bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuity of Constitutional Government during a Pandemic: Considering the Concept in Canada's Emergency Management Act
Authors: McDougall Andrew
Published: April 2020

This research note examines the undefined meaning of the government's obligations to ensure “continuity of constitutional government” (CCG) as provided for in section 4(l) of the Emergency Management Act, S.C. 2007, c. 15 (Canada, 2007). Specifically, that section gives the minister of public safety and emergency preparedness the responsibility for “establishing the necessary arrangements for the continuity of constitutional government in the event of an emergency,” but the term is itself undefined. The article will canvass the origin of the term and its relationship to other so-called continuity of government (COG) concepts, along with some legal written opinion on what the term might in practice mean, should the minister ever be charged with discharging this responsibility. It will conclude with some final thoughts on the relevance of the CCG concept to the current pandemic. Given that the COVID-19 virus has infected Sophie Grégoire Trudeau, the prime minister's wife, forced a drastically reduced and possibly “virtual” federal Parliament, placed the British prime minister in intensive care and led to the self-isolation of many world leaders, the topic is relevant to Canada in 2020.
Density jump for parallel and perpendicular collisionless shocks
Authors: Bret Antoine , Narayan Ramesh
Published: April 2020

In a collisionless shock, there are no binary collisions to isotropize the flow. It is therefore reasonable to ask to which extent the magnetohydrodynamics (MHD) jump conditions apply. Following up on recent works which found a significant departure from MHD in the case of parallel collisionless shocks, we here present a model allowing to compute the density jump for collisionless shocks. Because the departure from MHD eventually stems from a sustained downstream anisotropy that the Vlasov equation alone cannot specify, we hypothesize a kinetic history for the plasma, as it crosses the shock front. For simplicity, we deal with non-relativistic pair plasmas. We treat the cases of parallel and perpendicular shocks. Non-MHD behavior is more pronounced for the parallel case where, according to MHD, the field should not affect the shock at all.
דיכוי נורמות מתירניות במשפחה היהודית בימי הביניים
Authors: יהלום שלם
Published: April 2020

מחקר זה יסקור את יחסה של ההלכה היהודית בימי הביניים כלפי יחסי מין שאינם יכולים להוביל לפריון. המחקר יתמקד בבתי המדרש של גרמניה וצרפת, ובמעבר של ההלכה האשכנזית במאה השלוש עשרה לבית המדרש המתפתח בקטלוניה. ספר היסוד של ההלכה היהודית הוא התלמוד הבבלי, והדיונים ההלכתיים שהתפתחו בבתי המדרש של אשכנז וקטלוניה התמקדו במובאות התלמודיות. לכן נציג תחילה את הרקע התלמודי.
Effective multi-dialectal arabic POS tagging
Authors: Darwish Kareem , Attia Mohammed , Mubarak Hamdy , Samih Younes , Abdelali Ahmed , Màrquez Lluís , Eldesouki Mohamed , Kallmeyer Laura
Published: April 2020

This work introduces robust multi-dialectal part of speech tagging trained on an annotated data set of Arabic tweets in four major dialect groups: Egyptian, Levantine, Gulf, and Maghrebi. We implement two different sequence tagging approaches. The first uses conditional random fields (CRFs), while the second combines word- and character-based representations in a deep neural network with stacked layers of convolutional and recurrent networks with a CRF output layer. We successfully exploit a variety of features that help generalize our models, such as Brown clusters and stem templates. Also, we develop robust joint models that tag multi-dialectal tweets and outperform uni-dialectal taggers. We achieve a combined accuracy of 92.4% across all dialects, with per dialect results ranging between 90.2% and 95.4%. We obtained the results using a train/dev/test split of 70/10/20 for a data set of 350 tweets per dialect.
Interaction of Epididymal Epithelia and their Secretions with Spermatozoa Supports Functional and Morphological Changes During Long-Term Storage in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)
Authors: Tarique Imran , Tariq Mansoor , Bai Xuebing , Wenjia Qu , Yang Ping , Huang Yufei , Sheng Yang , Vistro Waseem Ali , Chen Quisheng
Published: April 2020

Post-testicular maturation of spermatozoa is crucial for attaining the morphological and functional capabilities needed for successful fertilization. Epididymal epithelia offer a favorable environment for spermatozoa that are stored long term in the turtle epididymis; however, sperm–epithelial interactions during storage, which are enormously important for sperm functional and morphological maturation, are still largely unknown in turtles. The present study examined the epididymis during the sperm-storage period (November–April) in the Chinese soft-shelled turtle (Pelodiscus sinensis). Light and transmission electron microscopy were used to determine the cellular features of each epididymal segment (caput, corpus, and cauda) and their epithelial interactions with the spermatozoa. Spermatozoa were mainly located in the lumena of caput, corpus, and cauda epididymides. Numerous spermatozoa were bound to apical surfaces of the epithelia, and several were even embedded in the epithelial cytoplasm of the caput and corpus epididymides. No embedded spermatozoa were found in the cauda epididymis. In all epididymal segments, principal and clear cells showed the synthetic activity, evidenced by a well-developed endoplasmic reticulum network and high and low electron-dense secretory materials, respectively. Principal and clear cells in the caput and corpus segments showed embedded spermatozoa in electron-dense secretions and in the lipid droplets within the cytoplasm. No lysosomes were observed around the embedded spermatozoa. The lumena of the caput and corpus segments showed few apocrine and low electron density secretions. In the lumen of the cauda epididymidis, different secretions, such as holocrine with low and high electron density and their fragmentation, apocrine, and dictyosome, were found and are summarized. Altogether, sperm physical interactions with secretions either in the cytoplasm of epithelium or in the lumen may support the viability, morphological maintenance, and transfer of various proteins involved in long-term sperm storage in the turtle. This interaction could help us to understand the mechanisms of long-term sperm storage and provide more insights into the reproductive strategies of turtle sperm preservation.
Semi-Supervised Nonnegative Matrix Factorization of Wide-Field Fluorescence Microscopic Images for Tissue Diagnosis
Authors: Soman Shania M. , Rekha Charuvil Radhakrishna Pillai , Santhakumar Hema , Narendrakumar Uttamchand , Jayasree Ramapurath S.
Published: April 2020

This study tests the use of a constrained nonnegative matrix factorization (NMF) algorithm to explore the comparatively new field of chemometric microscopy to support tissue diagnosis. The algorithm can extract the spectral signature and the absolute concentration map of endogenous fluorophores from wide-field microscopic images. The resultant data distinguished normal and fibrous calvarial tissues, based on the changes in their spectral signatures. The absolute concentration map of endogenous fluorophores, nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), and lipofuscin were derived from microscopic images and compared with the fluorescence from pure fluorophores. While the absolute concentration of NADH increased, the same of FAD and lipofuscin decreased from a normal to fibrous calvarial condition. An increase in the optical redox ratio, possibly due to the metabolic changes during the development of fibrosis, was observed. Differentiating tissue types using the absolute concentration map was found to be considerably more precise than that achievable with relative concentration. The quantification of fluorophores with reference to the absolute concentration map can eliminate uncertainties due to system responses or measurement details, thereby generating more biologically apposite data. Wide-field microscopy augmented with a constrained NMF algorithm could emerge as an advanced diagnostic tool, potentially heralding the emergence of chemometric microscopy.
To analyse target volume variations during SIB-IMRT of squamous cell carcinoma of uterine cervix
Authors: Shamsi Qurat-ul-Ain , Iqbal Khalid , Jabeen Shagufta , Buzdar Saeed Ahmad
Published: April 2020

Purpose:

To assess volume variations in target site due to changes in bladder filling and rectal content including air bubbles during simultaneous-integrated boost intensity-modulated radiotherapy (SIB-IMRT) of patients suffering from squamous cell carcinoma of uterine cervix.

Materials and methods:

A total of ten patients of squamous cell carcinoma of uterine cervix were enrolled in this analysis. All patients were planned to undergo SIB-IMRT using 10 MV beam. Planning target volume of the tumour (PTVtumour) and PTVnodal were prescribed with 5,040 and 4,500 cGy doses, respectively. During planning, PTVtumour V95%, PTVnodal V95% and organs at risk (OARs) (bladder, rectum, femoral heads and small bowel) volumes were measured from initial CT planning scans taken with full bladder. CT scans were acquired once in a week over a treatment period of 5·5 weeks. Intra-treatment scans with full bladder were then fused with the planning scans to determine variations in the target volume and the OAR volume. Changes in radiation dose to the PTVtumour and the PTVnodal were also assessed by comparing intra-treatment scans with the planning (first) scans.

Results:

All patients showed intra-treatment bladder volume larger than the planning bladder volume. Difference between planning bladder and intra-treatment bladder volumes ranged from 4·5 to 49%. Rectal volume varied from 17 to 60 cc. A wide variation between planning and intra-treatment air volumes was found in most of the patients. When comparing initial and inter-fraction air volumes, the maximum difference was 366·67%. Due to bladder and rectal volume variations, PTVtumour V95% and PTVnodal V95% doses did not remain constant throughout the treatment. The maximum discrepancy between intra-treatment PTVtumour dose and planning PTVtumour dose was 12·15%. The maximum difference between planning and inter-fraction PTV V95% was 48·28%. PTVnodal dose observed from scan taken in last week of treatment was 12·87% less than planning PTVnodal dose analysed from planning CT scan. Maximum difference in planning and inter-fraction PTVnodal V95% was 57·78%.

Conclusion:

Inconsistent bladder and rectal volumes had a significant impact on target volume and dosage during an entire course of SIB-IMRT. For radiotherapy of gynaecological malignancies, data on variations in PTV should be acquired on daily basis to target radiation dose to the tumour site with accuracy.
Baptists and Bootleggers in the Biodiesel Trade: EU–Biodiesel (Indonesia)
Authors: Fischer Carolyn , Meyer Timothy
Published: April 2020

EU–Biodiesel (Indonesia) is the latest in two lines of cases. On the one hand, the case offers yet another example of the Dispute Settlement Body striking down creative interpretations of antidumping rules by developed countries. Applying the Appellate Body's decision in EU–Biodiesel (Argentina), the panel found that the EU could not use antidumping duties to counteract the effects of Indonesia's export tax on palm oil. On the other hand, the decision is another chapter in the battle over renewable energy markets. Both the EU and Indonesia had intervened in their markets to promote the development of domestic biodiesel industries. The panel's decision prevents the EU from using antidumping duties to preserve market opportunities created by its Renewable Energy Directive for its domestic biodiesel producers. The EU has responded in two ways. First, through regulations that disfavor palm-based biodiesel, but not biodiesel made from from other foodstocks, such as rapeseed oil commonly produced in the EU. Second, the EU has imposed countervailing duties on Indonesian biodiesel, finding that Indonesia's export tax on crude palm oil constitutes a subsidy to Indonesian biodiesel producers. The EU's apparently inelastic demand for protection raises two questions: First, when domestic political bargains rest on both protectionist and non-protectionist motives and policies have both protectionist and non-protectonist effects, what are the welfare consequences of restraining only overt protectionism? Second, under what circumstances may regulatory approaches be even less desirable than duties for addressing combined protectionist and environmental interests, and would the WTO have the right powers to discipline them in an environmentally sound way?
A Numerical Model of CPR of Rough Surface With Discrete Scatterers for Analysis of Mini‐RF Data
Authors: Liu Niutao , Xu Feng , Jin Ya‐Qiu
Published: April 2020

Circular polarization ratio (CPR) was regarded as an important index for detecting water ice in the permanently shaded region (PSR) of the Moon poles. However, many studies have intuitively described that the double‐bounce scatte ring caused by dihedral consisting of rock facets and the lunar rough surface may yield high CPR. Under a large local incidence angle, single scattering is reduced. Double‐bounce scattering of the dihedral governs the echoes and leads to an enhanced CPR. In this paper, a numerical model of the lunar rough surface with discrete scatterers, for example, rock bodies, is developed. The bidirectional analytic ray tracing (BART) method is applied to numerically solve high‐order scattering of this surface/rocks model. The lunar surface is modeled by the Digital Elevation Model (DEM) data from Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA). This paper quantitatively analyzes how the surface topography, rocks, radar local incidence, etc, affect the CPR. It is found that at a small local incident angle, the single scattering is usually dominant and results in a small CPR. When the local incident angle becomes large, the radar wave reflected in the specular direction is more likely to be reflected again and increases the CPR.
Coupling Between E Region Quasi‐Periodic Echoes and F Region Medium‐Scale Traveling Ionospheric Disturbances at Low Latitudes
Authors: Xie Haiyong , Li Guozhu , Zhao Xiukuan , Ding Feng , Yan Chunxiao , Yang Guotao , Ning Baiqi
Published: April 2020

E region quasi‐periodic (QP) echoes from a VHF coherent backscatter radar, sporadic E (Es) layer from a digisonde, and F region medium‐scale traveling ionospheric disturbances (MSTIDs) from global navigation satellite systems receivers were simultaneously observed at low latitudes. The results on the night of 3 March 2018 show that the QP echoes in radar height‐time intensity maps were clustered into groups, coinciding with the periods of MSTIDs and strong Es layer. The MSTIDs had phase fronts elongating in the northwest‐southeast direction and propagated southwestward from middle to low latitudes. Similar to the propagation direction of MSTIDs, the low‐latitude Es layers also propagated southwestward. For the QP echoing clusters, a westward drift was seen from the radar multibeam observations. The Doppler velocities of QP echoes show beam dependence, with significantly enhanced positive values (motion away from the radar) in the westernmost beam. Based on a preliminary statistical analysis during the period March–June 2018, it was found that out of a total of 102 nights, there are 32 nights when QP echoes were generated. The simultaneous occurrences of QP echoes and MSTIDs were observed on six nights. We suggest that when the MSTIDs coming from middle latitudes approach low latitudes, the polarization electric fields associated with the MSTIDs could modulate the E region plasma instability producing QP echoes at low latitudes through the E‐F region electrodynamic coupling.
The Tectonic “Umbilical Cord” Linking India and Sri Lanka and the Tale of their Failed Rift
Authors: Ratheesh‐Kumar R. T. , Dharmapriya P. L. , Windley B. F. , Xiao W. J. , Jeevan U.
Published: April 2020

Geophysical studies of the tectonic links between Sri Lanka and India are limited, and consequent paleo‐fit configurations differ and remain uncertain. Here, we present first‐order constraints for an optimum link between Sri Lanka and southern India by using high‐resolution maps of elastic thickness (Te) and crustal thickness (Tc) derived from a flexure inversion method that based on the space‐domain convolution technique for a data window covering integral continental‐oceanic lithospheric setting. We find that the spatial variations of Te and Tc over different crustal provinces in southern India and Sri Lanka agree well with their tectonic classifications proposed by geological studies. Importantly, this study provides much‐needed confirmation of the rifting and associated lithospheric deformation along the mirrored continental margins of India and Sri Lanka and in the intervening transitional lithosphere. The two margins are marked by patterns of low Te and thinned crust, which suggests that an anticlockwise rift (eastward rift) of Sri Lanka away from India resulted in the creation of the Mannar Basin, and a secondary N‐S rifting gave rise to the Cauvery Basin. However, these developments led to a final failed rift, which we attribute to a mechanically strong continental lithospheric bond (a NW‐SE zone of high‐Te and relatively thick crust) that was present in the intervening Palk Strait. We matched the identical zones of Te variations along the two mirrored continental margins and thus obtained a coherent paleo‐fit configuration, and a step‐by‐step evolution of these margins was constructed by using magnetic anomaly‐based paleo‐fit reconstruction models.
Volume Characteristics of Landslides Triggered by the MW 7.8 2016 Kaikōura Earthquake, New Zealand, Derived From Digital Surface Difference Modeling
Authors: Massey C. I. , Townsend D. , Jones K. , Lukovic B. , Rhoades D. , Morgenstern R. , Rosser B. , Ries W. , Howarth J. , Hamling I. , Petley D. , Clark M. , Wartman J. , Litchfield N. , Olsen M.
Published: April 2020

We use a mapped landslide inventory coupled with a 2‐m resolution vertical difference model covering an area of 6,875 km2 to accurately constrain landslide volume‐area relationships. We use the difference model to calculate the source volumes for landslides triggered by the MW 7.8 Kaikōura, New Zealand, earthquake of 14 November 2016. Of the 29,519 mapped landslides in the inventory, 28,394 are within the analysis area, and of these, we have calculated the volume of 17,256 source areas that are ≥90% free of debris. Of the 28,394 landslides, about 80% are classified as soil or rock avalanches and the remainder as mainly translational slides. Our results show that both the soil avalanches and the rock avalanches, ignoring their source geology, have area to volume power‐law scaling exponents (γ) of 0.921 to 1.060 and 1.040 to 1.138, respectively. These are lower than the γ values of 1.1–1.3 (for soil) and 1.3–1.6 (for rock) reported in the literature for undifferentiated landslide types. They are, however, similar to those γ values estimated from other coseismic landslide inventories. In contrast, for 50 selected rotational, translational (planar slide surfaces), or compound slides, where much of the debris remains in the source area, we found γ values range between 1.46 and 1.47, indicating that their slide surfaces were considerably deeper than those landslides classified as avalanches. This study, like previous studies on coseismic landslides, shows that soil and rock avalanches (disrupted landslides) are the dominant landslide type triggered by earthquakes and that they tend to be shallow.
An Eigenmode Correlation‐Based Algorithm for Approaching Antenna Optimal Currents With Multiple Feeds
Authors: Zhang Wei‐Quan , Zhang Guo‐Yang , Wang Bing‐Zhong , Xiong Jiang
Published: April 2020

A feeding algorithm has been proposed for the excitation of the optimal electric current of Rayleigh quotient form optimization problems. Modal weighting coefficients of the corresponding generalized eigenvalue problem are calculated to form the correlation information between the desired and all other unwanted modes. Based on this information, multiple feeds are arranged to approximate the desired current distributions. The eigencurrent distribution is also utilized for some shape modification to the radiator for a possible feed number reduction. Three canonical optimization problems for electrically small antennas, minimum Q, maximum G/Q, and maximum G are studied and discussed. Several numerical examples with a certain arbitrary shape and electrical size are given. With the proposed feeding algorithm, calculated and simulated current distributions and performance indices are close to the theoretical optimum solution. Finally, a practical feeding network design for a classic characteristic mode problem is shown as a validation.
Estimation of Direct and Indirect Economic Losses Caused by a Flood With Long‐Lasting Inundation: Application to the 2011 Thailand Flood
Authors: Tanoue M. , Taguchi R. , Nakata S. , Watanabe S. , Fujimori S. , Hirabayashi Y.
Published: April 2020

River floods are common natural disasters that cause serious economic damage worldwide. In addition to direct economic damage, such as the destruction of physical assets, floods with long‐lasting inundation cause direct and indirect economic losses within and outside the affected area. Direct economic losses include loss of opportunity, due to interruption of business activities, and the costs associated with emergency measures such as cleaning, while indirect economic losses affect sectors within the trade and supply network. Few studies have explicitly estimated direct and indirect economic losses in several sectors, due to the difficulty of modeling inundation depth and period at finer scales. Here we developed a global modeling framework to estimate the direct and indirect economic losses associated with floods using a computable general equilibrium model and a global river and inundation model, which can simulate the flood extent, depth, and period. Application of the method to the 2011 Thailand flood demonstrated that the estimated economic losses due to business interruption in the industry and service sectors totaled $14.7 billion, which was about two thirds of the estimated direct economic damage caused by the flood ($22.0 billion). The estimated indirect economic losses reduced the gross domestic product of Thailand by 4.81% in 2011, without considering transboundary effects, and will cause more than 0.5% reduction in gross domestic product even in 2030, resulting in $55.3 billion of total losses from 2011 to 2030. Comprehensive estimation of direct and indirect economic losses facilitates understanding of various types of flood‐related economic risks during and after a flood.
Dynamics of Viscous Fingering in Porous Media in the Presence of In Situ Formed Precipitates and Their Subsequent Deposition
Authors: Sabet Nasser , Hassanzadeh Hassan , Abedi Jalal
Published: April 2020

Understanding the dynamics of miscible viscous fingering is of paramount importance in a wide range of applications, from groundwater hydrology to enhanced oil recovery. In this work, we investigate the effect of precipitation and deposition of an initially dissolved component and the subsequent porosity and permeability variations on miscible viscous fingering in porous media. The commonly used stream function‐vorticity formulation does not allow for nonsolenoidality of the velocity vector, which is the case when the porosity field varies with time. This is why we develop a velocity‐vorticity formulation, making no further simplifications on the flow field. For numerical simulations, the governing equations are solved using the hybridization of pseudospectral and compact finite difference methods, and the time stepping is carried out through high‐order semi‐implicit schemes. Using our methodology, we tackle the problem of precipitation of an initially dissolved component through an infinitely fast and reversible reaction. It is found that the deposition of the formed precipitates in porous media results in more severe interfacial instabilities, the effect of which is attenuated as the viscosity ratio between the displacing and resident fluids increases. In addition, our results show that the formed precipitates are mostly concentrated around the interface where the two fluids actively mix. We also characterize the alterations of the local and global permeability fields, and interestingly, we find that the ultimate value of the overall permeability of the porous media scales linearly with the log‐viscosity ratio at any fixed deposition rate. It is worth mentioning that, without loss of generality, the developed methodology and analysis in this study are applicable to other forms of precipitation reactions (e.g., finite rate and irreversible) in porous media.
The Balance and Abnormal Increase of Global Ocean Mass Change From Land Using GRACE
Authors: Jin Taoyong , Li Xiaolong , Shum C. K. , Ding Hao , Xu Xinyu
Published: April 2020

Global ocean mass (GOM) change, which is mainly influenced by water outflow from land, has been identified as one of the important contributors to present‐day sea level rise. Here, we delineated GOM change by dividing the land into five parts, which are exorheic river basins, endorheic basins, polar ice sheets, and land glaciers and ice caps, by the Gravity Recovery and Climate Experiment mass concentration solutions, 2002–2017. We estimated their total contribution to GOM change to be 568.92 ± 21.43 GT•yr−1, which is statistically congruent with the Gravity Recovery and Climate Experiment estimated GOM change (579.46 ± 46.62 GT•yr−1). The melting of Earth's ice reservoirs is the dominant contribution in the whole period. However, an abnormal increase is found in the trend of GOM change with an amplitude of approximately 100% since August 2008. Further finding reveals that melting of Antarctica Ice Sheets are increasing fast and significantly dominates among other geophysical contributions to the abnormal increase at 34.28%, following with the water storage change of exorheic river basins at 28.71% and the melting of Greenland Ice Sheets at 22.76%, which is postulated to be resulting from intensified ice wastages and precipitation during the last decade.
Retrieval of Vertical Profile of Cirrus Cloud Effective Particle Size Using Reflected Line Spectra in 1.38 μm Band
Authors: Gu Yu , Takano Yoshi , Liou Kuo‐Nan
Published: April 2020

This paper presents a new retrieval method for inferring the vertical profile of cirrus cloud effective particle size by using solar reflected line spectra in the 1.38‐μm band. The retrieval method is based on the maximum‐photon penetration principle coupled with the constrained linear inversion. This approach takes advantage of the vertical stratification of cirrus cloud effective particle size as well as absorption lines of water vapor of different intensity, which contain rich information on the vertical structure of cloud particle size. Reflected radiances at different wavenumbers provide the effective‐size information at different heights within cirrus associated with photon different penetration depths. Assuming a vertical profile of effective size monotonically decreasing toward cloud top and using results based on “exact” radiative transfer computations, we perform retrieval of the effective size for a number of model cirrus to check for algorithm accuracy. The retrieved profile of effective size is close to the model profile for cirrus optical depth less than about eight with an uncertainty range of 2.2–4.2 μm. In addition, we further carry out a sensitivity study involving the retrieved effective size in connection with different water vapor profiles and demonstrate that the difference from the model is only several percent except for the cloud top if an appropriate wavenumber set is selected. The results from this study suggest that the present method can be applied to realistic remote sensing of the vertical profile of cirrus cloud particle size.
Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection Dynamics in Jupiter's Io Torus Regions
Authors: Mauk B. H. , Clark G. , Allegrini F. , Bagenal F. , Bolton S. J. , Connerney J. E. P. , Haggerty D. K. , Kollmann P. , Mitchell D. G. , Paranicas C. P. , Rymer A. M.
Published: April 2020

In planetary magnetospheres, singly charged energetic particles, trapped by the planet's magnetic field, can steal electrons from cold gas atoms and become neutralized. These now energetic neutral atoms (ENAs), no longer confined by the magnetic field, can travel out of the system similar to photons leaving a hot oven. ENAs have been used to image magnetospheric processes at Earth, Jupiter, and Saturn. At Jupiter, the opportunities to image the magnetosphere have been limited and always from the perspective of the near‐equatorial plane at distance >139 RJ. The polar‐orbiting Juno mission carries the Jupiter Energetic particle Detector Instrument that is serendipitously sensitive to ENAs with energies >50 keV, provided that there are no charged particles in the environment to mask their presence. Here we report on the first ENA observations of Jupiter's magnetosphere from a nonequatorial perspective. In this brief report we concentrate on emissions seen during Perijove 22 (PJ22) during very active conditions and compare them with emissions during the inactive Perijove 23 (PJ23). We observe, and discriminate between, distinct ENA signatures from the neutral gases occupying the orbit of Io (away from Io itself), the orbit of Europa (away from Europa), and from Jupiter itself. Strong ENA emissions from Io's orbit during PJ22 are associated with energetic particle injections observed near Io's orbit several hours earlier. Some injections occurred planetward of Io's L‐shell (magnetic position), somewhat of a surprise given that injections are thought to be driven by outward transport of plasmas generated by Io.
Persistent global marine euxinia in the early Silurian
Authors: Stockey Richard G. , Cole Devon B. , Planavsky Noah J. , Loydell David K. , Frýda Jiří , Sperling Erik A.
Published: April 2020

The second pulse of the Late Ordovician mass extinction occurred around the Hirnantian-Rhuddanian boundary (~444 Ma) and has been correlated with expanded marine anoxia lasting into the earliest Silurian. Characterization of the Hirnantian ocean anoxic event has focused on the onset of anoxia, with global reconstructions based on carbonate δ238U modeling. However, there have been limited attempts to quantify uncertainty in metal isotope mass balance approaches. Here, we probabilistically evaluate coupled metal isotopes and sedimentary archives to increase constraint. We present iron speciation, metal concentration, δ98Mo and δ238U measurements of Rhuddanian black shales from the Murzuq Basin, Libya. We evaluate these data (and published carbonate δ238U data) with a coupled stochastic mass balance model. Combined statistical analysis of metal isotopes and sedimentary sinks provides uncertainty-bounded constraints on the intensity of Hirnantian-Rhuddanian euxinia. This work extends the duration of anoxia to >3 Myrs – notably longer than well-studied Mesozoic ocean anoxic events.
Pan-active imidazolopiperazine antimalarials target the Plasmodium falciparum intracellular secretory pathway
Authors: LaMonte Gregory M. , Rocamora Frances , Marapana Danushka S. , Gnädig Nina F. , Ottilie Sabine , Luth Madeline R. , Worgall Tilla S. , Goldgof Gregory M. , Mohunlal Roxanne , Santha Kumar T. R. , Thompson Jennifer K. , Vigil Edgar , Yang Jennifer , Hutson Dylan , Johnson Trevor , Huang Jianbo , Williams Roy M. , Zou Bing Yu , Cheung Andrea L. , Kumar Prianka , Egan Timothy J. , Lee Marcus C. S. , Siegel Dionicio , Cowman Alan F. , Fidock David A. , Winzeler Elizabeth A.
Published: April 2020

A promising new compound class for treating human malaria is the imidazolopiperazines (IZP) class. IZP compounds KAF156 (Ganaplacide) and GNF179 are effective against Plasmodium symptomatic asexual blood-stage infections, and are able to prevent transmission and block infection in animal models. But despite the identification of resistance mechanisms in P. falciparum, the mode of action of IZPs remains unknown. To investigate, we here combine in vitro evolution and genome analysis in Saccharomyces cerevisiae with molecular, metabolomic, and chemogenomic methods in P. falciparum. Our findings reveal that IZP-resistant S. cerevisiae clones carry mutations in genes involved in Endoplasmic Reticulum (ER)-based lipid homeostasis and autophagy. In Plasmodium, IZPs inhibit protein trafficking, block the establishment of new permeation pathways, and cause ER expansion. Our data highlight a mechanism for blocking parasite development that is distinct from those of standard compounds used to treat malaria, and demonstrate the potential of IZPs for studying ER-dependent protein processing.
Irreversible accumulated SERS behavior of the molecule-linked silver and silver-doped titanium dioxide hybrid system
Authors: Zhou Lu , Zhou Jun , Lai Wei , Yang Xudong , Meng Jie , Su Liangbi , Gu Chenjie , Jiang Tao , Pun Edwin Yue Bun , Shao Liyang , Petti Lucia , Sun Xiao Wei , Jia Zhenghong , Li Qunxiang , Han Jiaguang , Mormile Pasquale
Published: April 2020

In recent years, surface-enhanced Raman scattering (SERS) of a molecule/metal–semiconductor hybrid system has attracted considerable interest and regarded as the synergetic contribution of the electromagnetic and chemical enhancements from the incorporation of noble metal into semiconductor nanomaterials. However, the underlying mechanism is still to be revealed in detail. Herein, we report an irreversible accumulated SERS behavior induced by near-infrared (NIR) light irradiating on a 4-mercaptobenzoic acid linked with silver and silver-doped titanium dioxide (4MBA/Ag/Ag-doped TiO2) hybrid system. With increasing irradiation time, the SERS intensity of 4MBA shows an irreversible exponential increase, and the Raman signal of the Ag/Ag-doped TiO2 substrate displays an exponential decrease. A microscopic understanding of the time-dependent SERS behavior is derived based on the microanalysis of the Ag/Ag-doped TiO2 nanostructure and the molecular dynamics, which is attributed to three factors: (1) higher crystallinity of Ag/Ag-doped TiO2 substrate; (2) photo-induced charge transfer; (3) charge-induced molecular reorientation.
Transposable elements contribute to cell and species-specific chromatin looping and gene regulation in mammalian genomes
Authors: Diehl Adam G. , Ouyang Ningxin , Boyle Alan P.
Published: April 2020

Chromatin looping is important for gene regulation, and studies of 3D chromatin structure across species and cell types have improved our understanding of the principles governing chromatin looping. However, 3D genome evolution and its relationship with natural selection remains largely unexplored. In mammals, the CTCF protein defines the boundaries of most chromatin loops, and variations in CTCF occupancy are associated with looping divergence. While many CTCF binding sites fall within transposable elements (TEs), their contribution to 3D chromatin structural evolution is unknown. Here we report the relative contributions of TE-driven CTCF binding site expansions to conserved and divergent chromatin looping in human and mouse. We demonstrate that TE-derived CTCF binding divergence may explain a large fraction of variable loops. These variable loops contribute significantly to corresponding gene expression variability across cells and species, possibly by refining sub-TAD-scale loop contacts responsible for cell-type-specific enhancer-promoter interactions.
Interplay between midbrain and dorsal anterior cingulate regions arbitrates lingering reward effects on memory encoding
Authors: Aberg Kristoffer Carl , Kramer Emily Elizabeth , Schwartz Sophie
Published: April 2020

Rewarding events enhance memory encoding via dopaminergic influences on hippocampal plasticity. Phasic dopamine release depends on immediate reward magnitude, but presumably also on tonic dopamine levels, which may vary as a function of the average accumulation of reward over time. Using model-based fMRI in combination with a novel associative memory task, we show that immediate reward magnitude exerts a monotonically increasing influence on the nucleus accumbens, ventral tegmental area (VTA), and hippocampal activity during encoding, and enhances memory. By contrast, average reward levels modulate feedback-related responses in the VTA and hippocampus in a non-linear (inverted U-shape) fashion, with similar effects on memory performance. Additionally, the dorsal anterior cingulate cortex (dACC) monotonically tracks average reward levels, while VTA-dACC functional connectivity is non-linearly modulated (inverted U-shape) by average reward. We propose that the dACC computes the net behavioral impact of average reward and relays this information to memory circuitry via the VTA.
Re-definition of claudin-low as a breast cancer phenotype
Authors: Fougner Christian , Bergholtz Helga , Norum Jens Henrik , Sørlie Therese
Published: April 2020

The claudin-low breast cancer subtype is defined by gene expression characteristics and encompasses a remarkably diverse range of breast tumors. Here, we investigate genomic, transcriptomic, and clinical features of claudin-low breast tumors. We show that claudin-low is not simply a subtype analogous to the intrinsic subtypes (basal-like, HER2-enriched, luminal A, luminal B and normal-like) as previously portrayed, but is a complex additional phenotype which may permeate breast tumors of various intrinsic subtypes. Claudin-low tumors are distinguished by low genomic instability, mutational burden and proliferation levels, and high levels of immune and stromal cell infiltration. In other aspects, claudin-low tumors reflect characteristics of their intrinsic subtype. Finally, we explore an alternative method for identifying claudin-low tumors and thereby uncover potential weaknesses in the established claudin-low classifier. In sum, these findings elucidate the heterogeneity in claudin-low breast tumors, and substantiate a re-definition of claudin-low as a cancer phenotype.
Transient stripping of subducting slabs controls periodic forearc uplift
Authors: Menant Armel , Angiboust Samuel , Gerya Taras , Lacassin Robin , Simoes Martine , Grandin Raphael
Published: April 2020

Topography in forearc regions reflects tectonic processes along the subduction interface, from seismic cycle-related transients to long-term competition between accretion and erosion. Yet, no consensus exists about the topography drivers, especially as the contribution of deep accretion remains poorly constrained. Here, we use thermo-mechanical simulations to show that transient slab-top stripping events at the base of the forearc crust control uplift-then-subsidence sequences. This 100s-m-high topographic signal with a Myr-long periodicity, mostly inaccessible to geodetic and geomorphological records, reflects the nature and influx rate of material involved in the accretion process. The protracted succession of stripping events eventually results in the pulsing rise of a large, positive coastal topography. Trench-parallel alternation of forearc highs and depressions along active margins worldwide may reflect temporal snapshots of different stages of these surface oscillations, implying that the 3D shape of topography enables tracking deep accretion and associated plate-interface frictional properties in space and time.
Modeling germline mutations in pineoblastoma uncovers lysosome disruption-based therapy
Authors: Chung Philip E. D. , Gendoo Deena M. A. , Ghanbari-Azarnier Ronak , Liu Jeff C. , Jiang Zhe , Tsui Jennifer , Wang Dong-Yu , Xiao Xiao , Li Bryan , Dubuc Adrian , Shih David , Remke Marc , Ho Ben , Garzia Livia , Ben-David Yaacov , Kang Seok-Gu , Croul Sidney , Haibe-Kains Benjamin , Huang Annie , Taylor Michael D. , Zacksenhaus Eldad
Published: April 2020

Pineoblastoma is a rare pediatric cancer induced by germline mutations in the tumor suppressors RB1 or DICER1. Presence of leptomeningeal metastases is indicative of poor prognosis. Here we report that inactivation of Rb plus p53 via a WAP-Cre transgene, commonly used to target the mammary gland during pregnancy, induces metastatic pineoblastoma resembling the human disease with 100% penetrance. A stabilizing mutation rather than deletion of p53 accelerates metastatic dissemination. Deletion of Dicer1 plus p53 via WAP-Cre also predisposes to pineoblastoma, albeit with lower penetrance. In silico analysis predicts tricyclic antidepressants such as nortriptyline as potential therapeutics for both pineoblastoma models. Nortriptyline disrupts the lysosome, leading to accumulation of non-functional autophagosome, cathepsin B release and pineoblastoma cell death. Nortriptyline further synergizes with the antineoplastic drug gemcitabine to effectively suppress pineoblastoma in our preclinical models, offering new modality for this lethal childhood malignancy.
P2X7 receptor inhibition ameliorates dendritic spine pathology and social behavioral deficits in Rett syndrome mice
Authors: Garré Juan Mauricio , Silva Hernandez Moura , Lafaille Juan J. , Yang Guang
Published: April 2020

Dysregulated immunity has been implicated in the pathogenesis of neurodevelopmental disorders but its contribution to synaptic and behavioral deficits in Rett syndrome (RTT) remains unknown. P2X7 receptors (P2X7Rs) are unique purinergic receptors with pro-inflammatory functions. Here, we report in a MECP2-deficient mouse model of RTT that the border of the cerebral cortex exhibits increased number of inflammatory myeloid cells expressing cell-surface P2X7Rs. Total knockout of P2X7Rs in MECP2 deficient mice decreases the number of inflammatory myeloid cells, restores cortical dendritic spine dynamics, and improves the animals’ neurological function and social behavior. Furthermore, either genetic depletion of P2X7Rs in bone-marrow derived leukocytes or pharmacological block of P2X7Rs primarily outside of the central nervous system parenchyma, recapitulates the beneficial effects of total P2X7R depletion on the social behavior. Together, our results highlight the pathophysiological roles of P2X7Rs in a mouse model of RTT.
Chromatin architecture reorganization in murine somatic cell nuclear transfer embryos
Authors: Chen Mo , Zhu Qianshu , Li Chong , Kou Xiaochen , Zhao Yanhong , Li Yanhe , Xu Ruimin , Yang Lei , Yang Lingyue , Gu Liang , Wang Hong , Liu Xiaoyu , Jiang Cizhong , Gao Shaorong
Published: April 2020

The oocyte cytoplasm can reprogram the somatic cell nucleus into a totipotent state, but with low efficiency. The spatiotemporal chromatin organization of somatic cell nuclear transfer (SCNT) embryos remains elusive. Here, we examine higher order chromatin structures of mouse SCNT embryos using a low-input Hi-C method. We find that donor cell chromatin transforms to the metaphase state rapidly after SCNT along with the dissolution of typical 3D chromatin structure. Intriguingly, the genome undergoes a mitotic metaphase-like to meiosis metaphase II-like transition following activation. Subsequently, weak chromatin compartments and topologically associating domains (TADs) emerge following metaphase exit. TADs are further removed until the 2-cell stage before being progressively reestablished. Obvious defects including stronger TAD boundaries, aberrant super-enhancer and promoter interactions are found in SCNT embryos. These defects are partially caused by inherited H3K9me3, and can be rescued by Kdm4d overexpression. These observations provide insight into chromatin architecture reorganization during SCNT embryo development.
Microbiota-induced tissue signals regulate ILC3-mediated antigen presentation
Authors: Lehmann Frank Michael , von Burg Nicole , Ivanek Robert , Teufel Claudia , Horvath Edit , Peter Annick , Turchinovich Gleb , Staehli Daniel , Eichlisberger Tobias , Gomez de Agüero Mercedes , Coto-Llerena Mairene , Prchal-Murphy Michaela , Sexl Veronika , Bentires-Alj Mohamed , Mueller Christoph , Finke Daniela
Published: April 2020

Although group 3 innate lymphoid cells (ILC3s) are efficient inducers of T cell responses in the spleen, they fail to induce CD4+T cell proliferation in the gut. The signals regulating ILC3-T cell responses remain unknown. Here, we show that transcripts associated with MHC II antigen presentation are down-modulated in intestinal natural cytotoxicity receptor (NCR)−ILC3s. Further data implicate microbiota-induced IL-23 as a crucial signal for reversible silencing of MHC II in ILC3s, thereby reducing the capacity of ILC3s to present antigen to T cells in the intestinal mucosa. Moreover, IL-23-mediated MHC II suppression is dependent on mTORC1 and STAT3 phosphorylation in NCR−ILC3s. By contrast, splenic interferon-γ induces MHC II expression and CD4+T cell stimulation by NCR−ILC3s. Our results thus identify biological circuits for tissue-specific regulation of ILC3-dependent T cell responses. These pathways may have implications for inducing or silencing T cell responses in human diseases.
Phase-resolved Higgs response in superconducting cuprates
Authors: Chu Hao , Kim Min-Jae , Katsumi Kota , Kovalev Sergey , Dawson Robert David , Schwarz Lukas , Yoshikawa Naotaka , Kim Gideok , Putzky Daniel , Li Zhi Zhong , Raffy Hélène , Germanskiy Semyon , Deinert Jan-Christoph , Awari Nilesh , Ilyakov Igor , Green Bertram , Chen Min , Bawatna Mohammed , Cristiani Georg , Logvenov Gennady , Gallais Yann , Boris Alexander V. , Keimer Bernhard , Schnyder Andreas P. , Manske Dirk , Gensch Michael , Wang Zhe , Shimano Ryo , Kaiser Stefan
Published: April 2020

In high-energy physics, the Higgs field couples to gauge bosons and fermions and gives mass to their elementary excitations. Experimentally, such couplings can be inferred from the decay product of the Higgs boson, i.e., the scalar (amplitude) excitation of the Higgs field. In superconductors, Cooper pairs bear a close analogy to the Higgs field. Interaction between the Cooper pairs and other degrees of freedom provides dissipation channels for the amplitude mode, which may reveal important information about the microscopic pairing mechanism. To this end, we investigate the Higgs (amplitude) mode of several cuprate thin films using phase-resolved terahertz third harmonic generation (THG). In addition to the heavily damped Higgs mode itself, we observe a universal jump in the phase of the driven Higgs oscillation as well as a non-vanishing THG above Tc. These findings indicate coupling of the Higgs mode to other collective modes and potentially a nonzero pairing amplitude above Tc.
CdbA is a DNA-binding protein and c-di-GMP receptor important for nucleoid organization and segregation in Myxococcus xanthus
Authors: Skotnicka Dorota , Steinchen Wieland , Szadkowski Dobromir , Cadby Ian T. , Lovering Andrew L. , Bange Gert , Søgaard-Andersen Lotte
Published: April 2020

Cyclic di-GMP (c-di-GMP) is a second messenger that modulates multiple responses to environmental and cellular signals in bacteria. Here we identify CdbA, a DNA-binding protein of the ribbon-helix-helix family that binds c-di-GMP in Myxococcus xanthus. CdbA is essential for viability, and its depletion causes defects in chromosome organization and segregation leading to a block in cell division. The protein binds to the M. xanthus genome at multiple sites, with moderate sequence specificity; however, its depletion causes only modest changes in transcription. The interactions of CdbA with c-di-GMP and DNA appear to be mutually exclusive and residue substitutions in CdbA regions important for c-di-GMP binding abolish binding to both c-di-GMP and DNA, rendering these protein variants non-functional in vivo. We propose that CdbA acts as a nucleoid-associated protein that contributes to chromosome organization and is modulated by c-di-GMP, thus revealing a link between c-di-GMP signaling and chromosome biology.