bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous breaking of Weyl quadratic gravity to Einstein action and Higgs potential
Authors: Ghilencea D. M.
Published: March 2019

Abstract

We consider the (gauged) Weyl gravity action, quadratic in the scalar curvature (

$$ \tilde{R} $$

R
˜

) and in the Weyl tensor (

$$ {\tilde{C}}_{\mu \nu \rho \sigma} $$

C
˜

μνρσ

) of the Weyl conformal geometry. In the absence of matter fields, this action has spontaneous breaking in which the Weyl gauge field ω

μ
becomes massive (mass m

ω
∼ Planck scale) after “eating” the dilaton in the

$$ \tilde{R} $$

R
˜

2 term, in a Stueckelberg mechanism. As a result, one recovers the Einstein-Hilbert action with a positive cosmological constant and the Proca action for the massive Weyl gauge field ω

μ
. Below m

ω
this field decouples and Weyl geometry becomes Riemannian. The Einstein-Hilbert action is then just a “low-energy” limit of Weyl quadratic gravity which thus avoids its previous, long-held criticisms. In the presence of matter scalar field ϕ
1 (Higgs-like), with couplings allowed by Weyl gauge symmetry, after its spontaneous breaking one obtains in addition, at low scales, a Higgs potential with spontaneous electroweak symmetry breaking. This is induced by the non-minimal coupling

$$ {\xi}_1{\phi}_1^2\tilde{R} $$

ξ
1

ϕ
1
2

R
˜

to Weyl geometry, with Higgs mass ∝ ξ1/ξ0 (ξ0 is the coefficient of the

$$ \tilde{R} $$

R
˜

2 term). In realistic models ξ1 must be classically tuned ξ1 ≪ ξ0. We comment on the quantum stability of this value.
Complexity-action of subregions with corners
Authors: Caceres Elena , Xiao Ming-Lei
Published: March 2019

Abstract

In the past, the study of the divergence structure of the holographic entanglement entropy on singular boundary regions uncovered cut-off independent coefficients. These coefficients were shown to be universal and to encode important field theory data. Inspired by these lessons we study the UV divergences of subregion complexity-action (CA) in a region with corner (kink). We develop a systematic approach to study all the divergence structures, and we emphasize that the counter term that restores reparameterization invariance on the null boundaries plays a crucial role in simplifying the results and rendering them more transparent. We find that a general form of subregion CA contains a part dependent on the null generator normalizations and a part that is independent of them. The former includes a volume contribution as well as an area contribution. We comment on the origin of the area term as entanglement entropy, and point out that its presence constitutes a robust difference between the two prescriptions to calculate subregion complexity (-action vs. -volume). We also find universal log δ divergence associated with the kink feature of the subregion. Similar flat angle limit as the subregion-CV result is obtained.
Spinning extensions of D(2, 1; α) superconformal mechanics
Authors: Galajinsky Anton , Lechtenfeld Olaf
Published: March 2019

Abstract

As is known, any realization of SU(2) in the phase space of a dynamical system can be generalized to accommodate the exceptional supergroup D(2, 1; α), which is the most general

$$ \mathcal{N} $$

N

= 4 supersymmetric extension of the conformal group in one spatial dimension. We construct novel spinning extensions of D(2, 1; α) superconformal mechanics by adjusting the SU(2) generators associated with the relativistic spinning particle coupled to a spherically symmetric Einstein-Maxwell background. The angular sector of the full superconformal system corresponds to the orbital motion of a particle coupled to a symmetric Euler top, which represents the spin degrees of freedom. This particle moves either on the two-sphere, optionally in the external field of a Dirac monopole, or in the SU(2) group manifold. Each case is proven to be superintegrable, and explicit solutions are given.
Songs from the Hunters’ Qur’an: Dozo Music, Textuality, and Islam in Northwestern Côte d’Ivoire, from the Repertoire of Dramane Coulibaly
Authors: Hellweg Joseph
Published: March 2019

The hunting songs of the majority-Muslim, Odienné region of Northwestern Côte d’Ivoire accomplish more than meets the ear. They conjoin and distinguish Muslim goals and ostensibly non-Muslim hunting practices. The musical repertoire of my host, Dramane Coulibaly, is illustrative. This study examines the role that Dramane’s songs played in motivating initiated dozo hunters to kill game during dozo funerals, a primary concern for dozos at these events. Next, it analyzes the structure and content of Dramane’s songs in relation to the embodied, emplaced, and material dimensions of dozo funerals, where Dramane’s performances served to calm the spirits of the dead so that they would leave the living in peace. Finally, it examines the musical aspects of Dramane’s songs in relation to Islam, with the aim of broadening the study of Islam in West Africa and beyond to encompass the texts and performance practices of dozo funerals.
Youth Struggles: From the Arab Spring to Black Lives Matter & Beyond
Authors: Honwana Alcinda Manuel
Published: March 2019

The majority of young people in Africa are today living in “waithood,” a prolonged, difficult, and dynamic transition into adult life. This experience is shared with an increasing number of young people in the developed North who are also grappling with issues of joblessness and political exclusion. This waithood generation is increasingly losing faith in the ability of its leaders to address young people’s needs and expectations, and it is rebelling against the status quo. From the youth uprisings that led to the Arab Spring and the ousting of Abdoulaye Wade in Senegal and Campaore in Burkina Faso, to political protest movements such as Occupy Wall Street and Black Lives Matter in the U.S. andLos Indignadosin Spain, young people have been at the forefront of political change. However, they have not yet been able to effect systemic change. While profound social transformation takes time, this generation is still wrestling with how to move beyond street protest and have a lasting impact on politics and governance.
Performing Tradition while Doing Politics: A comparative study of the dozos and koglweogos self-defense movements in Burkina Faso
Authors: Hagberg Sten
Published: March 2019

This article is about self-defense movements in Burkina Faso, with an emphasis on the interplay of political pragmatics and cultural representation in public debate. It examines how two different self-defense movements—the dozos and the koglweogos—articulate tradition and politics with respect to locally organized self-defense in present-day Burkina Faso. In addition to a description of these movements, this comparative study of self-defense movements adds the important dimension of political rivalry and antagonism between the movements under study. First, it demonstrates how the state has tried to contain self-defense movements. Second, the emergence of koglweogos is analyzed with respect to public debate, as well as the state’s attempts to contain the movement bureaucratically. Third, it describes how dozos and koglweogos seek to assert public authority in “the new Burkina Faso” that has taken shape since the fall of Blaise Compaoré in October, 2014. More specifically, this article is devoted to the conflictual relationship between the dozos and the koglweogos that was publicly enacted in late 2016 and early 2017. Self-defense movements must not only be locally and traditionally legitimate, but they also need to be responsible actors in the national political space. Hence, “performing tradition, while doing politics” simultaneously represents the political containment and the cultural legitimacy of the self-defense movements.
German citizenship law and the Turkish diaspora
Authors: McFadden Susan Willis
Published: March 2019

People of Turkish ethnicity constitute Germany’s largest immigrant group but only a small percentage have naturalized as German citizens This article explores the historical foundation of Turkish migration to Germany and the legislative attempts made by both Germany and Turkey to accommodate these people with one foot in each country. It argues that only by abandoning its long-held prejudice against dual citizenship can Germany increase the naturalization rate of all foreigners in its country, not just those from Turkey.
Role of magnetic field evolution on filamentary structure formation in intense laser–foil interactions
Authors: King M. , Butler N. M. H. , Wilson R. , Capdessus R. , Gray R. J. , Powell H. W. , Dance R. J. , Padda H. , Gonzalez-Izquierdo B. , Rusby D. R. , Dover N. P. , Hicks G. S. , Ettlinger O. C. , Scullion C. , Carroll D. C. , Najmudin Z. , Borghesi M. , Neely D. , McKenna P.
Published: March 2019

Filamentary structures can form within the beam of protons accelerated during the interaction of an intense laser pulse with an ultrathin foil target. Such behaviour is shown to be dependent upon the formation time of quasi-static magnetic field structures throughout the target volume and the extent of the rear surface proton expansion over the same period. This is observed via both numerical and experimental investigations. By controlling the intensity profile of the laser drive, via the use of two temporally separated pulses, both the initial rear surface proton expansion and magnetic field formation time can be varied, resulting in modification to the degree of filamentary structure present within the laser-driven proton beam.
The vanishing of strong turbulent fronts in bent pipes
Authors: Rinaldi Enrico , Canton Jacopo , Schlatter Philipp
Published: March 2019

Isolated patches of turbulence in transitional straight pipes are sustained by a strong instability at their upstream front, where the production of turbulent kinetic energy (TKE) is up to five times higher than in the core. Direct numerical simulations presented in this paper show no evidence of such strong fronts if the pipe is bent. We examine the temporal and spatial evolution of puffs and slugs in a toroidal pipe with pipe-to-torus diameter ratio$\unicode[STIX]{x1D6FF}=D/d=0.01$at several subcritical Reynolds numbers. Results show that the upstream overshoot of TKE production is at most one-and-a-half times the value in the core and that the average cross-flow fluctuations at the front are up to three times lower if compared to a straight pipe, while attaining similar values in the core. Localised turbulence can be sustained at smaller energies through a redistribution of turbulent fluctuations and vortical structures by the in-plane Dean motion of the mean flow. This asymmetry determines a strong localisation of TKE production near the outer bend, where linear and nonlinear mechanisms optimally amplify perturbations. We further observe a substantial reduction of the range of Reynolds numbers for long-lived intermittent turbulence, in agreement with experimental data from the literature. Moreover, no occurrence of nucleation of spots through splitting could be detected in the range of parameters considered. Based on the present results, we argue that this mechanism gradually becomes marginal as the curvature of the pipe increases and the transition scenario approaches a dynamical switch from subcritical to supercritical.
EXPLICIT cocycle formulas on finite abelian groups with applications to braided linear Gr-categories and Dijkgraaf–Witten invariants
Authors: Huang Hua-Lin , Wan Zheyan , Ye Yu
Published: March 2019

We provide explicit and unified formulas for the cocycles of all degrees on the normalized bar resolutions of finite abelian groups. This is achieved by constructing a chain map from the normalized bar resolution to a Koszul-like resolution for any given finite abelian group. With a help of the obtained cocycle formulas, we determine all the braided linear Gr-categories and compute the Dijkgraaf–Witten Invariants of then-torus for alln.
Iron status and associations with physical performance during basic combat training in female New Zealand Army recruits
Authors: Martin Nicola M. , Conlon Cathryn A. , Smeele Rebecca J. M. , Mugridge Owen A. R. , von Hurst Pamela R. , McClung James P. , Beck Kathryn L.
Published: March 2019

Decreases in Fe status have been reported in military women during initial training periods of 8–10 weeks. The present study aimed to characterise Fe status and associations with physical performance in female New Zealand Army recruits during a 16-week basic combat training (BCT) course. Fe status indicators – Hb, serum ferritin (sFer), soluble transferrin receptor (sTfR), transferrin saturation (TS) and erythrocyte distribution width (RDW) – were assessed at the beginning (baseline) and end of BCT in seventy-six volunteers without Fe-deficiency non-anaemia (sFer <12 µg/l; Hb ≥120 g/l) or Fe-deficiency anaemia (sFer <12 µg/l; Hb <120 g/l) at baseline or a C-reactive protein >10 mg/l at baseline or end. A timed 2·4 km run followed by maximum press-ups were performed at baseline and midpoint (week 8) to assess physical performance. Changes in Fe status were investigated using paired t tests and associations between Fe status and physical performance evaluated using Pearson correlation coefficients. sFer (56·6 (sd 33·7) v. 38·4 (sd 23·8) µg/l) and TS (38·8 (sd 13·9) v. 34·4 (sd 11·5) %) decreased (P<0·001 and P=0·014, respectively), while sTfR (1·21 (sd 0·27) v. 1·39 (sd 0·35) mg/l) and RDW (12·8 (sd 0·6) v. 13·2 (sd 0·7) %) increased (P<0·001) from baseline to end. Hb (140·6 (sd 7·5) v. 142·9 (sd 7·9) g/l) increased (P=0·009) during BCT. At end, sTfR was positively (r 0·29, P=0·012) and TS inversely associated (r –0·32, P=0·005) with midpoint run time. There were no significant correlations between Fe status and press-ups. Storage and functional Fe parameters indicated a decline in Fe status in female recruits during BCT. Correlations between tissue-Fe indicators and run times suggest impaired aerobic fitness. Optimal Fe status appears paramount for enabling success in female recruits during military training.
DOING DEVELOPMENT-ORIENTED AGRONOMY: RETHINKING METHODS, CONCEPTS AND DIRECTION
Authors: ANDERSSON JENS A. , GILLER KEN E.
Published: March 2019

This special issue brings together a selection of papers that not merely present agronomic research findings, but critically review orientations, methodologies and research practices in agronomy. The focus is on agronomic research as it conducted as component of rural development efforts in the global South or, in short, development-oriented agronomy. Aiming to contribute to development challenges like food security, human welfare and wellbeing, and environmental sustainability, a focus on development-oriented agronomy implies a step beyond a narrow understanding of agronomy as the science of crop production and soil management. Doing development-oriented agronomy forefronts the juggling with productivity enhancing, environmental and social developmental goals entailed when doing agronomy. What is more, development-oriented agronomy generally takes place within a complex environment of (inter)national research and development policy organisations, development donor-funded projects, governmental, NGO and private sector agencies and global professional networks and (public–private) partnerships. Consequently, development-oriented agronomy is a field where debate and contestations over goals and direction, research methodologies and findings of agronomic research are first likely to emerge and become apparent.
Improving soil phosphorus supply and wheat yield with manure-amended phosphate fertilizer
Authors: Akhtar Muhammad , Ikram Wasiq , Mahmood Tariq , Yousaf Sundas , Waqas Gillani Syed M. , Ejaz Amjad
Published: March 2019

Mixing of phosphate fertilizer with farmyard manure (FYM) is a simple technique for optimizing phosphorus (P) availability and then improving the productivity of wheat (Triticum aestivum) grown in alkaline calcareous soils. Diammonium phosphate (DAP) and phosphoric acid (PA) were applied to soil at 36 mg P kg−1, either as sole or after amending 1-g P fertilizer with 2-g FYM (1:2, w/w basis). After 45-day incubation, concentration of P ions in the soil solution (Cp) and exchangeable P present in soil solid (E-value) were determined to evaluate the amount of total plant-available pool. The FYM-amended fertilizers, i.e., PA+FYM and DAP+FYM, showed higher E-values, i.e., 114 and 97 mg kg−1 soil, respectively. Similarly, PA+FYM exhibited the highest proportion of P derived from fertilizer (Pdff = 51.5%) and induced the highest P uptake by wheat seedlings (L-value = 72.1 mg kg−1). Consequently, PA+FYM and DAP+FYM treatments caused higher grain yield and P-use efficiency. The regression analysis revealed strong and positive correlation between L-value and grain yield (r = 0.86), biomass production (r = 0.84) and P-use efficiency (r = 0.87) by wheat crop. Results suggested that FYM-amended inorganic P fertilizer can be a promising technique to optimize supply of P from soil, improve efficiency of inorganic P fertilizers, and improve wheat yield in alkaline calcareous soils.
Interference of weeds in vegetable crop cultivation, in the changing climate of Southern Europe with emphasis on drought and elevated temperatures: a review
Authors: Karkanis A. , Ntatsi G. , Alemardan A. , Petropoulos S. , Bilalis D.
Published: March 2019

It is challenging to predict the changes in weed flora that may occur because of changes in global climate. Limited data are available on the effect of climate change and drought conditions on weed flora and their competitiveness in Southern Europe. Future predictions by scientists indicate reduced and untimely rainfall, along with increased temperatures in this region. Weeds possess a variety of developmental and physiological mechanisms, including senescing, increased leaf cuticular wax deposition, well-developed palisade parenchyma in the leaves, high root/shoot ratio, stomatal closure, peroxidase accumulation and symbiosis with endophytes that enable them to adapt to drought and high temperatures. Because of high adaptability of weeds to adverse environmental conditions, it can be assumed that under future warmer and drier environmental conditions, their growth will be favoured, while the competitiveness of vegetable crops against weeds will be decreased. It is important to highlight that the predicted decrease in overall rainfall levels throughout the year may lead to increased problems of herbicide residues (carryover effects) to following crops. The current paper provides an up-to-date overview of the adaptation mechanisms of weed species commonly found in Southern Europe, in order to expand the available knowledge regarding their response to drought and elevated temperatures. Emphasis is placed on revealing the effects of drought and increased temperatures on vegetable–weed competition and, most importantly, its effect on vegetable crop yield.
Neuropsychological deficits in participants at clinical high risk for psychosis recruited from the community: relationships to functioning and clinical symptoms
Authors: Haining Kate , Matrunola Claire , Mitchell Lucy , Gajwani Ruchika , Gross Joachim , Gumley Andrew I. , Lawrie Stephen M. , Schwannauer Matthias , Schultze-Lutter Frauke , Uhlhaas Peter J.
Published: March 2019

Background

The current study examined the pattern of neurocognitive impairments in a community-recruited sample of clinical high-risk (CHR) participants and established relationships with psychosocial functioning.

Methods

CHR-participants (n = 108), participants who did not fulfil CHR-criteria (CHR-negatives) (n = 42) as well as a group of healthy controls (HCs) (n = 55) were recruited. CHR-status was assessed using the Comprehensive Assessment of At-Risk Mental States (CAARMS) and the Schizophrenia Proneness Instrument, Adult Version (SPI-A). The Brief Assessment of Cognition in Schizophrenia Battery (BACS) as well as tests for emotion recognition, working memory and attention were administered. In addition, role and social functioning as well as premorbid adjustment were assessed.

Results

CHR-participants were significantly impaired on the Symbol-Coding and Token-Motor task and showed a reduction in total BACS-scores. Moreover, CHR-participants were characterised by prolonged response times (RTs) in emotion recognition as well as by reductions in both social and role functioning, GAF and premorbid adjustments compared with HCs. Neurocognitive impairments in emotion recognition accuracy, emotion recognition RT, processing speed and motor speed were associated with several aspects of functioning explaining between 4% and 12% of the variance.

Conclusion

The current data obtained from a community sample of CHR-participants highlight the importance of dysfunctions in motor and processing speed and emotion recognition RT. Moreover, these deficits were found to be related to global, social and role functioning, suggesting that neurocognitive impairments are an important aspect of sub-threshold psychotic experiences and a possible target for therapeutic interventions.
“The Great Humanitarian”: The Soviet Union, the International Committee of the Red Cross, and the Geneva Conventions of 1949
Authors: van Dijk Boyd
Published: March 2019

The Geneva Conventions of 1949 are often seen as the product of Western European design and liberal humanitarianism. Based on a collection of Western and Soviet archival materials, this article reveals the Soviet delegation's mixed but critical legacy in developing the Conventions. The Soviets, acting in surprisingly close cooperation with the International Committee of the Red Cross (ICRC), were essential for supporting a range of groundbreaking plans to end ‘inhumane’ measures in war, from unrestrained colonial warfare to inhumane treatment. They made however some of these protections vulnerable due to their opposition to accepting stronger enforcement mechanisms, such as allowing the ICRC and Protecting Powers to visit their Gulag archipelago. By doing so, the Soviets helped to create the foundations for both the successes and failures of the Geneva Conventions.
Campylobacter jejuni capsule types in a Peruvian birth cohort and associations with diarrhoeal disease severity
Authors: Neitenbach Britney , Poly Frédéric , Kuroiwa Janelle , Burga Rosa , Olortegui Maribel Paredes , Guerry Patricia , Kosek Margaret , Porter Chad K.
Published: March 2019

Campylobacter jejuni is a leading cause of bacterial diarrhoea worldwide. The objective of this study was to examine the association between C. jejuni capsule types and clinical signs and symptoms of diarrhoeal disease in a well-defined birth cohort in Peru. Children were enrolled in the study at birth and followed until 2 years of age as part of the Malnutrition and Enteric Infections birth cohort. Associations between capsule type and clinical outcomes were assessed using the Pearson's χ2 and the Kruskal–Wallis test statistics. A total of 318 C. jejuni samples (30% from symptomatic cases) were included in this analysis. There were 22 different C. jejuni capsule types identified with five accounting for 49.1% of all isolates. The most common capsule types among the total number of isolates were HS4 complex (n = 52, 14.8%), HS5/31 complex (n = 42, 11.9%), HS15 (n = 29, 8.2%), HS2 (n = 26, 7.4%) and HS10 (n = 24, 6.8%). These five capsule types accounted for the majority of C. jejuni infections; however, there was no significant difference in prevalence between symptomatic and asymptomatic infection (all p > 0.05). The majority of isolates (n = 291, 82.7%) were predicted to express a heptose-containing capsule. The predicted presence of methyl phosphoramidate, heptose or deoxyheptose on the capsule was common.
Comparing the epidemiology of community- and hospital-associatedClostridium difficileinfections in Northern Ireland, 2012–2016: a population data linkage and case–case study
Authors: Maisa A. , Ross G. , Verlander N.Q. , Fairley D. , Bradley D.T. , Patterson L.
Published: March 2019

The burden of community-associatedClostridium difficileinfection (CA-CDI) has increased. We aimed to describe the epidemiology of CA-CDI to inform future interventions. We used population-based linked surveillance data from 2012 to 2016 to describe socio-demographic factors, ribotype and mortality for all CA (n= 1303) and hospital-associated (HA,n= 1356) CDI. For 483 community-onset (CO) CA-CDI and 287 COHA-CDI cases, a questionnaire on risk factors was completed and we conducted a case–case study using logistic regression models for univariate and multivariable analysis. CA-CDI cases had lower odds of being male (adjusted odds ratio (AOR) 0.71, 95% confidence interval (CI) 0.58–0.87;P< 0.001), and higher odds of living in rural rather than urban settlement (AOR 1.5, 95% CI 1.1–2.1;P= 0.05) compared with HA-CDI cases. The distribution of ribotypes was similar in both groups with RT078 being most prevalent. CDI-specific death was lower in CA-CDI than HA-CDI (7%vs.11%,P< 0.001). COCA-CDI had lower odds of having had an outpatient appointment in the previous 4 weeks compared with COHA-CDI (AOR 0.61; 95% CI 0.41–0.9,P= 0.01) and lower odds of being in a care home or hospice when compared with their own home, than COHA-CDI (AOR 0.66; 95% CI 0.45–0.98 and AOR 0.35; 95% CI 0.13–0.92,P= 0.02). Exposure to gastric acid suppressants (50% in COCA-CDI and 55% in COHA-CDI) and antimicrobial therapy (18% in COCA-CDI and 20% in COHA-CDI) prior to CDI was similar. Our analysis of community-onset cases suggests that other risk factors for COHA-CDI may be equally important for COCA-CDI. Opportunities to safely reduce antibiotic and gastric acid suppressants use should be investigated in all healthcare settings.
Rice scarcity in World War II Macao: the local experience revisited
Authors: VIANA VENUS , KIM KYUNG YEOB
Published: March 2019

After Hong Kong fell on Christmas Day 1941, the ongoing war threatened life in isolated, neutral Macao. While many scholars have attributed the local people's starvation and suffering to the war, others have highlighted Macao's economic prosperity. To explain the gap between these two narratives, this article explores how the locals dealt with rice scarcity and fared relatively well during the four years of Japanese occupation of the Pearl River Delta. Instead of blaming the shortage solely on the machinations of the Japanese and the rice merchants, we uncover the local people's actions in exacerbating the problem.
Negotiating Women in Egypt's Post-Mubarak Constitutions (2012–2014)
Authors: Tadros Mariz
Published: March 2019

This paper presents a comparative “gender audit” of Egypt's two constitutions (2012, 2014) developed after a people's uprising in 2011 and 2013 led to the ousting of two presidents (Mubarak and Morsi respectively). Egypt's two constitutions are particularly compelling for the study of gender politics in transitional constitutionalism because while the number of women participating in the constitution writing process was very similar, the gendered outcomes were starkly different. While the political opportunity for mobilizing around women's rights was enhanced in the aftermath of Mubarak's demise, the capitalization of these opportunities by organized political forces with an anti-feminist agenda undermined the prospects of en-gendering the first post-Mubarak constitution. In contrast, the constitution of 2014, developed under severely circumscribed political space inhibiting women's mobilization, witnessed the exercise of women's constitutional agency to redress the containment of women's rights under the previous constitution and en-gender many elements of it, though the extent of its enforceability remains obscure. This paper draws on primary and secondary data to analyse, through a gender lens, the processes and outcomes involved in constitution drafting along three axes:context and political opportunity structures; coalitional politics, and political and ideological struggles.
Soybean and common ragweed (Ambrosia artemisiifolia) growth in monoculture and mixture
Authors: Barnes Ethann R. , Jhala Amit J. , Knezevic Stevan Z. , Sikkema Peter H. , Lindquist John L.
Published: March 2019

Understanding how plants alter their growth in response to interplant competition is an overlooked but complex problem. Previous studies have characterized the effect of light and water stress on soybean or common ragweed growth in monoculture, but no study has characterized soybean and common ragweed growth in mixture. A field study was conducted in 2015 and 2016 at the University of Nebraska-Lincoln to characterize the growth response of soybean and common ragweed with different irrigation levels and intraspecific and interspecific interference. The experiment was arranged in a split-plot design with irrigation level (0, 50%, 100% replacement of simulated evapotranspiration) as the main plot and common ragweed density (0, 2, 6, 12 plants m−1 row) as the subplot. Crop- and weed-free controls and three mixture treatments were included as subplots. Periodic destructive samples of leaf area and biomass of different organ groups were collected, and leaf area index (LAI), aboveground biomass partitioning, specific leaf area (SLA), and leaf area ratio (LAR) were calculated. Additionally, soybean and common ragweed yield were harvested, and 100-seed weight and seed production were determined. Soybean did not alter biomass partitioning, SLA, or LAR in mixture with common ragweed. Soybean LAI, biomass, and seed size were affected by increasing common ragweed density. Conversely, common ragweed partitioned less new biomass to leaves and increased SLA in response to increased interference. Common ragweed LAI, biomass, and seed number were reduced by the presence of soybean and increasing common ragweed density; however, seed weight was not affected. Results show that adjustment in biomass partitioning, SLA, and LAR is not the method that soybean uses to remain plastic under competition for light. Common ragweed demonstrated plasticity in both biomass partitioning and SLA, indicating an ability to maintain productivity under intra- and inter-specific competition for light or soil resources.
Response of weedy rice (Oryzaspp.) germplasm from Arkansas to glyphosate, glufosinate, and flumioxazin
Authors: Shrestha Swati , Sharma Gourav , Burgos Nilda Roma , Tseng Te-Ming
Published: March 2019

Weedy rice (Oryzaspp.) is one of the most competitive weeds in rice (Oryza sativaL.) production. Rapid growth, high tillering, enhanced ability to uptake fertilizers, asynchronous maturation, seed shattering, and high seedbank longevity makeOryzaspp. more competitive than cultivated rice and highly persistent.Oryzaspp. may be a source of useful traits for crop improvement such as herbicide tolerance. Greenhouse studies were conducted to evaluate the response of 54Oryzaspp. accessions collected between 2008 and 2009 from Arkansas to glyphosate, glufosinate, and flumioxazin applied at field rates. Rice cultivars ‘CL163’ and ‘REX’ were included for comparison. Accessions B20, B2, and S11 and B49, B51, and S59 showed reduced sensitivity to glyphosate and flumioxazin, respectively. These accessions had less than 40% injury 5 wk after treatment (WAT). Rice cultivars (CL163 and REX) were sensitive to both glyphosate and flumioxazin, with more than 95% plant mortality at 5 WAT. On average, blackhull accessions were more tolerant to glyphosate and flumioxazin than strawhull accessions. Dose–response analysis of B20, B2, and S11 confirmed 3- to 8-fold higher tolerance of these accessions to glyphosate. AllOryzaspp. and cultivated rice were not affected by glufosinate applied at 874 g ai ha−1(1X) and were controlled 100% by 1,311 g ai ha−1(1.5X).Oryzaspp. lines with reduced sensitivity to glyphosate and flumioxazin will be studied further for use in rice crop improvement.
Unsupervised Learning Reveals Geography of Global Ocean Dynamical Regions
Authors: Sonnewald Maike , Wunsch Carl , Heimbach Patrick
Published: March 2019

Dynamically similar regions of the global ocean are identified using a barotropic vorticity (BV) framework from a 20‐year mean of the Estimating the Circulation and Climate of the Ocean state estimate at 1° resolution. An unsupervised machine learning algorithm,K‐means, objectively clusters the standardized BV equation, identifying five unambiguous regimes. Cluster 1 covers 43 ± 3.3% of the ocean area. Surface and bottom stress torque are balanced by the bottom pressure torque and the nonlinear torque. Cluster 2 covers 24.8 ± 1.2%, where the beta effect balances the bottom pressure torque. Cluster 3 covers 14.6 ± 1.0%, characterized by a “Quasi‐Sverdrupian” regime where the beta effect is balanced by the wind and bottom stress term. The small region of Cluster 4 has baroclinic dynamics covering 6.9 ± 2.9% of the ocean. Cluster 5 occurs primarily in the Southern Ocean. Residual “dominantly nonlinear” regions highlight where the BV approach is inadequate, found in areas of rough topography in the Southern Ocean and along western boundaries.
Outgassing of Mantle Volatiles in Compressional Tectonic Regime Away From Volcanism: The Role of Continental Delamination
Authors: Caracausi Antonio , Sulli Attilio
Published: March 2019

In this study we discuss the occurrence of mantle‐derived heat and volatiles (i.e., helium and CO2) feeding hydrothermal systems in a seismically active margin between two convergent plates (African and European) without any signals of volcanism. The helium (He) isotopes clearly indicate a mantle‐derived component in the outgassing volatiles. The estimated mantle‐derived He fluxes are up to two to three orders of magnitude greater than those in a stable continental area. Such high He fluxes cannot be provided by a long‐lasting diffusion, thereby implying a more efficient transport (i.e., advective transport through faults). He data coupled to heat‐He relationship suggest the occurrence of active degassing of magmatic intrusions in this area of continental collisional. Geophysical data indicate the presence of a hot mantle wedge below the outgassing of mantle volatiles and a system of faults cutting the continental crust down to the hot mantle wedge. Here we discuss the hot mantle wedge and possible associated magmatic intrusions as the source of the mantle‐derived volatiles outgassing in the region. We also assessed the output of mantle‐derived CO2 from the investigated hydrothermal basins. The possible occurrence of magma at depth as well as the geometry of the thick‐skinned deformed wedge unambiguously indicates delamination processes that are related to continental subduction. Hence, we show that delamination processes can really produce magma at depth without evidences of volcanism at the surface. Finally, we have also provided the fault systems that work as a network of pathways and actively sustain the advective transfer of the mantle fluids toward the surface.
Dissolved Organic Nitrogen Production and Export by Meridional Overturning in the Eastern Subpolar North Atlantic
Authors: Fernández‐Castro Bieito , Álvarez Marta , Nieto‐Cid Mar , Zunino Patricia , Mercier Herlé , Álvarez‐Salgado Xosé Antón
Published: March 2019

Dissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we quantify the transport and budget of dissolved organic nitrogen (DON) in the eSPNA, in a box delimited by the OVIDE 2002 section and the Greenland‐Iceland‐Scotland sills. The Meridional Overturning Circulation exports >15.9 TgN/year of DON downward and, contrary to the extended view that these are materials of subtropical origin, up to 33% of the vertical flux derives from a net local DON production of 7.1 ± 2.6 TgN/year. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short transit times in the eSPNA (3 ± 1 year) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.
Time of Detection as a Metric for Prioritizing Between Climate Observation Quality, Frequency, and Duration
Authors: Carter B. R. , Williams N. L. , Evans W. , Fassbender A. J. , Barbero L. , Hauri C. , Feely R. A. , Sutton A. J.
Published: March 2019

We advance a simple framework based on “time of detection” for estimating the observational needs of studies assessing climate changes amidst natural variability and apply it to several examples related to ocean acidification. This approach aims to connect the Global Ocean Acidification Observing Network “weather” and “climate” data quality thresholds with a single dynamic threshold appropriate for a range of potential ocean signals and environments. A key implication of the framework is that measurement frequency can be as important as measurement accuracy, particularly in highly variable environments. Pragmatic cost‐benefit analyses based on this framework can be performed to quantitatively determine which observing strategy will accomplish a given detection goal soonest and resolve a signal with the greatest confidence and to assess how the trade‐offs between measurement frequency and accuracy vary regionally.
Identification of Channeling in Pore‐Scale Flows
Authors: Siena Martina , Iliev Oleg , Prill Torben , Riva Monica , Guadagnini Alberto
Published: March 2019

We quantify flow channeling at the microscale in three‐dimensional porous media. The study is motivated by the recognition that heterogeneity and connectivity of porous media are key drivers of channeling. While efforts in the characterization of this phenomenon mostly address processes at the continuum scale, it is recognized that pore‐scale preferential flow may affect the behavior at larger scales. We consider synthetically generated pore structures and rely on geometrical/topological features of subregions of the pore space where clusters of velocity outliers are found. We relate quantitatively the size of such fast channels, formed by pore bodies and pore throats, to key indicators of preferential flow and anomalous transport. Pore‐space spatial correlation provides information beyond just pore size distribution and drives the occurrence of these velocity structures. The latter occupy a larger fraction of the pore‐space volume in pore throats than in pore bodies and shrink with increasing flow Reynolds number.
Multiyear Measurements of Radiation Belt Electrons: Acceleration, Transport, and Loss
Authors: Baker Daniel N. , Hoxie Vaughn , Zhao Hong , Jaynes Allison N. , Kanekal Shri , Li Xinlin , Elkington Scot
Published: March 2019

In addition to clarifying morphological structures of the Earth's radiation belts, it has also been a major achievement of the Van Allen Probes mission to understand more thoroughly how highly relativistic and ultrarelativistic electrons are accelerated deep inside the radiation belts. Prior studies have demonstrated that electrons up to energies of 10 megaelectron volts (MeV) can be produced over broad regions of the outer Van Allen zone on timescales of minutes to a few hours. It often is seen that geomagnetic activity driven by strong solar storms (i.e., coronal mass ejections, or CMEs) almost inexorably leads to relativistic electron production through the intermediary step of intense magnetospheric substorms. In this study, we report observations over the 6‐year period 1 September 2012 to 1 September 2018. We focus on data about the relativistic and ultrarelativistic electrons (E≥5 MeV) measured by the Relativistic Electron‐Proton Telescope sensors on board the Van Allen Probes spacecraft. This work portrays the radiation belt acceleration, transport, and loss characteristics over a wide range of geomagnetic events. We emphasize features seen repeatedly in the data (three‐belt structures, “impenetrable” barrier properties, and radial diffusion signatures) in the context of acceleration and loss mechanisms. We especially highlight solar wind forcing of the ultrarelativistic electron populations and extended periods when such electrons were absent. The analysis includes new display tools showing spatial features of the mission‐long time variability of the outer Van Allen belt emphasizing the remarkable dynamics of the system.
Validation of the Neutron Monitor Yield Function Using Data From AMS‐02 Experiment, 2011–2017
Authors: Koldobskiy Sergey A. , Bindi Veronica , Corti Claudio , Kovaltsov Gennady A. , Usoskin Ilya G.
Published: March 2019

The newly published spectra of protons and helium over time directly measured in space by the Alpha Magnetic Spectrometer (AMS‐02) experiment for the period 2011–2017 provide a unique opportunity to calibrate ground‐based neutron monitors (NMs). Here, calibration of several stable sea level NMs (Inuvik, Apatity, Oulu, Newark, Moscow, Hermanus, and Athens) was performed using these spectra. Four modern NM yield functions were verified: Mi13 (Mishev et al., 2013, https://doi.org/10.1002/jgra.50325), Ma16 (Mangeard et al., 2016, https://doi.org/10.1002/2016JA023515), CM12 (Caballero‐Lopez & Moraal, 2012, https://doi.org/10.1029/2012JA017794), and CD00 (Clem & Dorman, 2000, https://doi.org/10.1023/A:1026508915269), on the basis of the cosmic ray spectra measured by AMS‐02. The Mi13 yield function was found to realistically represent the NM response to galactic cosmic rays. CM12 yield function leads to a small skew in the solar cycle dependence of the scaling factor. In contrast, Ma16 and CD00 yield functions tend to overestimate the NM sensitivity to low‐rigidity (<10 GV) cosmic rays. This effect may be important for an analysis of ground level enhancements, leading to a potential underestimate of fluxes of solar energetic particles as based on NM data. The Mi13 yield function is recommended for quantitative analyses of NM data, especially for ground level enhancements. The validity of the force field approximation was studied, and it was found that it fits well the directly measured proton spectra, within a few percent for periods of low to moderate activity and up to ≈10% for active periods. The results of this work strengthen and validate the method of the cosmic ray variability analysis based on the NM data and yield function formalism and improve its accuracy.
VIIRS Deep Blue Aerosol Products Over Land: Extending the EOS Long‐Term Aerosol Data Records
Authors: Hsu N. C. , Lee J. , Sayer A. M. , Kim W. , Bettenhausen C. , Tsay S.‐C.
Published: March 2019

A primary goal of the Deep Blue (DB) project is to create consistent long‐term aerosol data records, suitable for climate studies, using multiple satellite instruments. In order to continue Earth Observing System (EOS)‐era aerosol products into the Joint Polar Satellite System era, we have successfully ported the DB algorithm to process data from the Visible Infrared Imaging Radiometer Suite (VIIRS). Although the basic structure of the VIIRS algorithm is similar to that for the Moderate Resolution Imaging Spectroradiometer (MODIS), many enhancements have been made compared to the MODIS collection 6 (C6) version. Most have also been implemented in the latest MODIS Collection 6.1 (C6.1). For example, a new smoke mask was developed based on the spectral curvature of measured reflectance to distinguish biomass burning smoke from weakly absorbing urban/industrial aerosols. Consequently, a new aerosol‐type flag was added into the VIIRS DB data set. In addition, new dust models have been developed to account for the nonsphericity of mineral dust. As a result, a discontinuity in the retrieved aerosol optical depth (AOD) of Saharan dust plumes seen in MODIS C6 products near the boundary between North Africa and the Atlantic has been much reduced. We have also evaluated the VIIRS and MODIS Terra/Aqua C6.1 AOD against Aerosol Robotic Network data. VIIRS and MODIS retrievals show similar performance; around 80% of matchups agree with Aerosol Robotic Network within the expected error of ±(0.05 + 20)%, indicating that DB can provide consistent AOD through the historical EOS and present Joint Polar Satellite System eras.
Uncertainties in Snowpack Simulations—Assessing the Impact of Model Structure, Parameter Choice, and Forcing Data Error on Point‐Scale Energy Balance Snow Model Performance
Authors: Günther Daniel , Marke Thomas , Essery Richard , Strasser Ulrich
Published: March 2019

In this study, we assess the impact of forcing data errors, model structure, and parameter choices on 1‐D snow simulations simultaneously within a global variance‐based sensitivity analysis framework. This approach allows inclusion of interaction effects, drawing a more representative picture of the resulting sensitivities. We utilize all combinations of a multiphysics snowpack model to mirror the influence of model structure. Uncertainty ranges of model parameters and input data are extracted from the literature. We evaluate a suite of 230,000 model realizations at the snow monitoring station Kühtai (Tyrol, Austria, 1,920 m above sea level) against snow water equivalent observations. The results show throughout the course of 25 winter seasons (1991–2015) and different model performance criteria a large influence of forcing data uncertainty and its interactions on the model performance. Mean interannual total sensitivity indices are in the general order of parameter choice < model structure < forcing error, with precipitation, air temperature, and the radiative forcings controlling the variance during the accumulation period and air temperature and longwave irradiance controlling the variance during the ablation period, respectively. Model skill is highly sensitive to the snowpack liquid water transport scheme throughout the whole winter period and to albedo representation during the ablation period. We found a sufficiently long evaluation period (>10 years) is required for robust averaging. A considerable interaction effect was revealed, indicating that an improvement in the knowledge (i.e., reduction of uncertainty) of one factor alone might not necessarily improve model results.
An Integrated Approach Toward Sustainability via Groundwater Banking in the Southern Central Valley, California
Authors: Ghasemizade Mehdi , Asante Kwabena O. , Petersen Christian , Kocis Tiffany , Dahlke Helen E. , Harter Thomas
Published: March 2019

Intensive groundwater withdrawals in California have resulted in depletion of streams and aquifers in some regions. Agricultural managed aquifer recharge (Ag‐MAR) initiatives have recently been piloted in California to mitigate the effects of unsustainable groundwater withdrawals. These initiatives rely on capturing wet‐year water and spreading it on large areas of irrigated agricultural lands to enhance recharge to aquifers. While recharge studies typically consider local effects on aquifer storage, few studies have investigated Ag‐MAR benefits and challenges at a regional scale. Here we used the Integrated Water Flow Model, to evaluate how Ag‐MAR projects can affect streamflows, diversions, pumping, and unsaturated zone flows in the southern Central Valley, California. We further tested the sensitivity of three different spatial patterns of Ag‐MAR, each chosen based on different thresholds of soil suitability, on the hydrologic system. This study investigates how the distribution of Ag‐MAR lands benefit the regional groundwater system and other water balance components. The results suggest that Ag‐MAR benefits vary as a function of the location of Ag‐MAR lands. Stream‐aquifer interactions play a crucial factor in determining the ability to increase groundwater storage in overdrafted basins. The results also indicate that Ag‐MAR projects conducted during the November–April recharge season have implications for water rights outside of the Ag‐MAR season. If not properly monitored, Ag‐MAR can cause a rise of groundwater table into the root zone, negatively impacting sensitive crops. Our work also highlights the benefits of using an integrated hydrologic and management model to evaluate Ag‐MAR at a regional scale.