks gestation; 0 out of 7) and late (34 weeks gestation; 0 out of 7 to 36 weeks gestation; 6 out of 7) preterm, and early (37 weeks gestation; 0 out of 7 to 38 weeks gestation; 6 out of 7), full (39 weeks gestation; 0 out of 7 to 40 weeks gestation; 6 out of 7), late (41 weeks gestation; 0 out of 7 to 41 weeks gestation; 6 out of 7) and post (⩾42 weeks 0 out of 7) term deliveries. Rates of OM-related hospitalizations up to 18 years of age were assessed. Weibull parametric hazards model was used to study the association between gestational age at birth and the risk for OM-related hospitalizations while controlling for potential confounders.

During the study period, 238,622 deliveries met the inclusion criteria. OM-related hospitalizations of the offspring (n=4724) were significantly more common in the preterm (early 3.6%, late 2.4%) and early-term born children (2.2%) and decreased gradually across the full (1.9%), late (1.7%) and post (1.6%) term groups (χ2-test for trendsP<0.001). In the Weibull regression model, early preterm, as well as early-term deliveries exhibited an independent association with pediatric OM (adjusted hazard ratios: 1.67 and 1.09, respectively,P<0.02).

Deliveries occurring at preterm and early term are associated with higher rates of pediatric OM-related hospitalizations, which decrease gradually as gestational age advances.
Control of Nitrogen Exports From River Basins to the Coastal Ocean: Evaluation of Basin Management Strategies for Reducing Coastal Hypoxia
Authors: Lee M. , Jung C. , Shevliakova E. , Malyshev S. , Han H. , Kim S. , Kim K. , Jaffé P. R.
Published: September 2018

The spread of coastal hypoxia is a pressing global problem, largely caused by substantial nitrogen (N) exports from river basins to the coastal ocean. Most previous process‐based modeling studies for investigating basin management strategies to reduce river N exports focused on the impacts of different farming practices or land use, used watershed models that simplified many mechanisms that critically affect the state of N storage in land, were limited mainly to fairly small basins, and did not span multiple climate regimes. Here we use a process‐based land‐river model to simulate historical (1999–2010) river flows and nitrate‐N exports throughout the entire drainage network of South Korea (100,210 km2), which encompasses varying climate, land use, and hydrogeological characteristics. Based on projections by using multiple scenarios of N input reductions and climates, we explore the impacts of various ecosystem factors (i.e., N storage in basins, climate and its variability, anthropogenic N inputs, and basin location) on river nitrate‐N exports. Our findings have fundamental implications for reducing coastal hypoxia: (1) a small reduction of N inputs in basins, including intensively utilized human land use, can have a greater improvement on water quality; (2) heightening climate variability may not increase long‐term mean river N exports yet can significantly mask N input reduction effects by producing N export extremes associated with recurring coastal hypoxia; and (3) N exports to the coastal ocean can be most efficiently reduced by decreasing N inputs in subbasins, which are receiving high anthropogenic N inputs and are close to the coast.
Dominant Biological Control Over Upwelling on pCO2 in Sea East of Sri Lanka
Authors: Chakraborty Kunal , Valsala Vinu , Gupta G.V.M. , Sarma V.V.S.S.
Published: September 2018

Upwelling enhances pCO2 levels due to injection of carbon‐rich water to the surface despite the removal of carbon due to increase in primary production supported by enhanced nutrients. It is hypothesized that in the Bay of Bengal, upwelling may decrease pCO2 due to existence of low saline and pCO2‐poor waters in the subsurface layer. In order to test this hypothesis, a high‐resolution state‐of‐the‐art ocean biogeochemical model (Regional Ocean Modeling System) runs are examined at the sea east of Sri Lanka (SESL) where intense upwelling occurs during summer monsoon (May to August). Upwelling enhances pCO2 by 34 μatm, whereas decrease in surface temperature and increase in surface salinity reduce pCO2 by 24 μatm. The estimated net effect of upwelling is an increase in pCO2 by 10 μatm. In contrast, soft and hard tissues together contribute to a decrease in pCO2 by 21 μatm suggesting that the biological effect dominates over upwelling, resulting in a net decrease of pCO2 by 11 μatm in the SESL. This striking contrast between the increase in pCO2 due to physical dynamics (upwelling) and the removal of pCO2 due to biological processes is caused by shallow (deep) nitracline (dissolved inorganic carbon‐isoline) in the SESL.
Seasonal and Geographic Variation in Dissolved Carbon Biogeochemistry of Rivers Draining to the Canadian Arctic Ocean and Hudson Bay
Authors: Li Yung Lung Joanna Y. S. , Tank Suzanne E. , Spence Christopher , Yang Daqing , Bonsal Barrie , McClelland James W. , Holmes Robert M.
Published: September 2018

The chemical composition of river water can be used to diagnose change on land, while playing a determining role in the ecology and biogeochemistry of riverine‐influenced ocean waters. Despite this, little is known about the seasonal and geographic variability of riverine chemistry throughout much of the Canadian north. Here we assess the chemical composition of a broad suite of rivers draining to the Canadian Arctic Ocean and Hudson Bay using previously unpublished government data. We focus on inorganic and organic carbon (alkalinity and dissolved organic carbon), using paired chemistry and discharge measurements to assess constituent flux. Concentrations and area‐normalized yields vary substantially across the northern Canadian landscape, with dissolved organic carbon typically highest in rivers draining the Hudson Bay Lowland, alkalinity highest in rivers draining Cordillera and Plains terrains, and the ratio of organic to inorganic species highest in rivers draining the Canadian Shield. Yields of major weathering ions show that carbonate weathering—a notable proportion of which may be driven by sulfide oxidation—dominates inorganic carbon delivery from the rivers we assess. Despite the reasonably diverse coverage of the data set, we find that clear gaps exist, including a lack of data through to the present day for many rivers, and a dearth of measurements from the Arctic Archipelago and eastern shores of Hudson Bay. We therefore use a modeling approach to extrapolate fluxes to the full Canadian Arctic drainage basin. Region‐specific differences between our results and previous models reinforce the need for targeted river water chemistry measures throughout the Canadian Arctic domain.
El Niño Increases High‐Tide Flooding in Tidal Wetlands Along the U.S. Pacific Coast
Authors: Goodman Arianna C. , Thorne Karen M. , Buffington Kevin J. , Freeman Chase M. , Janousek Christopher N.
Published: September 2018

Periodic oscillations between El Niño and La Niña conditions in the Pacific Basin affect oceanographic and meteorological phenomena globally, with impacts on the abundance and distribution of marine species. However, El Niño effects on estuarine hydrology and tidal wetland processes have seldom been examined rigorously. We used detailed wetland elevation and local inundation data from 10 tidal wetlands located along the Pacific coast of the United States to assess changes in flooding during the 2015–2016 El Niño and to determine decadal‐scale relationships between estuarine sea‐level anomalies and Pacific Basin climate indices for this region. During the 2015–2016 El Niño all sites experienced significant increases in high‐tide water levels exceeding those predicted by astronomical tides, and increased flooding frequency during at least one of the El Niño subperiods relative to pre‐El Niño conditions. The magnitude of positive sea‐level anomalies varied by site (4–15 cm), with local hot spots of high water in southern Oregon, northern California, and Pt. Mugu lagoon in the Southern California Bight. Furthermore, over the last three decades of historic tide records, there were positive relationships between high‐tide sea‐level anomalies and equatorial Pacific Basin sea surface temperature anomalies across the region, and negative relationships with the Northern Oscillation Index. Increases of 1 °C in equatorial sea surface temperature were associated with 3–5 cm of increased high‐tide flooding at the sites. Elevated estuarine flooding associated with future El Niños could impact important tidal wetland processes and could be an additive stressor for wetlands facing accelerating sea‐level rise.
Single-cell genomics uncover Pelagibacter as the putative host of the extremely abundant uncultured 37-F6 viral population in the ocean
Authors: Martinez-Hernandez Francisco , Fornas Òscar , Lluesma Gomez Monica , Garcia-Heredia Inmaculada , Maestre-Carballa Lucia , López-Pérez Mario , Haro-Moreno Jose M , Rodriguez-Valera Francisco , Martinez-Garcia Manuel
Published: September 2018

The identification of relevant virus–host pairs that globally account for a large pool of carbon and nutrients in the ocean is paramount to build accurate ecological models. A previous work using single-virus genomics led to the discovery of the uncultured single-virus vSAG 37-F6, originally sorted from the Mediterranean Sea (Blanes Bay Microbial Observatory), that represents one of the most abundant dsDNA viral population in the marine surface virosphere. Here, from same sampling site, we report that a Pelagibacter single-cell contained a viral member of vSAG 37-F6 population, by means of PCR screening of sorted, genome-amplified single cells with vSAG 37-F6-specific primers and whole-genome sequencing. Furthermore, viruses from this population were also found in three other Pelagibacter single cells from the South Pacific and Atlantic oceans. These new uncultured pelagiphages were genetically different from the previously characterized pelagiphage isolates. Data showed that the uncultured vSAG 37-F6 population represents the Pelagibacter phages that inhabit the sunlit ocean better, and contains a vast unrecognized microdiversity.
OCP–FRP protein complex topologies suggest a mechanism for controlling high light tolerance in cyanobacteria
Authors: Sluchanko Nikolai N. , Slonimskiy Yury B. , Shirshin Evgeny A. , Moldenhauer Marcus , Friedrich Thomas , Maksimov Eugene G.
Published: September 2018

In cyanobacteria, high light photoactivates the orange carotenoid protein (OCP) that binds to antennae complexes, dissipating energy and preventing the destruction of the photosynthetic apparatus. At low light, OCP is efficiently deactivated by a poorly understood action of the dimeric fluorescence recovery protein (FRP). Here, we engineer FRP variants with defined oligomeric states and scrutinize their functional interaction with OCP. Complemented by disulfide trapping and chemical crosslinking, structural analysis in solution reveals the topology of metastable complexes of OCP and the FRP scaffold with different stoichiometries. Unable to tightly bind monomeric FRP, photoactivated OCP recruits dimeric FRP, which subsequently monomerizes giving 1:1 complexes. This could be facilitated by a transient OCP–2FRP–OCP complex formed via the two FRP head domains, significantly improving FRP efficiency at elevated OCP levels. By identifying key molecular interfaces, our findings may inspire the design of optically triggered systems transducing light signals into protein–protein interactions.
Gas-solid reaction based over one-micrometer thick stable perovskite films for efficient solar cells and modules
Authors: Liu Zonghao , Qiu Longbin , Juarez-Perez Emilio J. , Hawash Zafer , Kim Taehoon , Jiang Yan , Wu Zhifang , Raga Sonia R. , Ono Luis K. , Liu Shengzhong , Qi Yabing
Published: September 2018

Besides high efficiency, the stability and reproducibility of perovskite solar cells (PSCs) are also key for their commercialization. Herein, we report a simple perovskite formation method to fabricate perovskite films with thickness over 1 μm in ambient condition on the basis of the fast gas−solid reaction of chlorine-incorporated hydrogen lead triiodide and methylamine gas. The resultant thick and smooth chlorine-incorporated perovskite films exhibit full coverage, improved crystallinity, low surface roughness and low thickness variation. The resultant PSCs achieve an average power conversion efficiency of 19.1 ± 0.4% with good reproducibility. Meanwhile, this method enables an active area efficiency of 15.3% for 5 cm × 5 cm solar modules. The un-encapsulated PSCs exhibit an excellent T80 lifetime exceeding 1600 h under continuous operation conditions in dry nitrogen environment.
Direct electric field imaging of graphene defects
Authors: Ishikawa Ryo , Findlay Scott D. , Seki Takehito , Sánchez-Santolino Gabriel , Kohno Yuji , Ikuhara Yuichi , Shibata Naoya
Published: September 2018

Material properties are sensitive to atomistic structure defects such as vacancies or impurities, and it is therefore important to determine not only the local atomic configuration but also their chemical bonding state. Annular dark-field scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy has been utilized to investigate the local electronic structures of such defects down to the level of single atoms. However, it is still challenging to two-dimensionally map the local bonding states, because the electronic fine-structure signal from a single atom is extremely weak. Here, we show that atomic-resolution differential phase-contrast STEM imaging can directly visualize the anisotropy of single Si atomic electric fields in monolayer graphene. We also visualize the atomic electric fields of Stone–Wales defects and nanopores in graphene. Our results open the way to directly examine the local chemistry of the defective structures in materials at atomistic dimensions.