Production costs in many shale-gas plays exceed current gas prices, and maintaining production requires ever-increasing drilling and the capital input to support it. SHALE GAS Two technologies - ...horizontal drilling coupled with large-scale, multi-stage hydraulic fracturing (fracking) - have made it possible to extract hydrocarbons trapped in impermeable rocks (see Nature 477, 271-275; 2011). Existing production histories are a few years at best, and thus are insufficient to substantiate such long lifetimes for wells. Because production declines more steeply than these models typically suggest, the method often overestimates ultimate recoveries and economic performance (see go.nature.com/kiamlk).
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Leadership is a key predictor of employee, team, and organizational creativity and innovation. Research in this area holds great promise for the development of intriguing theory and impactful policy ...implications, but only if empirical studies are conducted rigorously. In the current paper, we report a comprehensive review of a large number of empirical studies (N = 195) exploring leadership and workplace creativity and innovation. Using this article cache, we conducted a number of systematic analyses and built narrative arguments documenting observed trends in five areas. First, we review and offer improved definitions of creativity and innovation. Second, we conduct a systematic review of the main effects of leadership upon creativity and innovation and the variables assumed to moderate these effects. Third, we conduct a systematic review of mediating variables. Fourth, we examine whether the study designs commonly employed are suitable to estimate the causal models central to the field. Fifth, we conduct a critical review of the creativity and innovation measures used, noting that most are sub-optimal. Within these sections, we present a number of taxonomies that organize extant research, highlight understudied areas, and serve as a guide for future variable selection. We conclude by highlighting key suggestions for future research that we hope will reorient the field and improve the rigour of future research such that we can build more reliable and useful theories and policy recommendations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We report a systematic and critical review of abusive supervision research to provide a comprehensive catalogue of the correlates of abusive supervision (i.e., antecedents, outcomes, mediators, and ...moderators) and identify four major challenges facing the field. First, abusive supervision is conceptualized in a confused manner that conflates followers’ subjective evaluations of abuse with leaders’ behaviors. Second, we consider how conceptual confusion is reflected in and undermines dominant measurement tools. Third, we identify and critique overreliance on cross-sectional survey-based studies and vignette experiments, which vary considerably in the extent to which they can evidence causal effects. Fourth, we consider the fact that abusive supervision is a low base rate phenomenon (i.e., is rarely reported). Using novel and simulated data we demonstrate that most past research is ill-equipped to make claims about the effects of intermediate or high levels of abusive supervision. Throughout, we explain how each challenge limits past research and offer achievable recommendations for a fundamental rethink of abusive supervision. In the discussion, we synthesize the recommendations for rethinking the conceptualization, measurement, and empirical study of abusive supervision. Only by overcoming these challenges will future research be robust enough to provide meaningful theoretical advances and useful policy implications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
5.
Turbulence in the TW Hya Disk Flaherty, Kevin M.; Hughes, A. Meredith; Teague, Richard ...
The Astrophysical journal,
04/2018, Volume:
856, Issue:
2
Journal Article
Peer reviewed
Open access
Turbulence is a fundamental parameter in models of grain growth during the early stages of planet formation. As such, observational constraints on its magnitude are crucial. Here we self-consistently ...analyze ALMA CO(2-1), SMA CO(3-2), and SMA CO(6-5) observations of the disk around TW Hya and find an upper limit on the turbulent broadening of <0.08cs ( < 0.007 for defined only within 2-3 pressure scale heights above the midplane), lower than the tentative detection previously found from an analysis of the CO(2-1) data. We examine in detail the challenges of image plane fitting versus directly fitting the visibilities, while also considering the role of the vertical temperature gradient, systematic uncertainty in the amplitude calibration, and assumptions about the CO abundance, as potential sources of the discrepancy in the turbulence measurements. These tests result in variations of the turbulence limit between <0.04cs and <0.13cs, consistently lower than the 0.2-0.4cs found previously. Having ruled out numerous factors, we restrict the source of the discrepancy to our assumed coupling between temperature and density through hydrostatic equilibrium in the presence of a vertical temperature gradient and/or the confinement of CO to a thin molecular layer above the midplane, although further work is needed to quantify the influence of these prescriptions. Assumptions about hydrostatic equilibrium and the CO distribution are physically motivated, and may have a small influence on measuring the kinematics of the gas, but they become important when constraining small effects such as the strength of the turbulence within a protoplanetary disk.
Purpose
To assess the diagnostic accuracy of magnetic resonance imaging (MRI) perfusion against perfusion single photon emission tomography (SPECT) screening for chronic thromboembolic pulmonary ...hypertension (CTEPH). Ventilation/perfusion (V/Q) scintigraphy is recommended to screen for suspected CTEPH. It has previously been shown that 3D dynamic contrast‐enhanced (DCE) lung perfusion MRI has a similar sensitivity for diagnosing CTEPH in comparison to planar perfusion scintigraphy; however, planar scintigraphy has now been largely replaced by SPECT, due to higher spatial resolution and sensitivity.
Materials and Methods
Consecutive patients with suspected CTEPH or unexplained pulmonary hypertension attending a referral center, who underwent lung DCE perfusion MRI at 1.5T, perfusion SPECT, and computed tomography pulmonary angiography (CTPA) within 14 days of right heart catheterization, from April 2013 to April 2014, were included. DCE‐MR, SPECT, and CTPA were independently analyzed by two blinded radiologists. Disagreements were corrected by consensus. The gold standard reference for the diagnosis of chronic thromboemboli was based on a review of multimodality imaging and clinical findings.
Results
In all, 74 patients with suspected CTEPH underwent all three modalities. Forty‐six were diagnosed with CTEPH (36) or chronic thromboembolic disease (CTED) (10). 3D DCE perfusion MRI correctly identified all patients (sensitivity of 100%), compared with a 97% sensitivity for SPECT.
Conclusion
DCE lung perfusion MRI has increased sensitivity when compared with perfusion scintigraphy in screening for CTEPH. As MRI does not use ionizing radiation, it should be considered as a first‐line imaging modality in suspected CTEPH.
Level of Evidence: 3
Technical Efficacy: Stage 3
J. Magn. Reson. Imaging 2017;46:1693–1697.
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The metalloid arsenic is a natural environmental contaminant to which humans are routinely exposed in food, water, air, and soil. Arsenic has a long history of use as a homicidal agent, but in the ...past 100 years arsenic, has been used as a pesticide, a chemotherapeutic agent and a constituent of consumer products. In some areas of the world, high levels of arsenic are naturally present in drinking water and are a toxicological concern. There are several structural forms and oxidation states of arsenic because it forms alloys with metals and covalent bonds with hydrogen, oxygen, carbon, and other elements. Environmentally relevant forms of arsenic are inorganic and organic existing in the trivalent or pentavalent state. Metabolism of arsenic, catalyzed by arsenic (+3 oxidation state) methyltransferase, is a sequential process of reduction from pentavalency to trivalency followed by oxidative methylation back to pentavalency. Trivalent arsenic is generally more toxicologically potent than pentavalent arsenic. Acute effects of arsenic range from gastrointestinal distress to death. Depending on the dose, chronic arsenic exposure may affect several major organ systems. A major concern of ingested arsenic is cancer, primarily of skin, bladder, and lung. The mode of action of arsenic for its disease endpoints is currently under study. Two key areas are the interaction of trivalent arsenicals with sulfur in proteins and the ability of arsenic to generate oxidative stress. With advances in technology and the recent development of animal models for arsenic carcinogenicity, understanding of the toxicology of arsenic will continue to improve.
We introduce the Disk Substructures at High Angular Resolution Project (DSHARP), one of the initial Large Programs conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The primary ...goal of DSHARP is to find and characterize substructures in the spatial distributions of solid particles for a sample of 20 nearby protoplanetary disks, using very high resolution (∼0 035, or 5 au, FWHM) observations of their 240 GHz (1.25 mm) continuum emission. These data provide a first homogeneous look at the small-scale features in disks that are directly relevant to the planet formation process, quantifying their prevalence, morphologies, spatial scales, spacings, symmetry, and amplitudes, for targets with a variety of disk and stellar host properties. We find that these substructures are ubiquitous in this sample of large, bright disks. They are most frequently manifested as concentric, narrow emission rings and depleted gaps, although large-scale spiral patterns and small arc-shaped azimuthal asymmetries are also present in some cases. These substructures are found at a wide range of disk radii (from a few astronomical units to more than 100 au), are usually compact ( 10 au), and show a wide range of amplitudes (brightness contrasts). Here we discuss the motivation for the project, describe the survey design and the sample properties, detail the observations and data calibration, highlight some basic results, and provide a general overview of the key conclusions that are presented in more detail in a series of accompanying articles. The DSHARP data-including visibilities, images, calibration scripts, and more-are released for community use at https://almascience.org/alma-data/lp/DSHARP.
Marine phytoplankton, and in particular diatoms, are responsible for almost half of all primary production on Earth. Diatom species thrive from polar to tropical waters and across light environments ...that are highly complex to relatively benign, and so have evolved highly divergent strategies for regulating light capture and utilization. It is increasingly well established that diatoms have achieved such successful ecosystem dominance by regulating excitation energy available for generating photosynthetic energy via highly flexible light harvesting strategies. However, how different light harvesting strategies and downstream pathways for oxygen production and consumption interact to balance excitation pressure remains unknown. We therefore examined the responses of three diatom taxa adapted to inherently different light climates (estuarine Thalassioisira weissflogii, coastal Thalassiosira pseudonana and oceanic Thalassiosira oceanica) during transient shifts from a moderate to high growth irradiance (85 to 1200 μmol photons m-2 s-1). Transient high light exposure caused T. weissflogii to rapidly downregulate PSII with substantial nonphotochemical quenching, protecting PSII from inactivation or damage, and obviating the need for induction of O2 consuming (light-dependent respiration, LDR) pathways. In contrast, T. oceanica retained high excitation pressure on PSII, but with little change in RCII photochemical turnover, thereby requiring moderate repair activity and greater reliance on LDR. T. pseudonana exhibited an intermediate response compared to the other two diatom species, exhibiting some downregulation and inactivation of PSII, but high repair of PSII and induction of reversible PSII nonphotochemical quenching, with some LDR. Together, these data demonstrate a range of strategies for balancing light harvesting and utilization across diatom species, which reflect their adaptation to sustain photosynthesis under environments with inherently different light regimes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Streptococcus gallolyticus subspecies gallolyticus
(SGG) and
Fusobacterium (F.) nucleatum
have been implicated in colorectal carcinogenesis. Here, the association of immune responses to ...bacterial exposure with advancing stages of colorectal neoplasia was assessed by multiplex serology.
Methods
Immunoglobulin (Ig) A and G antibody responses to eleven proteins each of
F. nucleatum
and SGG were measured in plasma of controls (
n
= 100) and patients with colorectal cancer (CRC,
n
= 25), advanced adenoma (
n
= 82), or small polyps (
n
= 85). Multivariable logistic regression was used to evaluate the association of bacterial sero-positivity with colorectal neoplasia. In a cohort subset with matched data (
n
= 45),
F. nucleatum
sero-positivity was correlated with bacterial abundance in both neoplastic and matched normal tissue.
Results
IgG sero-positivity to Fn1426 of
F. nucleatum
was associated with an increased CRC risk (OR = 4.84; 95% CI 1.46–16.0), while IgA sero-positivity to any SGG protein or specifically Gallo0272 and Gallo1675 alone was associated with increased advanced adenoma occurrence (OR = 2.02, 95% CI 1.10–3.71; OR = 2.67, 95% CI 1.10–6.46; and OR = 6.17, 95% CI 1.61–23.5, respectively). Only
F. nucleatum
abundance in the normal mucosa positively correlated with the IgA response to the Fn1426 antigen (Correlation coefficient (r) = 0.38,
p
< 0.01).
Conclusion
Antibody responses to SGG and
F. nucleatum
were associated with occurrence of colorectal adenomas and CRC, respectively. Further studies are needed to clarify the role these microbes or the immune response to their antigens may have in colorectal carcinogenesis stages.
Graphical Abstract
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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