bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms and stereoselectivities of phosphine‐catalyzed (3+3) cycloaddition reaction between azomethine imine and ynone: A computational study
Authors: Li Yan , Fu Wenwen , Tian Ruixue , Liang Changhai 
Published: September 2018

AbstractTo understand the mechanisms and origins of stereoselectivities in PPh
3‐catalyzed (3 + 3) cycloaddition reaction of but‐3‐yn‐2‐one with azomethine imine, density functional theory (DFT) and ReaxFF molecular dynamics (MD) simulations have been conducted. Various possible reaction pathways have been examined. DFT calculations indicate that this reaction is initiated by nucleophilic attack of catalyst PPh
3 to but‐3‐yn‐2‐one to form intermediate 1, followed by proton transfer leads to intermediate 2. The subsequent nucleophilic addition of 2 to azomethine imine forms intermediate 3. Then, intermediate 3 undergoes intramolecular cycloaddition, 1,2‐proton transfer, and elimination of catalyst affording the final product. A trace amount of PhOH plays an important role in the proton transfer process. For the stereoselectivity determining CC bond formation step, both DFT calculations and MD simulations demonstrate that the R‐configured P(R) is the predominant product. Furthermore, high Z/E‐selectivity is predicted for the studied reaction. Our computational results are in good agreement with previous experimental observations. The present study should be useful to the development of this kind reaction in the future.
Superacidity of P(OH)3 and SO(OH)2 derivatives of cyclopentadiene and vinylcyclopentadiene in the gas phase: A computational DFT analysis
Authors: Valadbeigi Younes , Vianello Robert 
Published: September 2018

AbstractStrong Brønsted acids were designed using a simple strategy of replacing double‐bonded oxygen atoms in mineral acids H3PO4 and H2SO4 with cyclopentadiene and vinylcyclopentadiene moieties, followed by a substitution with strong electron‐withdrawing cyano groups. Their intrinsic gas‐phase acidity was assessed by the B3LYP density functional theory calculations employing the 6‐311++G(d,p) basis set, and many highly potent superacids were identified. The pronounced acidity of these conjugates is due to two predominant factors, namely, (i) an increase in the aromaticity of the five‐membered ring on deprotonation, as evaluated through the NICS parameters, and (ii) an extension of the conjugated π‐network enabled by the cyano groups that efficiently distribute an excess negative charge over a large number of atoms in conjugate bases. The SO(OH)2 derivatives are generally more acidic than the corresponding P(OH)3 counterparts so that the ΔHacid values for the SO(OH)2 and P(OH)3 derivatives with CN substituents evaluated here are 260‐266 and 263‐272 kcal mol−1, respectively. Given the growing interest in highly acidic molecules together with related acidic catalysts and metal complexing agents, the results presented here should direct the attention toward utilizing proposed systems as improved organic materials, and their synthesis is highly recommended.
Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona
Authors: Hadley Daniel R. , Grams Paul E. , Kaplinski Matthew A. 
Published: September 2018

AbstractSandbars along the Colorado River in Grand Canyon National Park, USA, are an important recreational resource used as campsites by over 25,000 river runners and hikers annually. The number and size of campsites decreased following the completion of Glen Canyon Dam in 1963 due to reductions of sediment that replenish sandbars and increases in vegetation cover caused by flow regulation. Campsite area continues to decrease despite the use of controlled floods to rebuild sandbars. We quantify the relative magnitude of factors that contribute to changes in campsite size, such as fluvial deposition and erosion, gullying, and vegetation expansion with analysis of four‐band aerial imagery and digital elevation models. Campsite area declined by 37% between 2002 and 2016 (an average of 161 m2 per site at long‐term monitoring sites). Two drivers contributed to campsite area change: (a) short‐term gains and losses associated with controlled floods and flood‐deposit erosion and (b) long‐term one‐directional loss of campsite area caused by vegetation encroachment. There was more erosion and slope change at sites in critical reaches—sections of river where campsites are infrequent or in high demand—than in noncritical reaches. Vegetation continues to expand at campsites under flow regulation, particularly in noncritical reaches. Although controlled floods have contributed to short‐term increases in sandbar size, long‐term increases in campsite area have not occurred because of sandbar erosion between controlled floods and vegetation expansion. Manual vegetation removal may need to be considered in future management strategies.
High‐temperature 2D Fermi surface of SrTiO3 studied by energy‐filtered PEEM
Authors: Mathieu Claire , Gonzalez Sara , Lubin Christophe , Copie Olivier , Feyer Vitaliy , Schneider Claus M. , Barrett Nick 
Published: September 2018

Functional oxides displaying phenomena such as 2D electron gas (2DEG) at oxide interfaces represent potential technological breakthroughs for post‐CMOS (Complementary Metal Oxide Semiconductor) electronics. Noninvasive techniques are required to study the surface chemistry and electronic structure underlying their often unique electrical properties. The sensitivity of photoemission electron microscopy (PEEM) to local potential, chemistry, and electronic structure makes it an invaluable tool for probing the near surface region of microscopic regions and domains of functional materials. In particular, PEEM allows single shot acquisition of the 2D Fermi surface and full angular probing of the symmetry‐induced intensity modulations. We present results demonstrating a 2DEG at the surface of SrTiO3(001) at 140 K. The 2DEG is created by soft X‐ray irradiation and can be reversibly controlled by a combination of soft X‐rays and oxygen partial pressure.
How government oversight adds time to contractor engineering work
Authors: Brainard Samantha M. , Szajnfarber Zoe 
Published: September 2018

AbstractOversight is necessary for evaluating the performance of contractors building complex systems for the U.S. government, but it can also result in additional program costs. In order to accurately measure the extent of these additional costs, stakeholders need to understand how oversight‐required activities add time to work. To that end, this paper presents the data from a qualitative research study to investigate how oversight adds time to contractor engineering work at a major U.S. aerospace company. We observed that oversight activities require many tasks to complete, which can add cascades of new activities that are performed in multiple iterations. Oversight activities cannot be accounted for in a binary way—oversight adds time to parts of all activities that the contractor performs. We describe the mechanisms through which oversight impacts work by extending the time spent on all activities. Understanding how added time occurs could help both contractors and government program managers determine ways to reduce unnecessary costs. Implications of these findings for systems engineers interested in conducting studies to measure the impact of oversight are discussed.
Irrigated farming systems: using the water footprint as an indicator of environmental, social and economic sustainability
Authors: Altobelli F. , Cimino O. , Natali F. , Orlandini S. , Gitz V. , Meybeck A. , Dalla Marta A. 
Published: September 2018

AbstractIn the current study, for the main crops cultivated in the Campania region (South of Italy), three indicators were proposed and analysed. The blue water footprint (WFb), which gives an indication of the impact of irrigation on the water resource; the gross margin WFb (GMWFb), describing the economic productivity of irrigation; and the job WFb (JWFb) that expresses the social value of blue water in terms of job opportunities. Results confirmed that water applied through irrigation is much higher compared with crop requirements. In terms of GMWFb, silage maize, maize and alfalfa had the highest values, while olive, potato and tomato had the lowest. Concerning JWFb, silage maize was the crop with the highest value. Even though a deeper analysis should be done in terms of added value in the entire supply chain, the results indicated a clear difference between the crops related to animal feeding (alfalfa, maize) and the other crops taken into consideration. In fact, for the former, both the GMWFb and the JWFb achieved their highest values. Results showed that for certain irrigation volumes and for certain crops, the economic and social impacts are very different and the choice of an irrigated crop rather than another has different repercussions in terms of environmental and socio-economic sustainability. The proposed indicators would allow water managers and farmers to assess and compare production systems in terms of the different benefits that their use of water can provide.
Sustainable wildlife extraction and the impacts of socio-economic change among the Kukama-Kukamilla people of the Pacaya-Samiria National Reserve, Peru
Authors: Kirkland Maire , Eisenberg Cristina , Bicerra Andy , Bodmer Richard E. , Mayor Pedro , Axmacher Jan C. 
Published: September 2018

AbstractThroughout the tropics, hunting and fishing are critical livelihood activities for many Indigenous peoples. However, these practices may not be sustainable following recent socio-economic changes in Indigenous populations. To understand how human population growth and increased market integration affect hunting and fishing patterns, we conducted semi-structured interviews in five Kukama-Kukamilla communities living along the boundary of the Pacaya-Samiria National Reserve, in the Peruvian Amazon. Extrapolated annual harvest rates of fish and game species by these communities amounted to 1,740 t and 4,275 individuals (67 t), respectively. At least 23 fish and 27 game species were harvested. We found a positive correlation between village size and annual community-level harvest rates of fish and a negative relationship between market exposure and mean per-capita harvest rates of fish. Catch-per-unit-effort (CPUE) analyses indicated local depletion of fish populations around larger, more commercial communities. Catch-per-unit-effort of fish was lower in more commercial communities and fishers from the largest village travelled further into the Reserve, where CPUE was higher. We found no effect of village size or market exposure on harvest rates or CPUE of game species. However, larger, more commercial communities targeted larger, economically valuable species. This study provides evidence that human population growth and market-driven hunting and fishing pose a growing threat to wildlife and Indigenous livelihoods through increased harvest rates and selective harvesting of species vulnerable to exploitation.
High susceptibility of the laboratory-reared biting midges Culicoides nubeculosus to Haemoproteus infections, with review on Culicoides species that transmit avian haemoproteids
Authors: Bukauskaitė Dovilė , Iezhova Tatjana A. , Ilgūnas Mikas , Valkiūnas Gediminas 
Published: September 2018

AbstractHaemosporidian parasites belonging to Haemoproteus cause avian diseases, however, vectors remain unidentified for the majority of described species. We used the laboratory-reared biting midges Culicoides nubeculosus to determine if the sporogonic development of three widespread Haemoproteus parasites completes in this insect. The midges were reared and fed on one common blackbird, white wagtail and thrush nightingale naturally infected with Haemoproteus minutus, Haemoproteus motacillae and Haemoproteus attenuatus, respectively. The engorged females were dissected in order to follow their sporogonic development. Microscopic examination was used to identify sporogonic stages. Bayesian phylogeny based on partial cytochrome b gene was constructed in order to determine phylogenetic relationships among Culicoides species-transmitted haemoproteids. All three parasites completed sporogony. Phylogenetic analysis placed Culicoides species transmitted haemoproteids in one well-supported clade, proving that such analysis readily indicates groups of dipteran insects transmitting avian haemoproteids. Available data show that 11 species of Culicoides have been proved to support complete sporogony of 18 species of avian haemoproteids. The majority of Culicoides species can act as vectors for many Haemoproteus parasites, indicating the low specificity of these parasites to biting midges, whose are globally distributed. This calls for control of haemoproteid infections during geographical translocation of infected birds.
Ethnic minority position and migrant status as risk factors for psychotic symptoms in the general population: a meta-analysis
Authors: Leaune Edouard , Dealberto Marie-Jose , Luck David , Grot Stéphanie , Zeroug-Vial Halima , Poulet Emmanuel , Brunelin Jerome 
Published: September 2018

AbstractPsychotic symptoms (PS) are experienced by a substantial proportion of the general population. When not reaching a threshold of clinical relevance, these symptoms are defined as psychotic experiences (PEs) and may exist on a continuum with psychotic disorders. Unfavorable socio-environmental conditions, such as ethnic minority position (EMP) and migrant status (MS), may increase the risk of developing PS and PEs. We conducted an electronic systematic review and a meta-analysis assessing the role of EMP and MS for the development and persistence of PS in the general population. Sub-group analyses were performed investigating the influence of ethnic groups, host countries, age, types of PS, and scales. Twenty-four studies met our inclusion criteria. EMP was a relevant risk factor for reporting PS [odds ratio (OR) 1.44, 95% confidence interval (CI) 1.22–1.70) and PEs (OR 1.36, 95% CI 1.16–1.60). The greatest risk was observed in people from the Maghreb and the Middle East ethnic groups in Europe (OR 3.30, 95% CI 2.09–5.21), in Hispanic in the USA (OR 1.98, 95% CI 1.43–2.73), and in the Black populations (OR 1.85, 95% CI 1.39–2.47). We found a significant association between MS and delusional symptoms (OR 1.47, 95% CI 1.33–1.62). We found no association between EMP and persistence of PEs.EMP was associated with increased risk of reporting PS and PEs, and the risk was higher in ethnic groups facing deprivation and discrimination. We found an association between MS and delusional symptoms. These results raise questions about the precise role of socio-environmental factors along the psychosis continuum.
Can brief alcohol interventions in general hospital inpatients improve mental and general health over 2 years? Results from a randomized controlled trial
Authors: Freyer-Adam Jennis , Baumann Sophie , Haberecht Katja , Bischof Gallus , Meyer Christian , Rumpf Hans-Jürgen , John Ulrich , Gaertner Beate 
Published: September 2018

AbstractBackgroundLittle is known about the impact of brief alcohol interventions on mental and general health. The aim was to investigate whether brief interventions for general hospital inpatients with at-risk drinking can improve mental and general health over 2 years; and whether effects are dependent on how they are delivered: in-person or through computer-generated feedback letters (CO).MethodsThree-arm randomized controlled trial with 6-, 12-, 18-, and 24-month follow-ups. Data were collected on 13 general hospital wards from four medical departments (internal medicine, surgical medicine, trauma surgery, and ear-nose-throat) of one university hospital in northeastern rural Germany. A consecutive sample of 961 18- to 64-year-old general hospital inpatients with at-risk alcohol use was recruited through systematic screening. Inpatients with particularly severe alcohol problems were excluded. Participants were allocated to: in-person counseling (PE), CO, and assessment only (AO). PE and CO included three contacts: on the ward, 1, and 3 months later. Mental and general health were assessed using the five-item mental health inventory (0–100) and a one-item general health measure (0, poor – 4, excellent).ResultsLatent growth models including all participants revealed: after 24 months and in contrast to AO, mental and general health were improved in PE (change in mean difference, ΔMmental = 5.13, p = 0.002, Cohen's d = 0.51; ΔMgeneral = 0.20, p = 0.005, d = 0.71) and CO (ΔMmental = 6.98, p < 0.001, d = 0.69; ΔMgeneral = 0.24, p = 0.001, d = 0.86). PE and CO did not differ significantly.ConclusionsBeyond drinking reduction, PE and CO can improve general hospital inpatients’ self-reported mental and general health over 2 years.
THE AVANT GARDE AS EXFORM
Authors: Redhead Lauren 
Published: September 2018

AbstractPeter Bürger's critique of the historical avant garde (in Theory of the Avant Garde) accounts for its ineffectual nature as a political movement because of its relationship with institutions. He argues for hermeneutics to be employed as a critique of ideology, and as a facet of the understanding of the ‘historicity of aesthetic categories’. The influence of institutions on music since 1968 has served as a central part of its critique: the work concept itself seems to enshrine political ineffectiveness and the bourgeois nature of art practice that ought to be critiqued by an avant garde. In contrast, Nicolas Bourriaud's concept of the ‘exform’ re-conceives the avant garde as outside of institutions and an idea of ‘progress’ that is aligned with a dominant capitalist ideology. He frames the task of the avant-garde artist as giving energy to ‘waste’, outside of political and ideological institutions. This type of avant-garde practice functions to ‘bring precarity to mind: to keep the notion alive that intervention in the world is possible’. This article explores the exform with respect to the work of the British composer Chris Newman and the Swiss composer Annette Schmucki, and considers how Bourriaud's approach to re-thinking the avant garde might apply specifically to contemporary and experimental music in the present.
Modeling the chemistry in the icy mantles of interstellar grains
Authors: Kalvāns Juris 
Published: September 2018

AbstractThe diffusion and photoprocessing of molecules within interstellar ices has been verified experimentally but often not fully included in astrochemical models. With models that consider photodissociation, binary reactions, and diffusion for molecules on the surface and in bulk ice, we explored the chemistry of interstellar and circumstellar ices in gravitationally contracting low-mass starless and prestellar cores, and a protostellar envelope.Results. Photoprocessing gradually converts mixed H2O and CO ices into CO2 and allows for a late synthesis of icy organic species. Different layers within a single icy mantle favor the synthesis different species. Deuterium-rich molecules are concentrated on the outer surface of ice. Formation of organic molecules in bulk ice lowers their average deuterium content. The abundances of major icy species can be changed by about 25-50 % because of ice photoprocessing. Inter-layer diffusion of icy species allows sequential evaporation in protostellar envelopes, which occurs over a prolonged period.
High-Temperature Chemistry in External Galaxies
Authors: Harada Nanase 
Published: September 2018

AbstractIn external galaxies, some galaxies have higher activities of star formation and central supermassive black holes. The interstellar medium in those galaxies can be heated by different mechanisms such as UV-heating, X-ray heating, cosmic-ray heating, and shock/mechanical heating. Chemical compositions can also be affected by those heating mechanisms. Observations of many molecular species in those nearby galaxies are now possible with the high sensitivity of Atacama Large Millimeter/sub-millimeter Array (ALMA). Here I cover different chemical models for those heating mechanisms. In addition, I present recent ALMA results of extragalactic astrochemistry including our results of a face-on galaxy M83 and an infrared-luminous merger NGC 3256.
Imaging the water snowline in protostellar envelopes
Authors: van ’t Hoff Merel L. R. 
Published: September 2018

AbstractDetermining the locations of the major snowlines in protostellar environments is crucial to fully understand the planet formation process and its outcome. Despite being located far enough from the central star to be spatially resolved with ALMA, the CO snowline remains difficult to detect directly in protoplanetary disks. Instead, its location can be derived from N2H+emission, when chemical effects like photodissociation of CO and N2are taken into account. The water snowline is even harder to observe than that for CO, because in disks it is located only a few AU from the protostar, and from the ground only the less abundant isotopologue H218O can be observed. Therefore, using an indirect chemical tracer, as done for CO, may be the best way to locate the water snowline. A good candidate tracer is HCO+, which is expected to be particularly abundant when its main destructor, H2O, is frozen out. Comparison of H218O and H13CO+emission toward the envelope of the Class 0 protostar IRAS2A shows that the emission from both molecules is spatially anticorrelated, providing a proof of concept that H13CO+can indeed be used to trace the water snowline in systems where it cannot be imaged directly.
Unveiling the mid-plane temperature and mass distribution in the giant-planet formation zone
Authors: Zhang Ke , Bergin Edwin A. , Blake Geoffrey A. , Cleeves L. Ilsedore , Schwarz Kamber R. 
Published: September 2018

AbstractCore-accretion theory predicts that the formation of giant planets predominantly occurs at the dense mid-plane of the inner ∼50 AU of protoplanetary disks. However, due to observational limitation, this critical region remains to be the least charted area in protoplanetary disks. With its great sensitivity, ALMA recently started to image optically thin line emissions arisen from the mid-plane of the inner 50AU in nearby disks, which unlocks an exciting new path to directly constrain the physical properties of the giant planet formation zone through gas tracers. Here we present the first spatially resolved observations of the 13C18O J=3-2 line emission in the TW Hya disk. We show that this emission is optically thin even inside the CO mid-plane snowline. Combining it with the C18O J=3-2 images and the previously detected HD J=1-0 flux, we directly constrain the mid-plane temperature and optical depths of the CO gas and dust. We report a mid-plane CO snowline at 20.5 ± 1.3 AU, a mid-plane temperature distribution of 27+4−3×(R/20.5AU)-0.47+0.06−0.07 K, and a gas mass distribution of 13+8−5×(R/20.5AU)-0.9+0.4−0.3 g cm−2 between 5-20.5 AU in the TW Hya protoplanetary disk. We find a total gas/mm-sized dust mass ratio of 140 ± 40 in this region, suggesting that ∼2.4 earth mass of dust aggregates have grown to > cm sizes (and perhaps much larger).