bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of antral follicle count and serum anti‐Müllerian hormone level for determination of gonadotropin dosing in in‐vitro fertilization: randomized trial
Authors: LI H. W. R. , Ko J. K. Y. , Lee V. C. Y. , Yung S. S. F. , Lau E. Y. L. , Yeung W. S. B. , Ho P. C. , Ng E. H. Y.
Published: July 2019

Objective

To compare the proportion of women achieving a desired ovarian response following ovarian stimulation when gonadotropin dosing was determined based on antral follicle count (AFC) vs serum anti‐Müllerian hormone (AMH) level, in women undergoing in‐vitro fertilization (IVF) using the gonadotropin‐releasing hormone (GnRH) antagonist protocol.

Methods

This was a randomized double‐blind trial carried out in a university‐affiliated assisted reproduction unit. A total of 200 women undergoing their first IVF cycle using the GnRH‐antagonist protocol between April 2016 and February 2018 were randomized to determination of gonadotropin dosing based on either AFC or serum AMH level measured in the pretreatment cycle 1 month before the IVF cycle. Patients underwent IVF as per our center's standard protocol. The proportion of subjects achieving a desired ovarian response, defined as retrieval of six to 14 oocytes, was compared between the two study arms. Subgroup analysis of patients with baseline AFC > 5 and those with baseline AFC ≤ 5 was performed. Concordance in AFC and AMH categorization between the pretreatment cycle and the ovarian‐stimulation cycle was assessed using Cohen's kappa (κ).

Results

There was no significant difference in the proportion of patients achieving a desired ovarian response between the AFC (54%) and AMH (49%) groups (P = 0.479). The median number of oocytes retrieved was nine vs seven (P = 0.070), and the median follicular output rate was 0.54 vs 0.55 (P = 0.764) in the AFC and AMH groups, respectively. Similar findings were observed on subgroup analysis of subjects with AFC ≤ 5 and AFC > 5 at the start of ovarian stimulation (P > 0.05 for all comparisons). There was moderate concordance between AFC and AMH measured in the pretreatment cycle and the stimulation cycle (κ = 0.478 and 0.587, respectively).

Conclusion

The proportion of women achieving a desired ovarian response following ovarian stimulation using the GnRH‐antagonist protocol is similar when the gonadotropin‐dosing algorithm used is based on AFC or serum AMH level. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.
Debating dams: The World Commission on Dams 20 years on
Authors: Schulz Christopher , Adams William M.
Published: July 2019

The World Commission on Dams (WCD) was a global environmental governance forum that worked between 1998 and 2000 to try to resolve long‐standing controversies between supporters and opponents of large dams. Its objectives were to assess the development effectiveness of large dams and to develop best practice guidelines for large dam construction and management, based on an extensive review of scientific evidence and wide‐ranging stakeholder consultation. This paper reviews literature discussing the WCD, to understand its influence on the debate on large dams and beyond. We find that its influence is debated within four main contexts: (a) interpretations of stakeholder responses to the WCD report and recommendations; (b) the persistence of the kinds of impacts of large dams that gave rise to the Commission's work; (c) the different visions for appropriate follow‐up strategies; and (d) insights from the WCD experience in the context of global environmental governance. Within these four contexts, we identify diverse opinions and directions of post‐WCD development and sources of disagreement on its merits and legacy, ranging from calls for its full implementation to dismissal and opposition. Commentators also differ in their assessment of whether the WCD sparked truly novel insights and propositions for dam decision‐making or whether it simply represented one among many other elements in the broader debate on dams. Most commonly, the WCD's work is cited in the context of persistent negative social and environmental impacts of dams: neither the impacts nor the controversy over large dams have ended.

This article is categorized under:

Engineering Water > Planning Water

Engineering Water > Sustainable Engineering of Water
Toric quiver asymptotics and Mahler measure: $$ \mathcal{N}=2 $$ BPS states
Authors: Zahabi Ali
Published: July 2019

Abstract

The BPS sector in

$$ \mathcal{N}=2 $$

N
=
2

, four-dimensional toric quiver gauge theories has previously been studied using the crystal melting model and dimer model. We introduce the Mahler measure associated with the statistical dimer model to study the large N limit of these quiver gauge theories. In this limit, the generating function of BPS states in a general toric quiver theory is studied and entropy, growth rate of BPS states and free energy of the quiver are obtained in terms of the Mahler measure. Moreover, a possible third-order phase transition in toric quivers is discussed. Explicit computations of the profile function, entropy density, BPS growth rate and phase structure of quivers are presented in concrete examples of the clover ℂ3, and resolved conifold

$$ \mathcal{C} $$

C

quivers. Finally, BPS growth rates of Hirzebruch

$$ \mathbb{F} $$

F

0, and ℂ3
/ℤ2 × ℤ2 orbifold quivers are obtained and a possible interpretation of the results for certain BPS black holes is discussed.
The role of singletons in S7 compactifications
Authors: Nilsson B.E.W. , Padellaro A. , Pope C.N.
Published: July 2019

Abstract

We derive the isometry irrep content of squashed seven-sphere compactifications of eleven-dimensional supergravity, i.e., the left-squashed (LS
7) with

$$ \mathcal{N} $$

N

= 1 and right-squashed (RS
7) with

$$ \mathcal{N} $$

N

= 0 supersymmetry, in a manner completely independent of the round sphere. Then we compare this result with the spectrum obtained by Higgsing the round sphere spectrum. This way we discover features of the spectra which makes it possible to argue that the only way the round spectrum can be related by a Higgs mechanism to the one of LS
7 is if the singletons are included in the round sphere spectrum. For this to work also in the RS
7 case it seems that the gravitino of the LS
7 spectrum must be replaced by a fermionic singleton present in the RS
7 spectrum.
A succession of near-orthogonal horizontal tectonic shortenings in the Paleoproterozoic Central Lapland Greenstone Belt of Fennoscandia: constraints from the world-class Suurikuusikko gold deposit
Authors: Sayab M. , Molnár F. , Aerden D. , Niiranen T. , Kuva J. , Välimaa J.
Published: July 2019

The relative and absolute timing of orogenic gold deposits in complex structural settings are active and challenging topics of research, especially in Precambrian greenstone belts. The Suurikuusikko gold deposit in Central Lapland Greenstone Belt is currently the largest primary gold producing deposit in Europe, located on a slight bend of the strike-slip Kiistala shear zone (KiSZ). Gold is refractory and locked inside arsenopyrite and pyrite. In this study, different structural features were investigated along the KiSZ from the recently stripped Etelä pit, which is the southern extension of the Suurikuusikko ore body. Our data source ranges from aeromagnetic to high-resolution aerial images, X-ray computed tomography scans of selected rock samples and regional geological and geophysical datasets. The KiSZ has recorded five discrete deformation phases, spanning between ca. 1.92 and 1.76 Ga. The refractory gold at the Suurikuusikko deposit formed during E-W contraction related to the D1 thrusting phase. This was followed by a N-S shortening event (D2), where most of the strain was taken up by the northern and southern thrusts. Tectonic vectors then switched from N-S to NE-SW and, as a result, dextral strike-slip regime (D3) commenced along the KiSZ. This event exsolved invisible gold from the sulfides and remobilized it along with fractures. A near-orthogonal switch of the regional stress regime from NE-SW to NW-SE flipped the kinematics of the KiSZ from dextral to sinistral (D4). The last deformation phase (D5) produced widespread veining under E-W contraction and secured gold mineralization at the Iso-Kuotko gold deposit within the KiSZ.
Mid-century emission pathways in Japan associated with the global 2 °C goal: national and global models’ assessments based on carbon budgets
Authors: Oshiro Ken , Gi Keii , Fujimori Shinichiro , van Soest Heleen L. , Bertram Christoph , Després Jacques , Masui Toshihiko , Rochedo Pedro , Roelfsema Mark , Vrontisi Zoi
Published: July 2019

This study assesses Japan’s mid-century low-emission pathways using both national and global integrated assessment models in the common mitigation scenario framework, based on the carbon budgets corresponding to the global 2 °C goal. We examine high and low budgets, equal to global cumulative 1600 and 1000 Gt-CO2 (2011–2100) for global models, and 36 and 31 Gt-CO2 (2011–2050) in Japan for national models, based on the cost-effectiveness allocation performed by the global models. The impacts of near-term policy assumption, including the implementation and enhancement of the 2030 target of the nationally determined contribution (NDC), are also considered. Our estimates show that the low budget scenarios require a 75% reduction of CO2 emissions by 2050 below the 2010 level, which is nearly the same as Japan’s governmental 2050 goal of reducing greenhouse gas emissions by 80%. With regard to near-term actions, Japan’s 2030 target included in the NDC is on track to meet the high budget scenario, whereas it is falling short for the low budget scenario, which would require emission reductions immediately after 2020. Whereas models differ in the type of energy source on which they foresee Japan basing its decarbonization process (e.g., nuclear- or variable renewable energy-dependent), the large-scale deployment of low-carbon energy (nuclear, renewable, and carbon capture and storage) is shared across most models in both the high and low budget scenarios. By 2050, low-carbon energy represents 44–54% of primary energy and 86–97% of electricity supply in the high and low budget scenarios, respectively.
Cis-Hetero-Misogyny Online
Authors: Richardson-Self Louise
Published: July 2019

This article identifies five genres of anti-queer hate speech found in The Australian’s Facebook comments sections, exposing and analyzing the ways in which such comments are used to derogate cisgender and (often) heterosexual women. One may be tempted to think of cis-het women as third-party victims of queerphobia; however, this article argues that these genres of anti-queer speech are, in fact, misogynistic. Specifically, it argues that these are instances of cis-hetero-misogynistic hate speech. Cis-hetero-misogyny functions as the “law enforcement branch” of a cis-hetero-patriarchal gender order. Given the existence of such an order, it is clear that cis-het women’s liberation is inextricable from queer liberation (and vice versa). This article argues that to facilitate allyship and challenge this gender order—the order that elicits such hate speech acts—we need an epistemological revolution in the way we recognize and re-cognize human difference.
Who Sets the Aggressive Popularity Norm in Classrooms? It’s the Number and Strength of Aggressive, Prosocial, and Bi-Strategic Adolescents
Authors: Laninga-Wijnen Lydia , Harakeh Zeena , Dijkstra Jan Kornelis , Veenstra René , Vollebergh Wilma
Published: July 2019

Previous work has shown that during adolescence, classrooms vary greatly in the extent to which aggression is rewarded with popularity (the ‘popularity norm’). Aggressive popularity norms may promote the proliferation of aggression and negatively affect the classroom climate. It is, however, unknown how these norms emerge in the first place. This longitudinal study therefore investigated whether aggressive popularity norms can be predicted by the classroom composition of students. We examined whether the prevalence of six student types - socially and non-socially dominant prosocial, aggressive, and bi-strategic adolescents (adolescents who are both highly prosocial and aggressive) - contributed to the norm by establishing a popularity hierarchy: strong classroom asymmetries in popularity. We collected peer-nominated data at three secondary schools in the Netherlands (SNARE-study;Nstudents = 2843;Nclassrooms = 120; 51.4% girls;Mage = 13.2). Classroom-level regression analyses suggest that the classroom percentage of socially dominant aggressive and bi-strategic students predicted higher aggressive popularity norms, both directly and by enhancing the classrooms’ popularity hierarchy. Instead, the presence of non-socially dominant aggressive students and socially dominant prosocial students contributed toloweraggressive popularity norms. Socially dominant prosocial students also buffered against the role of socially dominant aggressive adolescents in the aggressive popularity norm (moderation), but not against bi-strategic adolescents’ role. Our findings indicate that interventions aimed at reducing aggressive popularity norms should first and foremost take the composition of classrooms at the start of the school year into account; and should not only encourage prosocial behavior, but also actively discourage aggression.
Pore structure characterization based on joint numerical and experimental study: a case study of Nanpu Sag
Authors: Li Hatitao , Deng Shaogui , Yuan Xiyong , Hu Xufei , Niu Yunfeng
Published: July 2019

Petrophysical properties such as acoustic velocity, resistivity and nuclear magnetic resonance are greatly depending on the pore structures. This is because the pore structures could control the elastic modulus, conductive path and seepage distribution of the rock. The theoretical simulation and acoustic–electrical–nuclear magnetic resonance joint experiments were used to study the pore structure control action of acoustic, electrical and nuclear magnetic characteristics by taking the sandstone samples of Nanpu Sag as an example which the pore structure of the samples was classified based on the mercury intrusion fractal curve. It is found that the control action of pore structure type on the variation law of longitudinal and transverse wave velocity is mainly affected by the aspect ratio of pores; the effect of pore structure type on resistivity change is mainly affected by pore–throat ratio and tortuosity; the influence of pore structure on nuclear magnetic changes is mainly affected by pore size factors.
A pragmatic approach for optimizing gas lift operations
Authors: Garrouch Ali A. , Al-Dousari Mabkhout M. , Al-Sarraf Zahra
Published: July 2019

The oil flow rate in a single vertical well undergoing gas lift operations is complicated by three factors: (1) The flow is driven by gas injection, in addition to the fluid flow potential gradient applied along the well, (2) the well is interfaced with a porous and permeable reservoir contributing with a fluid feed, and (3) the wellbore geometry may consist of concentric pipes of varying diameters and lengths, rather than a single-diameter pipe. Dimensional analysis is applied to this complex, highly nonlinear production problem, in order to develop empirical models for predicting the optimal gas injection rate and the maximum oil production rate that may be produced from continuous gas lift operations. Two pairs of coupled dimensionless groups are revealed. The first pair consists of a dimensionless pressure drop (π1) adjusted to the complex wellbore geometry, and a dimensionless ratio of kinetic to viscous forces (π2) which accounts for the porous medium feed. A constructed database for 388 vertical wells producing by continuous gas lift operations has been used to validate the dimensionless groups. A power-law relation is revealed between the dimensionless groups π1 and π2, allowing to construct an analytical model for predicting the maximum oil production rate that corresponds to the optimal gas injection rate. The second pair consists of two groups denoted χ1 and χ2. The group χ1 is a dimensionless pressure drop with adjustment being augmented to account for the temperature effects on gas flow. Similar to π2, the dimensionless group χ2 is a ratio of kinetic to viscous forces, adjusted to account for the porous medium feed. However, χ2 is a function of the injection rate, instead of the oil production rate. Likewise, a power-law relation is revealed between χ1 and χ2, allowing to construct an analytical model for predicting the optimal gas injection rate. All power-law relations yield high correlation coefficients when the validation data are segregated according to a discrete productivity index. The analytical models developed by applying dimensional analysis appear to capture the physical controls of gas lift operations. Intuitively, the optimal gas injection rate depends on the pressure gradient along the pipe, the wellbore geometry, the temperature conditions at the bottom of the well and in the stock-tank, the oil density, and on the productivity index. Similarly, the maximum oil production rate, corresponding to the optimal gas injection rate, depends on the pressure gradient along the pipe, the wellbore geometry, the oil density, the productivity index which is implicitly affected by the oil permeability, and viscosity. Unlike multivariate nonlinear regression analysis, the application of dimensional analysis for deriving the analytical models, presented in this study, does not require a presumed functional relationship. In retrospect, dimensional analysis evades the guessing process associated with nonlinear regression analysis.
Carbonated water injection: an efficient EOR approach. A review of fundamentals and prospects
Authors: Bisweswar Ghosh , Al-Hamairi Abdullah , Jin Soo
Published: July 2019

Carbonated water injection (CWI) might be an efficient alternate to CO2injection technique. In CWI, CO2exists as a dissolved phase and not as a free phase; thus, it eliminates some challenges encountered in CO2injection such as poor sweep efficiency and gravity segregation. In CWI, the density and viscosity of water become higher than normal due to the CO2dissolution, thereby reducing the gravity segregation and channeling effect. This article is a comprehensive review on how carbonated water flooding has evolved over the time and captured salient features on the mechanisms involved in its role in enhanced oil recovery. The aspects reviewed in this article include a brief comparison of conventional CO2injection and carbonated water injection and the benefits thereof. Solubility of CO2in water, brine and oil phases is discussed in detail with valid correlations. A brief history of the development of CWI in the laboratory and field information is captured from 1905s to the present followed by the possible mechanisms and principle of CWI reported by various authors. This article also captured the latest findings on the beneficial effect of hybridizing CWI with smart water technologies.
Subcritical CO2 effects on kaolinite fines transport in porous limestone media
Authors: Mahalingam S. , Pranesh Venkat , Kanimozhi B. , Thamizhmani Vivek , Arun Selvakumar T.
Published: July 2019

Carbonate reservoirs account for 60% share in global oil reserves, and CO2-EOR process is employed in these carbonate fields for effective oil recovery and retention as well. Recent research reports that fines migration may lead to reservoir formation damage in oil bearing limestone and dolomite rocks. Although carbonate reservoirs are poor in clay minerals, some mass of clay fines existence in certain carbonate formations will cause severe damage to permeability and well productivity. This paper reports the single-phase flow of subcritical CO2 in porous limestone rock core containing kaolinite clay fines. Fines are natural reservoir minerals (example, quartz) and clay particles such as kaolinite, illite, feldspar, smectite, and montmorillonite. But, this paper explores this CO2-clay fines behavior in limestone rock as a function of kaolinite. So, two sets of core flood experiments were performed in the rock temperatures 120 °C and 160 °C. Initially, kaolinite clay has been injected into the limestone core in the form of suspension and then dried for hours in order to retain the solid fines in the internal pore chambers of the core. After that, the CO2 under subcritical condition has been injected into the porous limestone core for fines mobilization and injected gas recovery. The major observations that are reported from the experimental tests are there is an increase in gas saturation for increasing injection time. Steady rise of heat transfer coefficient and enthalpy was noted for increasing gas saturation and time. Concentration of fines linearly soars with respect to elevating PVI and permeability declines for rising time. Pressure in the limestone core shows abnormal and nonlinear variation. Finally, gas discharge rate declines for increasing injection time. Experimental data are tested against the statistical model (regression), and the outcome indicated good agreement. Overall, this paper has successfully established the CO2 effects on kaolinite clay fines behavior and its impact on oil recovery in carbonate fields.
Singular vector distribution of sample covariance matrices
Authors: Ding Xiucai
Published: July 2019

We consider a class of sample covariance matrices of the formQ=TXX*T*, whereX= (xij) is anM×Nrectangular matrix consisting of independent and identically distributed entries, andTis a deterministic matrix such thatT*Tis diagonal. Assuming thatMis comparable toN, we prove that the distribution of the components of the right singular vectors close to the edge singular values agrees with that of Gaussian ensembles provided the first two moments ofxijcoincide with the Gaussian random variables. For the right singular vectors associated with the bulk singular values, the same conclusion holds if the first four moments ofxijmatch those of the Gaussian random variables. Similar results hold for the left singular vectors if we further assume thatTis diagonal.
WHAT'S IN A NAME? THE EVOLVING ROLE OF THE FRVMENTARII
Authors: McCunn Stuart
Published: July 2019

From the first century a.d. to the late third there existed a group of soldiers known as the frumentarii. Centralized in the late first century, they became an increasingly important force throughout the second century until Diocletian abolished them at the end of the third. Modern scholarship has usually seen their purpose as encompassing three roles: couriers, military police and secret police, with the last attracting the most attention.
Weight bias and health care utilization: a scoping review
Authors: Alberga Angela S. , Edache Iyoma Y. , Forhan Mary , Russell-Mayhew Shelly
Published: July 2019

Aim:

The purpose of this scoping review was to explore the evidence on how perceptions and/or experiences of weight bias in primary health care influence engagement with and utilization of health care services by individuals with obesity.

Background:

Prior studies have found discrepancies in the use of health care services by individuals living with obesity; a greater body mass index has been associated with decreased health care utilization, and weight bias has been identified as a major barrier to engagement with health services.

Methods:

PubMed was searched from January 2000 to July 2017. Four reviewers independently selected 21 studies examining perceptions of weight bias and its impact on engagement with primary health care services.

Findings:

A thematic analysis was conducted on the 21 studies that were included in this scoping review. The following 10 themes were identified: contemptuous, patronizing, and disrespectful treatment, lack of training, ambivalence, attribution of all health issues to excess weight, assumptions about weight gain, barriers to health care utilization, expectation of differential health care treatment, low trust and poor communication, avoidance or delay of health services, and ‘doctor shopping’. Overall, our scoping review reveals how perceptions and/or experiences of weight bias from primary care health professionals negatively influence patient engagement with primary health care services.
The Emergence of Professional Law Librarianship and the Professional Law Librarian: the History of BIALL in Context
Authors: Holborn Guy
Published: July 2019

Guy Holborn revisits the research he carried out in preparing the chapter on law libraries from 1850 to 2000 in the Cambridge History of Libraries in Britain and Ireland. Much of the material he gathered was not included in the chapter as published for reasons of space. Drawing from both the previously published chapter and the unpublished material, he selects four themes relevant to BIALL in its 50th anniversary year: legal education and law libraries, the development of law firms and their information services, the content of law libraries and the information needs of the profession, and the emergence of the professional law librarian.
Hemispheric Asymmetry of the Pacific Shallow Meridional Overturning Circulation
Authors: Zeller Mathias , McGregor Shayne , Spence Paul
Published: July 2019

The shallow subtropical cells (STCs) in the Pacific Ocean are thought to modulate the background state that the El Niño‐Southern Oscillation (ENSO) operates in. This modulation is proposed to impact the frequency and intensity of ENSO events and their teleconnections. We use a high‐resolution ocean model to investigate the volume transports associated with the STC branches along 5° N and 5° S. We find three prominent differences between the Southern hemisphere (SH) STC and the Northern hemisphere (NH) STC: (i) the NH STC varies 26% stronger than the SH STC; (ii) the NH STC appears to lead the SH STC by 3 months which causes the NH and SH STCs to play different roles during the course of El Niño and La Niña events; and (iii) in spite of the relative symmetry of the wind stress trends, the STCs have differing decadal trends, with the SH STC clearly dominating the changes in the post‐1993 period. To investigate the mechanisms driving the STC variability, we identify winds that are linearly and nonlinearly related to ENSO to force the ocean model. The hemispheric difference in interannual variance as well as the phase difference between the STCs can be explained with ENSO forcing. Our results suggest ENSO to be an important factor in modulating its own background state, with a prominent role for the winds that are nonlinearly related to ENSO. The decadal trends and their interhemispheric disparity, however, cannot be reproduced by our targeted ENSO experiments.
Composition, Provenance, and Tectonic Setting of the Southern Kangurtag Accretionary Complex in the Eastern Tianshan, NW China: Implications for the Late Paleozoic Evolution of the North Tianshan Ocean
Authors: Chen Zhenyu , Xiao Wenjiao , Windley Brian F. , Schulmann Karel , Mao Qigui , Zhang Zhiyong , Zhang Ji'en , Deng Chen , Song Shuaihua
Published: July 2019

The Kangurtag belt in the Eastern Tianshan, connecting the Dananhu Arc with the Central Tianshan Arc, contains diagnostic rocks of accretionary origin, and thus provides key information about the evolution of the North Tianshan Ocean. The Southern Kangurtag belt is composed of two types of mélange. Type I mélange consists of Enriched Mid‐Ocean Ridge Basalt‐type pillow basalts, draped by biohermal limestones and carbonate‐siliceous sediments of a slope facies, and siliceous argillites from a hemipelagic‐pelagic environment that together make up a seamount assemblage. In Type II mélange, Normal Mid‐Ocean Ridge Basalt and ribbon cherts were dismembered and entrained in a clastic matrix, showing a “block‐in‐matrix” structure. Detrital zircons of four sandstones from Devonian and Carboniferous strata within the mélanges have a predominant age population of 410–430 Ma and a distinct Proterozoic cluster around 1.4–1.6 Ga. The εHf(t) values of Phanerozoic zircons range from −25.1 to +8.6. Such age patterns, typical of the Central Tianshan Arc, and the Hf isotopic data indicate that these sedimentary successions were deposited on the northern margin of the Central Tianshan Arc. The youngest detrital zircon age of 317 Ma provides an upper limit for the time of formation of the Southern Kangurtag accretionary complex. Therefore, we suggest that the Southern Kangurtag belt comprises an accretionary complex that developed during southward subduction of the North Tianshan Ocean beneath the Central Tianshan Arc. This subduction began in the Early Ordovician and may have lasted until the Late Carboniferous–Permian.
Looking Straight at the Sun
Authors: Joel Lucas
Published: July 2019

Thanks to some crucial calibrations, the world’s biggest solar telescope will have a clearer view of the Sun.
Updated Temperature Data Give a Sharper View of Climate Trends
Authors: Zhang Huai-Min , Lawrimore Jay , Huang Boyin , Menne Matthew , Yin Xungang , S�nchez-Lugo Ahira , Gleason Byron , Vose Russell , Arndt Derek , Rennie J. , Williams Claude
Published: July 2019

The latest version of NOAA’s Global Surface Temperature Dataset improves coverage over land and sea and improves the treatment of historical changes in observational practices.
Hearing Garners Bipartisan Support for Scientific Integrity
Authors: Showstack Randy
Published: July 2019

Democrats hope Republicans will decide to cosponsor legislation to codify scientific integrity procedures at federal agencies.
Kinematics of Active Deformation in the Malawi Rift and Rungwe Volcanic Province, Africa
Authors: Ebinger C. J. , Oliva Sarah Jaye , Pham Thi‐Quan , Peterson Katherine , Chindandali Patrick , Illsley‐Kemp Finnigan , Drooff Connor , Shillington Donna J. , Accardo Natalie J. , Gallacher Ryan J. , Gaherty J. , Nyblade Andrew A. , Mulibo Gabriel
Published: July 2019

Although the deep, wide basins of the Western rift, Africa, have served as analogues for the evolution of half‐graben basins, the geometry and kinematics of the border, intrabasinal, and transfer fault systems have been weakly constrained. Despite the >100‐km‐long fault systems bounding basins, little was known of seismicity patterns or the potential for M > 7.5 earthquakes. Using our new local earthquake database from the 2013‐2015 Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) seismic array (57 onshore, 32 lake‐bottom stations) and TANGA14 (13 stations), we examine the kinematics and extension direction of the Rungwe Volcanic Province and northern Malawi rift. We relocated earthquakes using a new 1‐D velocity model and both absolute and double‐difference relocation methods. Local magnitudes of 1,178 earthquakes within the array are 0.7 < ML < 5.2 with a b‐value 0.77 ± 0.03, and magnitude of completeness ML 1.9. Focal mechanism solutions for 63 earthquakes reveal predominantly normal and oblique‐slip motion, and full moment tensor solutions for ML 4.5, 5.2 earthquakes have centroid depths within 2 km of catalog depths. The preferred nodal planes dip more than 40° from surface to >25‐km depths. Extension direction from local earthquakes and source mechanisms of teleseismically detected earthquakes are approximately N58°E and N65°E, respectively, refuting earlier interpretations of a NW‐SE transform fault system. The low b‐value indicating strong coupling across crustal‐scale border faults, border fault lengths >100 km, and evidence for aseismic deformation together indicate that infrequent M > 7.5 earthquakes are possible within this cratonic rift system.
Variations in Solar Activity Across the Spörer Minimum Based on Radiocarbon in Danish Oak
Authors: Fogtmann‐Schulz A. , Kudsk S. G. K. , Trant P. L. K. , Baittinger C. , Karoff C. , Olsen J. , Knudsen M. F.
Published: July 2019

Several aspects concerning the origin and nature of grand solar minima remain unclear, and more high‐resolution 10Be and 14C records are needed to improve our understanding of these phenomena. Here, we report 137 new high‐precision, annually resolved radiocarbon concentrations based on oak from the Danish dendrochronology. The new record covers a period (CE 1432–1578) that encompasses most of the penultimate grand solar minima known as the Spörer Minimum. A detailed comparison between the Spörer and Maunder (CE 1640–1720) minima shows that the Spörer Minimum is associated with enhanced Δ14C variability in a band centered around the 11‐year Schwabe cycle from CE 1450 to 1479 and between CE 1545 and 1578, whereas little 11‐year variability is observed from CE 1479 to 1539. In contrast, we only observe enhanced 11‐year variability after the end of the Maunder Minimum at CE 1722–1744, which could indicate that the nature and origin of the two minima were different.
Frictional Stabilities on Induced Earthquake Fault Planes at Fox Creek, Alberta: A Pore Fluid Pressure Dilemma
Authors: Shen L. W. , Schmitt D. R. , Schultz R.
Published: July 2019

Earthquakes induced during hydraulic fracturing operations have occurred in a number of locales. However, in situ studies aimed to discern the triggering mechanism remain exclusively statistical in their nature. Here we calculate the fault slip tendencies of 11 hydraulic fracturing induced earthquakes in a historically aseismic area using a recently constructed quantitative model for the in‐situ stresses. It is shown that the ambient pore pressures of the nearby Duvernay unconventional reservoirs can provide enough ΔPf triggering fault movement. The local fluid pressures acting on the fault could readily be increased above the critical value if hydraulic connection exists between the fault and a propagating hydraulic fracture. The critical pressures necessary to induce slip are estimated using a probabilistic model that incorporates uncertainties of stress and fault's mechanical properties. These critical pressures are greater than the expected hydrostatic pressure but less the pore pressures of nearby unconventional reservoirs.
Seasonal Prediction Potential for Springtime Dustiness in the United States
Authors: Pu Bing , Ginoux Paul , Kapnick Sarah B. , Yang Xiaosong
Published: July 2019

Most dust forecast models focus on short, subseasonal lead times, that is, 3 to 6 days, and the skill of seasonal prediction is not clear. In this study we examine the potential of seasonal dust prediction in the United States using an observation‐constrained regression model and key variables predicted by a seasonal prediction model developed at National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory, the Forecast‐Oriented Low Ocean Resolution (FLOR) model. Our method shows skillful predictions of spring dustiness 3 to 6 months in advance. It is found that the regression model explains about 71% of the variances of dust event frequency over the Great Plains and 63% over the southwestern United States in March‐May from 2004 to 2016 using predictors from FLOR initialized on 1 December. Variations in springtime dustiness are dominated by springtime climatic factors rather than wintertime factors. Findings here will help development of a seasonal dust prediction system and hazard prevention.
Changing Salinity Gradients in the Baltic Sea As a Consequence of Altered Freshwater Budgets
Authors: Kniebusch Madline , Meier H.E. Markus , Radtke Hagen
Published: July 2019

Climate change is expected to enhance the hydrological cycle in northern latitudes reducing the salinity in the Baltic Sea, a land‐locked marginal sea with a large catchment area located in northern Europe. With the help of ocean simulations forced by historical atmospheric and hydrological reconstructions and local observations, we analyzed long‐term changes in the sea surface salinity of the Baltic Sea as well as its latitudinal gradient. The variability of both is dominated by multidecadal oscillations with a period of about 30 years, while both atmospheric variables, wind and river runoff, contribute to this variability. Centennial changes show a statistically significant positive trend in the North‐South gradient of sea surface salinity for 1900–2008. This change is mainly attributed to increased river runoff from the northernmost catchment indicating a footprint of the anthropogenic impact on salinity with consequences for the marine ecosystem and species distributions.
Energetics of Radiatively Heated Ice‐Covered Lakes
Authors: Winters Kraig B. , Ulloa Hugo N. , Wüest Alfred , Bouffard Damien
Published: July 2019

We derive the mechanical energy budget for shallow, ice‐covered lakes energized by penetrative solar radiation. Radiation increases the available and background components of the potential energy at different rates. Available potential energy drives under‐ice motion, including diurnally active turbulence in a near‐surface convective mixing layer. Heat loss at the ice‐water interface depletes background potential energy at a rate that depends on the available potential energy dynamics. Expressions for relative energy transfer rates show that the pathway for solar energy is sensitive to the convective mixing layer temperature through the nonlinear equation of state. Finally, we show that measurements of light penetration, temperature profiles resolving the diffusive boundary layer, and an estimate of the kinetic energy dissipation rate can be combined to estimate the forcing rate, the rate of heat loss to the ice, and efficiencies of the energy pathways for radiatively driven flows.
Quasiperiodic Rising Structures in the E‐F Valley Region Below the Equatorial Plasma Bubble: A Numerical Study
Authors: Savio S. , Sousasantos J. , Pimenta A. A. , Yang G. , Kherani E. A. , Wang C. , Liu Z.
Published: July 2019

This paper presents a numerical study aiming to understand the generating mechanism of poorly studied equatorial plasma irregularities known as equatorial quasiperiodic echoes. Employing a two‐dimensional model of the collisional interchange instability, the simulations are able to reproduce the spatial periodic features of this kind of irregular structures. The usage of an instability seeding source considering an overlap of two gravity waves with different wavelengths was capable to produce such quasiperiodic structures. The results suggest that the penetration of the equatorial plasma bubble fringe fields in typical altitudes of the valley region may be the physical mechanism responsible for the structures. Additionally, the simulation results indicate that the lower wavelength gravity wave dominates over the quasiperiodic nature of the these irregularities. The simulations results present considerable agreement with radar and in situ measurements of these quasiperiodic structures.
Temperature Dependence of Plasmaspheric Ion Composition
Authors: Goldstein J. , Gallagher D. , Craven P. D. , Comfort R. H. , Genestreti K. J. , Mouikis C. , Spence H. , Kurth W. , Wygant J. , Skoug R. M. , Larsen B. A. , D. Reeves G. , De Pascuale S.
Published: July 2019

We analyze a database of Dynamics Explorer‐1 (DE‐1) Retarding Ion Mass Spectrometer densities and temperatures to yield the first explicit measure of how cold ion concentration depends on temperature. We find that cold H+ and He+ concentrations have very weak dependence on temperature, but cold O+ ion concentration increases steeply as these ions become warmer. We demonstrate how this result can aid in analyzing composition data from other satellites without spacecraft potential mitigation, by applying the result to an example using data from the Van Allen Probes mission. Measurement of light ion concentrations above 1 electron volt (eV) are a reasonable proxy for the concentrations of colder (eV) ions. Warmer O+ ion concentrations may be extrapolated to colder temperatures using our fit to the statistical distribution versus temperature.
Lower Ionospheric Conductivity Modification Above a Thunderstorm Updraught
Authors: Koh K. , Bennett A. , Ghilain S. , Liu Z. , Pedeboy S. , Peverell A. , Füllekrug M.
Published: July 2019

Lightning has previously been observed to disturb the lower ionosphere. These lightning‐induced ionospheric perturbations were observed as disturbances on subionospheric low‐frequency radio wave propagation with fast rise times <3 s and gradual recoveries of duration >10 s. Most of these disturbances were observed during night time when ionospheric conditions are most favorable. Here, a daytime perturbation in the lower ionosphere was observed using subionospheric radio remote sensing. The disturbance exhibits a ∼60 s rise time with a gradual recovery of >200 s. No cloud to ground lightning was coincident with the disturbance onset, however, the intracloud lightning activity of a thunderstorm over the radio receiver was seen to increase at the time of the disturbance. Therefore, the observed disturbance is unlikely to be caused by lightning, yet appears to be associated with the thunderstorm. It is proposed that this disturbance is produced by a pronounced increase in updraught strength that produced a significant change in the quasi‐static electrification of the thunderstorm. This change in electrification is evident in the increase in the intracloud lightning activity of the thunderstorm. The observation provides further evidence of the ionospheric heating effect of thundercloud charge which has implications for lower atmosphere‐ionosphere energy coupling and possibly sprite initiation.
Memorable Events During a Research Career
Authors: Sheeley Neil R.
Published: July 2019

In this paper, I sketch a path through my research career in solar and heliospheric physics, recalling some memorable events and discoveries that occurred along the way. This chain of events begins with an influential Time magazine article in 1955 and progresses through a summer at Bell Labs, 9 years at Caltech, 7 years at the Kitt Peak National Observatory, 43 years at the Naval Research Laboratory, and ends with a digitized map of the Sun's Ca II K‐Line emission in 1919 when the AGU was born. Accidents and puzzling results are often the keys to progress and should be examined carefully.
Retrieval of Wintertime Sea Ice Production in Arctic Polynyas Using Thermal Infrared and Passive Microwave Remote Sensing Data
Authors: Preußer Andreas , Ohshima Kay I. , Iwamoto Katsushi , Willmes Sascha , Heinemann Günther
Published: July 2019

Precise knowledge of wintertime sea ice production in Arctic polynyas is not only required to enhance our understanding of atmosphere‐sea ice‐ocean interactions but also to verify frequently utilized climate and ocean models. Here, a high‐resolution (2‐km) Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared satellite data set featuring spatial and temporal characteristics of 17 Arctic polynya regions for the winter seasons 2002/2003 to 2017/2018 is directly compared to an akin low‐resolution Advanced Microwave Scanning Radiometer‐EOS (AMSR‐E) passive microwave data set for 2002/2003 to 2010/2011. The MODIS data set is purely based on a 1‐D energy‐balance model, where thin‐ice thicknesses (≤ 20 cm) are directly derived from ice‐surface temperature swath data and European Centre for Medium‐Range Weather Forecasts Re‐Analysis‐Interim atmospheric reanalysis data on a quasi‐daily basis. Thin‐ice thicknesses in the AMSR‐E data set are derived empirically. Important polynya properties such as areal extent and potential thermodynamic ice production can be estimated from both pan‐Arctic data sets. Although independently derived, our results show that both data sets feature quite similar spatial and temporal variations of polynya area (POLA) and ice production (IP), which suggests a high reliability. The average POLA (average accumulated IP) for all Arctic polynyas combined derived from both MODIS and AMSR‐E are 1.99×105 km2 (1.34×103 km3) and 2.29×105 km2 (1.31×103 km3), respectively. Narrow polynyas in areas such as the Canadian Arctic Archipelago are notably better resolved by MODIS. Analysis of 16 winter seasons provides an evaluation of long‐term trends in POLA and IP, revealing the significant increase of ice formation in polynyas along the Siberian coast.
The Response of Tropical Organized Convection to El Niño Warming
Authors: Sullivan Sylvia C. , Schiro Kathleen A. , Stubenrauch Claudia , Gentine Pierre
Published: July 2019

Convective organization has a large impact on precipitation and feeds back on larger‐scale circulations in the tropics. The degree of this convective organization changes with modes of climate variability like the El Niño–Southern Oscillation (ENSO), but because organization is not represented in current climate models, a quantitative assessment of these shifts has not been possible. Here, we construct multidecade satellite climatologies of occurrence of tropical convective organization and its properties and assess changes with ENSO phase. The occurrence of organized deep convection becomes more concentrated, increasing threefold in the eastern and central Pacific during El Niño and decreasing twofold outside of these regions. Both horizontal extent of the cold cloud shield and convective depth increase in regions of positive sea surface temperature anomaly (SSTa); however, the regions of greatest convective deepening are those of large‐scale ascent, rather than those of warmest SSTa. Extent decreases with SSTa at a rate of about 20 km/K, while the SSTa dependence of depth is only about 0.2 K/K. We introduce two values to describe convective changes with ENSO more succinctly: (1) an information entropy metric to quantify the clustering of convective system occurrences and (2) a growth metric to quantify deepening relative to spreading over the system lifetime. Finally, with collocated precipitation data, we see that rainfall attributable to convective organization jumps up to 5% with warming. Rain intensity and amount increase for a given system size during El Niño, but a given rain amount may actually fall with higher intensity during La Niña.
Can Machines Learn to Predict Weather? Using Deep Learning to Predict Gridded 500‐hPa Geopotential Height From Historical Weather Data
Authors: Weyn Jonathan A. , Durran Dale R. , Caruana Rich
Published: July 2019

We develop elementary weather prediction models using deep convolutional neural networks (CNNs) trained on past weather data to forecast one or two fundamental meteorological fields on a Northern Hemisphere grid with no explicit knowledge about physical processes. At forecast lead times up to 3 days, CNNs trained to predict only 500‐hPa geopotential height easily outperform persistence, climatology, and the dynamics‐based barotropic vorticity model, but do not beat an operational full‐physics weather prediction model. These CNNs are capable of forecasting significant changes in the intensity of weather systems, which is notable because this is beyond the capability of the fundamental dynamical equation that relies solely on 500‐hPa data, the barotropic vorticity equation. Modest improvements to the CNN forecasts can be made by adding 700‐ to 300‐hPa thickness to the input data. Our best performing CNN does a good job of capturing the climatology and annual variability of 500‐hPa heights and is capable of forecasting realistic atmospheric states at lead times of 14 days. Although our simple models do not perform better than an operational weather model, machine learning warrants further exploration as a weather forecasting tool; in particular, the potential efficiency of CNNs might make them attractive for ensemble forecasting.