bluuebunny/crossref_metadata_2025 huggingface dataset:
Variations on the vev flip-flop: instantaneous freeze-out and decaying dark matter
Authors: Baker Michael J. , Mittnacht Lukas
Published: May 2019

Abstract

In this work we consider a simple model for dark matter and identify regions of parameter space where the relic abundance is set via kinematic thresholds, which open and close due to thermal effects. We discuss instantaneous freeze-out, where dark matter suddenly freezes-out when the channel connecting dark matter to the thermal bath closes, and decaying dark matter, where dark matter freezes-out while relativistic and later decays when a kinematic threshold temporarily opens. These mechanisms can occur in the vicinity of a one-step or a two-step phase transition. In all cases thermal effects provide this dynamic behaviour, while ensuring that dark matter remains stable until the present day.
Planar master integrals for four-loop form factors
Authors: von Manteuffel Andreas , Schabinger Robert M.
Published: May 2019

Abstract

We present the complete set of planar master integrals relevant to the calculation of three-point functions in four-loop massless Quantum Chromodynamics. Employing direct parametric integrations for a basis of finite integrals, we give analytic results for the Laurent expansion of conventional integrals in the parameter of dimensional regularization through to terms of weight eight.
Nilpotent networks and 4D RG flows
Authors: Apruzzi Fabio , Hassler Falk , Heckman Jonathan J. , Rochais Thomas B.
Published: May 2019

Abstract

Starting from a general

$$ \mathcal{N}=2 $$

N
=
2

SCFT, we study the network of

$$ \mathcal{N}=1 $$

N
=
1

SCFTs obtained from relevant deformations by nilpotent mass parameters. We also study the case of flipper field deformations where the mass parameters are promoted to a chiral superfield, with nilpotent vev. Nilpotent elements of semi-simple algebras admit a partial ordering connected by a corresponding directed graph. We find strong evidence that the resulting fixed points are connected by a similar network of 4D RG flows. To illustrate these general concepts, we also present a full list of nilpotent deformations in the case of explicit

$$ \mathcal{N}=2 $$

N
=
2

SCFTs, including the case of a single D3-brane probing a D- or E-type F-theory 7-brane, and 6D (G, G) conformal matter compactified on a T
2, as described by a single M5-brane probing a D- or E-type singularity. We also observe a number of numerical coincidences of independent interest, including a collection of theories with rational values for their conformal anomalies, as well as a surprisingly nearly constant value for the ratio a
IR
/c
IR for the entire network of flows associated with a given UV

$$ \mathcal{N}=2 $$

N
=
2

SCFT. The arXiv submission also includes the full dataset of theories which can be accessed with a companion Mathematica script.
Altered expression of insulin‐degrading enzyme and regulator of calcineurin in the rat intracerebral streptozotocin model and human apolipoprotein E‐ε4–associated Alzheimer's disease
Authors: Delikkaya Büşra , Moriel Natalia , Tong Ming , Gallucci Gina , de la Monte Suzanne M.
Published: May 2019

Introduction

This study assesses insulin‐degrading enzyme (IDE) and regulator of calcineurin 1 (RCAN1) as potential mediators of brain insulin deficiency and neurodegeneration in experimental and human Alzheimer's disease (AD).

Methods

Temporal lobes from Long Evans rats treated with intracerebral streptozotocin or vehicle and postmortem frontal lobes from humans with normal aging AD (Braak 0‐2), moderate (Braak 3‐4) AD, or advanced (Braak 5‐6) AD were used to measure IDE and RCAN mRNA and protein.

Results

Intracerebral streptozotocin significantly increased IDE and RCAN mRNA and protein. In humans with apolipoprotein E (ApoE) ε3/ε4 or ε4/ε4 and AD, IDE was elevated at Braak 3‐4, but at Braak 5‐6, IDE expression was significantly reduced. RCAN1 mRNA was similarly reduced in ApoE ε4+ patients with moderate or severe AD, whereas RCAN1 protein declined with the severity of AD and ApoE ε4 dose.

Discussion

The findings suggest that IDE and RCAN1 differentially modulate brain insulin signaling in relation to AD severity and ApoE genotype.
“To Shave or Not to Shave”: Pubic Hair Removal and Its Association with Relational and Sexual Satisfaction in Women and Men
Authors: Enzlin Paul , Bollen Kaat , Prekatsounaki Sofia , Hidalgo Liesbeth , Aerts Leen , Deprest Jan
Published: May 2019

Background

Pubic hair removal (PHR) is a widespread practice that entails certain health risks; however, there remains a lack of scientific information on the prevalence and antecedents of PHR, as well as on its association with sexual behavior and relational satisfaction.

Aims

To explore women’s and men’s attitudes regarding PHR and their PHR practices and the associations with demographic, relational, and sexual characteristics.

Methods

A total of 2,687 men and 1,735 women living in Flanders (the Northern part of Belgium) completed an online survey. Participants ranged in age from 15 to 60+ years; they self-identified as heterosexual, bisexual, or homosexual and reported various relationship statuses.

Main Outcome Measures

Demographic items (ie, age, religion, partner relationship status), sexuality-related items (ie, sexual activity, sexual orientation, age at first intercourse, number of sexual partners), PHR items (ie, reasons, inclination to have or not have sex after PHR, perceived partner preferences, partner’s PHR), and relationship satisfaction, assessed with the Maudsley Marital Questionnaire.

Results

Fewer men (39.1%) than women (80.3%) reported (partially) removing their pubic hair. In both men and women, the practice was associated with age, sexual activity, relationship status, and partner’s PHR practice and expectations. In men, sexual and relationship satisfaction were correlated with their partner’s PHR practices and whether these were in line with the men’s expectations. In women, sexual and relationship satisfaction were mostly correlated with whether both partner’s expectations were met. Although both men and women reported that the reasons for PHR were related to their sexual experiences and to their partner’s preference, only women reported that PHR was a way to enhance feelings of femininity. Finally, the reasons for not engaging in PHR were related to partner preferences and side effects.

Conclusion

PHR is a widespread practice and seems strongly associated with personal, partner-related, sexual, and relational factors. Strategies to prevent men and women from being confronted with health risks should take all these factors into account.
Are There Differences in Brain Morphology in Patients with Lifelong Premature Ejaculation?
Authors: Atalay Hasan Anil , Sonkaya Ali Riza , Ozbir Sait , Culha Mehmet Gokhan , Degirmentepe Burak , Bayraktarli Recep , Canat Lutfi
Published: May 2019

Introduction

Even though lifelong premature ejaculation (PE) is highly prevalent, few studies have investigated the neural mechanisms underlying PE.

Aim

This study aimed to investigate whether patients with lifelong PE exhibit macrostructural or microstructural alterations of the parts of the brain involved in the male sexual response.

Materials and Methods

We enrolled 42 healthy participants and 54 lifelong PE patients. Lifelong PE was diagnosed according to the Premature Ejaculation Diagnostic Tool (PEDT) and intravaginal ejaculation latency time (IELT). We compared measures of cortical morphology, such as volumes of gray matter, white matter, cerebellum volumes, and subcortical structures (ie, amygdala, caudate, hippocampus, globus pallidus, putamen, and thalamus) between the groups using a voxel-based morphometry method from whole-brain T1-weighted magnetic resonance imaging. Moreover, we evaluated the relationships between the relevant cerebral alterations and the severity of symptoms obtained from participants via self-reported questionnaires.

Main Outcome Measures

Cerebral macrostructural and microstructural alterations were assessed in PE patients and controls, along with the correlation of caudate nucleus changes in PE patients with clinical data (including the PEDT and the IELT).

Results

The mean volume of the caudate nucleus was significantly larger in the lifelong PE patients compared with healthy controls (P = .048). Moreover, caudate nucleus volume was positively correlated with PEDT score (r = 0.621; P = .0179) and negatively correlated with the IELT (r = −0.592; P = .0101). However, cortex morphology and the other subcortical volumes were not significantly different between the 2 groups (P > .05).

Clinical Implications

Microstructural alterations in deep gray matter nuclei might be a useful parameter for studying the mechanism of the neurobiology underlying PE.

Strengths and Limitations

There are few studies examining microstructural changes in PE patients. This study furthers our understanding of the etiology of PE. Limitations include the small sample, which limits our ability to make an absolute determination as to whether such subcortical changes are the cause or the consequence of lifelong PE.

Conclusions

We found a significant difference in caudate nucleus volume between patients with PE and healthy controls. In addition, the caudate nucleus volume was positively associated with the severity of PE symptoms. More extensive and possibly longitudinal studies are needed to improve our understanding of the mechanism of the neurobiology underlying PE.
Use of whole-genome sequencing to guide a Clostridioides difficile diagnostic stewardship program
Authors: Jakharia Kunal K. , Ilaiwy Ghassan , Moose Siobhan S. , Waga Masashi , Appalla Lakshmi , McAlduff Joel D. , Karanfil Lynne V. , McGann Patrick T. , Wortmann Glenn W.
Published: May 2019

Whole-genome sequencing (WGS) has yielded new insights into the transmission patterns of healthcare facility-onset Clostridioides difficile infection (HO-CDI). WGS results prompted a focused diagnostic stewardship program, which was associated with a significant and sustained decrease in HO-CDI at large, urban hospital.
Intermittency in free vibration of a cylinder beyond the laminar regime
Authors: Navrose  , Mittal Sanjay
Published: May 2019

Vortex-induced vibration of a circular cylinder that is free to move in the transverse ($Y$) and streamwise ($X$) directions is investigated at subcritical Reynolds numbers ($1500\lesssim Re\lesssim 9000$) via three-dimensional (3-D) numerical simulations. The mass ratio of the system for all the simulations is $m^{\ast }=10$. It is observed that while some of the characteristics associated with the $XY$-oscillation are similar to those of the $Y$-only oscillation (in line with the observations made by Jauvtis & Williamson (J. Fluid Mech., vol. 509, 2004, pp. 23–62)), notable differences exist between the two systems with respect to the transition between the branches of the cylinder response in the lock-in regime. The flow regime between the initial and lower branch is characterized by intermittent switching in the cylinder response, aerodynamic coefficients and modes of vortex shedding. Similar to the regime of laminar flow, the system exhibits a hysteretic response near the lower- and higher-$Re$ end of the lock-in regime. The frequency spectrum of time history of the cylinder response shows that the most dominant frequency in the streamwise oscillation on the initial branch is the same as that of the transverse oscillation.
Semi-automated open water iceberg detection from Landsat applied to Disko Bay, West Greenland
Authors: SCHEICK JESSICA , ENDERLIN ELLYN M. , HAMILTON GORDON
Published: May 2019

Changes in Greenland's marine-terminating outlet glaciers have led to changes in the flux of icebergs into Greenland's coastal waters, yet icebergs remain a relatively understudied component of the ice-ocean system. We developed a simple iceberg delineation algorithm for Landsat imagery. A machine learning-based cloud mask incorporated into the algorithm enables us to extract iceberg size distributions from open water even in partially cloudy scenes. We applied the algorithm to the Landsat archive covering Disko Bay, West Greenland, to derive a time series of iceberg size distributions from 2000–02 and 2013–15. The time series captures a change in iceberg size distributions, which we interpret as a result of changes in the calving regime of the parent glacier, Sermeq Kujalleq (Jakobshavn Isbræ). The change in calving style associated with the disintegration and disappearance of Sermeq Kujalleq's floating ice tongue resulted in the production of more small icebergs. The increased number of small icebergs resulted in increasingly negative power law slopes fit to iceberg size distributions in Disko Bay, suggesting that iceberg size distribution time series provide useful insights into changes in calving dynamics.
A Perspective on Ethics and the Reburial Controversy
Authors: Klesert Anthony L. , Powell Shirley
Published: May 2019

It is our opinion that archaeologists have no inherent right of access to human remains, grave goods, or objects of cultural heritage; that respecting diverse cultural views does not amount to an abdication of academic freedom; that historically archaeologists have been unanthropological in their approach to living populations and inconsistent in their treatment of indigenous peoples; and that archaeologists are fighting a losing battle when they ignore public opinion and clash with indigenous groups in the name of science. We offer some guidelines that we feel will alleviate much of the current tensions between archaeologists and indigenous peoples. A professional ethic must be devised that is consciously anthropological, values the rights of those studied and their cultural descendants in their own terms, and places academic pursuits in their proper context.
Organizing for Policy Innovation in Public Bureaucracy: AIDS, Energy and Environmental Policy in Canada
Authors: Desveaux James A. , Lindquist Evert A. , Toner Glen
Published: May 2019

Governments often operate under considerable pressure to respond effectively to the emergence of increasingly complex policy dilemmas. This article first explains some key difficulties in bringing forth comprehensive policy interventions. Despite the ubiquity of social and political constraints to policy innovation, many failures can be attributed to public bureaucracies that are not designed to deal with complex problems, and which all too quickly exceed their policy-making capacities. This study then analyzes why comprehensive policy-making does sometimes occur, and links its occurrence to bureaucratic design factors, arguing that extending organizational capacity for innovation involves more than generous budgets and expertise. The article draws upon, and develops further, Mintzberg's ideas on administrative adhocracy to show how administrative units can be organized to enable bureaucracies to transcend professional compartmentalization and routine; and how structures can be designed for comprehensive policy innovation. The study focuses on Canadian federal bureaucracy, and it is supported by three case studies of recent policy experiments: energy, environment and AIDS.
Welfare Institutions and Foreign Aid: Domestic Foundations of Canadian Foreign Policy
Authors: Thérien Jean-Philippe , Noël Alain
Published: May 2019

This article examines the relationship between Canada's development assistance policy and its welfare state institutions. Through an analysis of the Canadian experience, the article argues that the differences between the social policies of developed countries help to understand the nature of their participation in the international aid regime. Although this hypothesis is not entirely new, it is here refined with the help of the comparative literature on the welfare state, and assessed systematically for Canada. Through this case study, the article explores the extent to which values and principles institutionalized at the domestic level influence foreign policy and the international order.
Condemnation to the Mines in the Later Roman Empire
Authors: Gustafson Mark
Published: May 2019

Lactantius, in his shrill polemical pamphlet De mortibus persecutorum, made the following observation while attacking his principal adversary, the emperor Galerius: “There was no mild punishment with him, not islands, not mines, not prisons; but fire, the cross, and wild beasts were daily and ready at hand.” More than a sign of the times, it is also a measure of his fury that Galerius could make exile, hard labor, and imprisonment seem to be lenient sentences. While one must resist succumbing immediately to credulity, one also must admit that even such hyperbole may have a kernel of truth in it. Lactantius probably assumed—as did many others—that the myriad adjustments to the complex relations between the church and the empire, which were in the process of being engineered by Constantine and his associates, would eliminate the need to inflict such punishments on Christians for religious reasons.
Shale-Facies Microfossils from the Proterozoic Bylot Supergroup, Baffin Island, Canada
Authors: Hofmann H. J. , Jackson G. D.
Published: May 2019

Organic-walled microfossils are reported from the Borden Rift Basin of northern Baffin Island and Bylot Island. The diverse assemblage, obtained by palynological acid maceration, comprises 39 taxa and occurs in fine-grained siliciclastic and carbonate units from all but the two lowermost formations of the Bylot Supergroup; their age is bracketed between 1,270 and 750 Ma. Of 307 samples analyzed from all parts of the basin, 133 yielded identifiable remains. The microbiota comprises the following taxa:Siphonophycus septatum, S. robustum, S. rugosumn. comb.,S. kestron, S. capitaneum, Pellicularia tenera, Polythrichoides lineatus, Obruchevella valdaica, Karamia? sp., opaque filaments,Oscillatoriopsisspp.,Palaeolyngbyasp.,Arctacellularia tetragonalan. comb.,A. ellipsoidea, Chlorogloeaopsis contextan. comb.,C. kanshiensisn. comb.,Navifusa bacillarisn. comb.,N. majensis, N. actinomorphan. comb.,Leiosphaeridia minutissima, L. tenuissima, L. crassa, L. jacutica, L. ternata, Lophosphaeridium granulatum, Valeria lophostriata, Pterospermopsimorpha insolita, Eomicrocystis elegans, E. malgica, Symplassosphaeridiumspp.,Synsphaeridiumspp.,Satka squamifera, Satkaspp.,Coneosphaera arctican. sp.,Coneosphaerasp.,Spumosina rubiginosa, andFabiformis baffinensisn. sp. The taxonPalaeocalothrix divaricatus, present in some macerates, is possibly a modern fungal contaminant. Abundance and taxonomic diversity varies considerably between formations and environments, with the Arctic Bay Formation exhibiting the greatest productivity and species diversity of the seven formations studied, and the transgressive muddy shelf deposits being the most productive of the 11 environments recognized. This microfossil assemblage of predominantly planktonic species has distinctive taxa in common with Middle to Late Riphean sequences in Siberia (Lakhanda and Miroedikha Groups, ca. 950 to 850 Ma), the lower part of the Thule Group (< 1,270 Ma) in northwest Greenland, the Fury and Hecla Group in western Baffin Island, and taxa reported from the upper part of the Bushimay Supergroup in Zaire. On the other hand, some elements in the Bylot Supergroup are more characteristic of Vendian beds on the Russian Platform, indicating longer stratigraphic ranges for such taxa than previously thought. The compositional similarity between the Borden Basin and Siberian sequences supports palinspastic reconstructions juxtaposing Siberia and Laurentia during the middle to late Proterozoic, and the opening of the Poseidon Ocean.
Potential distribution of and priority conservation areas for the Endangered Caatinga howler monkeyAlouatta ululatain north-eastern Brazil
Authors: Freire Filho Robério , Palmeirim Jorge M.
Published: May 2019

The Caatinga of north-eastern Brazil is the largest and most diverse seasonally dry tropical forest in the Americas and is home to numerous endemic species. However, only 1.2% of the area is under full protection, and given the ongoing decline of this biome there is an urgent need to expand the protected area network. The Endangered Caatinga howler monkeyAlouatta ululatais almost endemic to the Caatinga, and is a potential umbrella species for the protection of its biodiversity. Using all available distribution data and our own surveys we appliedMaxentandZonationspatial modelling to identify the range ofA. ululata, and priority conservation areas for the species, maximizing habitat quality and connectivity, and minimizing conservation constraints. The top 10% priority areas cover 34,400 km2and mostly coincide with good remnants of Caatinga. Only priority areas in the northern part of the species’ range are protected, so it is essential to create new protected areas in the centre and south of the range.Maxentmodelling indicates that the species depends on good tree cover, but even inside protected areas we observed recent deforestation, illustrating the urgency to improve management.Maxentalso indicated that aridity limits the species' range, and therefore the ongoing aridification of the Caatinga is a threat to its future. The protection ofA. ululatarequires establishing new protected areas in priority locations and improving management of existing protected areas. Preservation of priority areas for the Caatinga howler monkey also represents an opportunity for the conservation of other important biodiversity in the region.
Semidominant Nature of Monogenic Sulfonylurea Herbicide Resistance in Sugarbeet (Beta vulgaris)
Authors: Hart Stephen E. , Saunders Joseph W. , Penner Donald
Published: May 2019

Greenhouse and laboratory studies were conducted to determine the degree of dominance of the monogenic sulfonylurea herbicide resistance trait in diploid sugarbeet by comparing the response of homozygous and heterozygous resistant sugarbeet to primisulfuron, thifensulfuron, and chlorimuron on the whole plant and acetolactate synthase (ALS) enzyme level. Progeny tests suggested that the monogenic sulfonylurea herbicide resistance was semidominant. Subsequently, heterozygous resistant (R-1) and homozygous resistant (R-2) sugarbeet lines were sprayed with increasing rates of primisulfuron, thifensulfuron, and chlorimuron, and herbicide rates required for 50% growth reduction (GR50) were determined. GR50values were also determined for homozygous susceptible sugarbeet lines (S-1 and S-2). The GR50values indicated that the R-2 sugarbeet was 377, 269, and 144 times more resistant to primisulfuron, thifensulfuron, and chlorimuron, respectively, than susceptible S-2 sugarbeet. In contrast, R-1 sugarbeet was only 107, 76, and 57 times more resistant to primisulfuron, thifensulfuron, and chlorimuron, respectively, than S-1 sugarbeet, indicating at least a twofold difference in the magnitude of resistance between homozygous resistant and heterozygous resistant sugarbeet lines. ALS enzyme activity analysis were consistent with whole plant results. Thus, based on these two, maximum crop resistance can be obtained by developing homozygous resistant cultivars.
Fate of Fenoxaprop-Ethyl Applied to Moisture-Stressed Smooth Crabgrass (Digitaria ischaemum)
Authors: Rossi Frank S. , Di Tomaso Joseph M. , Neal Joseph C.
Published: May 2019

Investigations of smooth crabgrass growth and fenoxaprop-ethyl retention, foliar penetration, translocation, and metabolism were conducted at various soil moisture levels using a polyethylene glycol (PEG) semipermeable membrane system. The activity of fenoxapropethyl was significantly reduced at higher levels of moisture stress and this antagonistic effect was greater with increased duration of water deficit following herbicide application. Fenoxaprop-ethyl spray retention decreased linearly (23% total reduction) as soil matric potential (Ψm) decreased from −0.01 to −0.1 MPa. Foliar penetration and translocation of14C-fenoxaprop-ethyl applied on the third true leaf were not affected by level or duration of moisture stress. Only 2% of the absorbed radioactivity was translocated out of the treated leaf for each moisture stress level and duration. As the soil Ψm decreased (−0.01 to −1.0 MPa) the relative levels of fenoxaprop-ethyl increased by 76 and 65% after a 48- and 96-h postapplication moisture stress period, respectively. In contrast, fenoxaprop acid decreased by 59 and 44% after 48 and 96 h of moisture stress, respectively. The relative level of fenoxaprop acid was linearly correlated to the antagonistic effect on shoot dry weight. These results suggest that decreased spray retention and, particularly, alterations in fenoxaprop-ethyl metabolism contribute to reduced fenoxaprop-ethyl activity observed in moisture-stressed smooth crabgrass.
Jointed Goatgrass (Aegilops cylindrica) Ecology and Interference in Winter Wheat
Authors: Anderson R. L.
Published: May 2019

Jointed goatgrass is a serious weed in winter wheat, and presently no herbicides are available for its selective control. This study examined the effect of time of emergence and removal on jointed goatgrass interference in winter wheat, as well as its rate of development and soil water extraction. The goal of this study was to suggest cultural practices that minimize jointed goatgrass interference in winter wheat. Jointed goatgrass development was identical to ‘Vona’ winter wheat in two crop seasons, even though precipitation differed drastically between seasons. Depth of soil water extraction of both species was also similar. Jointed goatgrass at 18 plants m−2reduced grain yield 27 and 17% when emerging 0 and 42 d after Vona, respectively. The relationship between time of jointed goatgrass emergence after winter wheat and grain yield loss was Y = 30.6–0.29X (X = days, r = 0.72), indicating that plants emerging in late fall still caused yield loss. Removing jointed goatgrass by early March prevented winter wheat grain yield loss. The interference data suggests that producers assess infestation levels and plan control measures in early March.
Flowering Patterns, Seed Production, and Somatic Polymorphism of Three Weed Species
Authors: Senseman Scott A. , Oliver Lawrence R.
Published: May 2019

Field studies determined flowering pattern, seed production, and somatic polymorphism of pitted morningglory, common cocklebur, and sicklepod under interspecific and no interference with soybean. Flowering patterns differed between years but were similar under both interferences. Interspecific interference reduced flower and seed numbers 85 to 99%. Rainfall had little effect on flowering, but photoperiod and temperature responses were evident for all weed species. The production equations for seed number per plant from dry weight were quadratic for pitted morningglory and common cocklebur but linear for sicklepod. All species showed somatic polymorphism; however, differences in seed germination and viability were not consistent between years.
Retreatment with Fall-Applied Herbicides for Canada Thistle (Cirsium arvense) Control
Authors: Donald William W.
Published: May 2019

This field research was designed to compare the long-term effectiveness of late-September applications of several herbicides for reducing Canada thistle shoot density on noncropped, untilled abandoned farmland when reapplied annually for 3 yr. Clopyralid at 560 and 840 g ae ha−1or picloram at 280 and 560 g ae ha−1reduced Canada thistle shoot density as well as either glyphosate3at 0.8 to 2.8 kg ae ha−1or dicamba at 1.1 and 2.2 kg ae ha−1. These treatments were much more effective than 2,4-D at 1.1 and 2.2 kg ae ha−1, chlorsulfuron at 34 and 67 g ai ha−1, and metsulfuron at 34 and 67 g ha−1for progressively reducing Canada thistle shoot density over three annual fall applications. Picloram and clopyralid greatly reduced and delayed shoot emergence from adventitious root buds in spring after two fall-applied treatments compared with nontreated checks.
Interaction of Light, Soil Moisture, and Temperature with Weed Suppression by Hairy Vetch Residue
Authors: Teasdale John R.
Published: May 2019

The influence of light, soil moisture, and temperature on establishment of selected species through hairy vetch residue on the soil surface was investigated under controlled conditions in the greenhouse. Hairy vetch residue at rates ranging from 0 to 616 g m−2had no effect on corn, slightly reduced velvetleaf and green foxtail establishment, and severely inhibited common lambsquarters establishment under full sunlight conditions. The same rates of hairy vetch residue reduced velvetleaf, green foxtail, and common lambsquarters establishment more under a shade cloth with 9% light transmittance than under full sunlight. Day/night temperatures of 24/16 or 32/26 C had no effect and soil moistures of 50 or 133% field capacity had little effect on response of all species to residue rates. Weed establishment was similar under shade cloth without residue as under residue with an equivalent light transmittance, suggesting that light was more important than allelopathy or physical impedance for weed suppression by hairy vetch residue.
Growth Analysis of Weed and Crop Species with Reference to Seed Weight
Authors: Seibert Andrew C. , Pearce R. Brent
Published: May 2019

Growth and morphological characteristics of four weed and two crop species were analyzed to determine how small-seeded weeds can compete with large-seeded crops despite the initial size disadvantage. Small-seeded weeds had higher relative growth rates because of increased percentages of biomass devoted to leaves. This morphological scheme was achieved primarily through a reduction in the percentage of biomass devoted to roots. Yet, small-seeded weeds were able to develop larger mean plant root lengths as a result of having both roots of smaller diameter and higher rates of root length increase.
Persistence of Spotted Knapweed (Centaurea maculosa) Seed in Soil
Authors: Davis Edward S. , Fay Peter K. , Chicoine Timothy K. , Lacey Celestine A.
Published: May 2019

Experiments were established in 1982 to study the loss of viability of spotted knapweed seeds (achenes) in soil. Greater than 50 and 25% of buried seeds remained viable but dormant after 5 and 8 yr at two locations, respectively. Decline in seed viability was also measured in two natural seedbanks. Although the soil seed reserve decreased by 95% over a 7-yr period, approximately 400 000 viable seeds per ha remained, indicating that spotted knapweed seeds will last for many years in soil.
Interaction of White Bean (Phaseolus vulgarisL.) Cultivars, Row Spacing, and Seeding Density with Annual Weeds
Authors: Malik Vikram S. , Swanton Clarence J. , Michaels Tom E.
Published: May 2019

Field experiments were conducted at the Elora Research Station, Elora, Ontario, in 1988 and 1989 to quantify the inherent competitive ability of three white bean cultivars: OAC Gryphon, OAC Sprint, and OAC Laser growing with a naturally occurring population of annual weeds. An attempt was made to increase the competitive ability of these cultivars by altering row spacing and seeding density. Uncontrolled populations of weeds reduced white bean yields by 70%. OAC Gryphon and OAC Laser reduced weed biomass by 10 to 35% compared to OAC Sprint. The ability of cultivars to reduce weed biomass was further enhanced in medium and narrow rows compared to traditional wide rows. Cultivar, row spacing, and seeding density combinations which maximized leaf area index when grown under weedy conditions also had significantly less weed biomass. However, cultivar selection, row spacing, and seeding density did not reduce weed density. A significant negative correlation was observed between weed biomass accumulation and final yield of white bean. For each kg ha−1increase in weed biomass the corresponding white bean yield loss averaged 0.380 kg ha−1. Season-long weed competition significantly reduced total number of pods per plant, number of seeds per pod, and 100-seed weight.
Interaction of Cotton (Gossypium hirsutum) and Velvetleaf (Abutilon theophrasti) Plants for Water is Affected by Their Interaction for Light
Authors: Salisbury Clay D. , Chandler James M.
Published: May 2019

Transpirations of cotton and velvetleaf plants competing for water and light were estimated with heat balance stem flow gauges in a controlled environment. Cotton and velvetleaf plants were grown together in pots and monitored during fluctuations in soil water, irradiance, air temperature, and humidity. Shading from other plants imposed light competition on velvetleaf or cotton. Velvetleaf used significantly more water than cotton given ample water and light. Transpiration by both species was reduced in dry soil, but velvetleaf transpiration was reduced primarily by leaf abscision, while cotton leaves did not abscise. Both cotton and velvetleaf plants transpired significantly less when shaded. Leaf water potentials indicated that shaded plants experienced reduced evaporative demand suggesting that shading reduced plant stress in dry soil. Competition for water was strongly influenced by competition for light.
Seventeen Years of Cropping Systems and Tillage Affect Velvetleaf (Abutilon theophrasti) Seed Longevity
Authors: Lueschen William E. , Andersen Robert N. , Hoverstad Thomas R. , Kanne Brian K.
Published: May 2019

Velvetleaf is difficult to control in corn and soybean and the seed can persist in soil for many years. Seven cultural and tillage practices were established in 1974 on a site heavily infested with velvetleaf to determine the time required to eradicate velvetleaf seed from the soil. A rapid decline in velvetleaf seed population in the top 23 cm of soil occurred during the first 5 yr of this study. In the fifth year, the chemical fallow and continuous alfalfa treatments had 37 and 56% of the original velvetleaf seed population remaining, respectively. In the 17th year, soils in these treatments that had received no tillage since study initiation still contained 15 and 25% of the original velvetleaf seed population, respectively. Systems involving moldboard plowing with continuous-tillage fallow, continuous cropping of corn or oat, or an annual corn and soybean rotation had a more rapid decline in the velvetleaf seed population in soil compared to the chemical fallow and continuous alfalfa treatment. After 17 yr, soil in any system that had received at least one moldboard plowing per year still contained 1 to 3 million velvetleaf seed ha−1, which is only 0.8 to 2.5% of the initial viable seed population. Nearly 100% of the seed remaining in the soil in the 17th year for all treatments was still viable.
Response of a Chlorsulfuron-Resistant Biotype ofKochia scopariato Sulfonylurea and Alternative Herbicides
Authors: Friesen Lyle F. , Morrison Ian N. , Rashid Abdur , Devine Malcolm D.
Published: May 2019

Kochia growing on an industrial site where chlorsulfuron was applied repeatedly over several seasons was confirmed to be resistant to chlorsulfuron and several other acetolactate synthase (ALS) -inhibiting herbicides. In growth room experiments, resistant (R) plants were 2 to >180 times more resistant to five sulfonylurea herbicides and one imidazolinone herbicide (imazethapyr) than susceptible (S) plants, as measured by the ratio of dosages required to inhibit shoot dry matter accumulation by 50% (GR50R/S). Similarly, in vitro assays of ALS activity indicated that from 3 to 30 times more herbicide was required to inhibit the enzyme from R plants than from S plants. Results of ALS enzyme assays indicated that R kochia was approximately equally resistant to metsulfuron, triasulfuron, and thifensulfuron, and 2.5 times more resistant to tribenuron than thifensulfuron. However, the response of R kochia growing in a spring wheat crop in the field was not consistent with results of the ALS enzyme assays. In field experiments, thifensulfuron at 32 g ai ha−1had little effect on R kochia. In contrast, metsulfuron, triasulfuron, and tribenuron at 8 g ha−1did not reduce R kochia seedling densities, but caused severe stunting such that 2 mo after treatment the shoot biomass of plants in untreated plots was four times greater than in sprayed plots. Herbicides with alternative modes of action including fluroxypyr, bromoxynil/MCPA ester, dichlorprop/2,4-D ester, and 2,4-D ester provided good control of R kochia in the field. Quinclorac did not reduce kochia densities, but surviving plants were stunted. To delay or avoid development of ALS inhibitor-resistant kochia populations, these alternative herbicides applied alone or in tank mixtures could be incorporated into a herbicide rotation.
Improving Johnsongrass (Sorghum halepense) Control in Soybean and Sunflower Cropping Systems
Authors: Van Esso Miguel L. , Ghersa Claudio M.
Published: May 2019

Overall efficacy of control practices for Johnsongrass was evaluated in soybean and sunflower cropping systems where timing of cultural and chemical control practices was adjusted to weed phenological stages by using visually estimated indices (stems 15 to 30 cm in height with 4 to 8 leaves) and with a thermal calendar model to forecast the crucial period for Johnsongrass propagation (when the population's rhizome mass is at a minimum). When visually estimated indices were used, weed infestation at the end of one growing season remained constant for the soybean cropping system and was reduced by about 70% in the sunflower crop. With the thermal calendar, weed infestation was reduced in both cropping systems by more than 90% in one growing season, and Johnsongrass was eradicated in two growing seasons. Although timing the control procedures to the crucial period severely hampered persistence of the weed in both cropping systems, the crop yield of sunflower was reduced by 35%. This yield reduction was caused by the delay in sowing date needed in order to adjust control procedures to the crucial period for propagation.
Effect of Straw, Ash, and Tillage on Dissipation of Imazaquin and Imazethapyr
Authors: Monks C. Dale , Banks Philip A.
Published: May 2019

Experiments were conducted on a Cedarbluff silt loam and a Cecil sandy loam to determine dissipation of imazaquin and imazethapyr as influenced by burning small-grain straw and tillage prior to soybean planting. Corn bioassay detection limits for imazaquin and imazethapyr in the Cedarbluff silt loam were 2.5 to 30 and 5 to 40 ppbw, respectively. Bioassay detection limits for imazaquin and imazethapyr in the Cecil sandy loam were 2.5 to 20 and 10 to 40 ppbw, respectively. Imazaquin and imazethapyr activity was not detectable in soil by 110 to 152 d after treatment. Imazethapyr dissipation was not affected by burning or tillage in the Cedarbluff silt loam and dissipated more slowly in 1989 than imazaquin. Imazaquin dissipation in the Cedarbluff silt loam in 1988 was slower in burned plots than in nonburned plots but was not affected by burning in 1989. No differences were observed between imazaquin and imazethapyr dissipation in the Cecil sandy loam and neither burning or tillage influenced their rate of dissipation in either year. No-till-planted cotton was injured at both locations by imazaquin and imazethapyr that had been applied the previous year.
Persistence of Preemergence Applications of Chlorsulfuron, Metsulfuron, Triasulfuron, and Tribenuron in Three Soils in Greece
Authors: Kotoula-Syka Eleni , Eleftherohorinos Ilias G. , Gagianas Athanasios A. , Sficas Achilleas G.
Published: May 2019

A pot bioassay, based on root growth of pregerminated corn, was used to evaluate factors influencing field persistence of chlorsulfuron, metsulfuron, triasulfuron, and tribenuron, which were applied preemergence at 0, 10, 20, and 40 g ai ha−1to wheat grown in three soils that differed in texture (sandy loam, sandy clay loam, and silty clay loam) and pH (7.9, 4.7, and 7.6). Residual activity and leaching of all herbicides in all soils increased with increasing rate of application, with the exception of tribenuron which showed practically no residual activity and leaching in sandy clay loam soil. Sunflower sown 4 mo after tribenuron application in all soils was not injured by any rate used but was significantly affected by the other herbicides. Lentil and sugarbeet also were affected by all herbicides in all soils. These three crops sown 8 mo after herbicide application were not affected by any herbicide used in the sandy clay loam soil but were injured by chlorsulfuron, triasulfuron, and metsulfuron in the sandy loam soil. Only lentil and sugarbeet were injured by chlorsulfuron in the silty clay loam soil.
Insecticides Do Not Affect Cotton (Gossypium hirsutum) Response to Imazaquin and Imazethapyr
Authors: York Alan C. , Wilcut John W.
Published: May 2019

Field and greenhouse experiments evaluated interactions of soil-applied insecticides and imazaquin and imazethapyr on growth and development of cotton. Imazaquin and imazethapyr were applied PPI at 0 to 6 and 0 to 16 g ae ha−1, respectively, in the greenhouse (plus a no-insecticide control), and 0 to 72 g ha−1in the field in combination with aldicarb, disulfoton, and phorate (without a no-insecticide control) applied in the seed furrow. Cotton shoot fresh weight in the greenhouse experiment decreased linearly as herbicide rates increased. Greater reductions in shoot fresh weight were noted with imazaquin than with imazethapyr. Compared with no insecticide, the methylcarbamate insecticide aldicarb and the organophosphate insecticides disulfoton and phorate did not affect cotton response to either herbicide. In the field, cotton injury increased while stand, yield, and maturity decreased as herbicide rates increased. Delayed maturity was due to a lower percentage of bolls produced on sympodia from main stem nodes four to nine. Imazaquin caused greater injury, greater reductions in stand, greater delays in maturity, and lower yields than did imazethapyr. Earlier maturity was noted with aldicarb-treated cotton. Compared with aldicarb, disulfoton and phorate did not alter cotton response to imazaquin or imazethapyr.
Vernal Seedling Emergence Model for Common Lambsquarters (Chenopodium album)
Authors: Harvey Stephen J. , Forcella Frank
Published: May 2019

Knowledge of timing and extent of weed emergence before and immediately after crop seedbed preparation is needed to decrease need for preplant herbicides and increase efficacy of postemergence weed control in crops with either mechanical or chemical methods. Such knowledge is important for weeds that infest most crops over a wide area. For these reasons a mechanistic seedling emergence model based solely on soil temperature was developed for common lambsquarters. The model was validated using four sets of field data collected in 1988, 1990, and 1991 near Morris, MN. Agreement of predicted and observed emergence values across all site-years was 0.95 and the coefficient of determination (R2) was 0.98 (P < 0.001). Agreement for individual site-years was 0.96, 1.08, 1.08, and 0.98 and associated R2values were 0.99, 0.99, 0.99, and 0.98 (P < 0.001 for each site-year), indicating close agreement between predicted and actual emergence values.
Effect of Corn-Induced Shading on Dry Matter Accumulation, Distribution, and Architecture of Redroot Pigweed (Amaranthus retroflexus)
Authors: Mclachlan Stephane M. , Tollenaar Matthijs , Swanton Clarence J. , Weise Stephan F.
Published: May 2019

A fundamental component of modeling crop interference is the effect of understory photosynthetic photon flux density (PPFD) on weed architecture and growth. The effect of decreased PPFD on spaced redroot pigweed dry matter accumulation, distribution, and plant architecture was quantified by increasing corn density and delaying weed planting date. As canopy-transmitted PPFD declined, total dry matter accumulation decreased and relative dry matter distribution was greater to main-stem components than to branch components. Increased rectangularity in understory weed architecture was associated with a concomitant decrease in branch number. The proportion of leaf area and dry matter in the upper segment of the redroot pigweed increased as PPFD declined with increased corn density. Results suggest that changes in plant architecture, as influenced by canopy-transmitted PPFD, may be as important as those of total dry matter and leaf area when describing and predicting the effects of crop-weed interference.
Germination, Emergence, and Seedling Establishment of Buffalo Gourd (Cucurbita foetidissima)
Authors: Horak Michael J. , Sweat Jonathan K.
Published: May 2019

Studies were conducted to determine the effects of scarification, temperature, osmotic potential, and pH on seed germination of buffalo gourd and to examine seedling emergence and establishment. Mechanical and chemical scarification did not increase germination compared to non-scarified seed. Seed germinated at constant temperatures in the dark from 15 to 37 C with optimum germination at 25 C. As osmotic potentials became more negative from −0.1 to −0.8 MPa, germination decreased from 77 to 53%. Germination increased from 15% at pH 2.2 to 90% at pH 8. Seedlings were able to emerge from depths as great as 12 cm, and plants younger than 19 d were not able to sprout from the roots when the shoots were removed.
Germination of Previously Buried Seeds of Fringed Sage (Artemisia frigida)
Authors: Bai Yuguang , Romo J. T.
Published: May 2019

Seeds of fringed sage were collected in four different years in the Northern Mixed Prairie and placed in sealed vials in the field for up to 5 yr. The seeds were exhumed monthly and incubated at 10 or 20 C in light or darkness. Germination was greater at 10 than 20 C and greater in light than darkness. The overriding influences of light and temperature generally decreased as seeds aged. No well-defined dormancy/nondormancy or conditional dormancy/nondormancy cycles were revealed. Longevity of seeds varied among collections, ranging from 3½ to more than 5 yr. Patterns in germination of different collections were similar when they experienced the same annual changes in temperatures, indicating that germination of previously buried seeds of fringed sage was regulated by temperature. This regulating effect varied among years of storage; germination either increased or decreased with increasing temperatures, or was not affected. Results suggest that fringed sage seeds can germinate and emerge anytime during the growing season if temperature and moisture conditions are suitable. Continuous germination may enable fringed sage to occupy safe sites as they develop over time.
Cross-Resistance of Several Diclofop-Resistant Wild Oat (Avena fatua) Biotypes From the Willamette Valley of Oregon
Authors: Seefeldt Steven S. , Gealy David R. , Brewster Bill D. , Fuerst E. Patrick
Published: May 2019

The first occurrences of wild oat resistance to diclofop in the Willamette Valley of Oregon were reported in 1990. Among eight resistant biotypes, GR50values for diclofop were 3 to 64 times greater than the GR50for a susceptible wild oat biotype. GR50values for other aryloxyphenoxypropionate herbicides varied from 1 to over 100 times greater than a susceptible biotype. Only one resistant biotype was resistant to cyclohexanedione herbicides, and this was only a three-fold increase in GR50. Except for one biotype that had a low level of resistance to pronamide, none of the wild oat biotypes were cross-resistant to any other commonly used wild oat herbicide. Levels of resistance and cross-resistance did not follow a consistent pattern among biotypes in this study, suggesting more than one resistance trait. There were significant differences in the light use efficiency, height, dry weight, leaf area, and extent and timing of tillering and flowering of four wild oat biotypes studied. These physiological and morphological differences suggest that these resistant biotypes were selected independently. The diversity of resistance patterns and the coevolution of resistance at several locations will add to the difficulty of resistance management