bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification and kinematics of the Planpincieux Glacier break-offs using photographic time-lapse analysis
Authors: Giordan Daniele , Dematteis Niccolò , Allasia Paolo , Motta Elena
Published: January 2020

Herein, we present results obtained from time-lapse imagery acquired by a digital single-lens reflex camera during 2014–18 used to monitor the Planpincieux Glacier on the Italian side of the Grandes Jorasses (Mont Blanc massif). We processed the images using image cross-correlation to measure the surface kinematics of the most active lobe of the glacier that presents a high velocity and frequent ice detachments. During the monitoring, we observed two or three periods of sharp acceleration per year that culminated with large break-offs followed by analogous decelerations. Overall, we registered more than 350 failures with a volume >100 m3, of which, 14 events had volumes larger than 10 000 m3. The study identified a monotonic positive relationship between the velocity and failure volume that may be used to estimate the volume of the collapses before an event. We identified the thresholds of velocity and acceleration that characterise the activation of the speed-up periods. The study allowed the characterisation of three different instability processes that lead to the break-off of ice chunks from the glacier terminus: (i) disaggregation, (ii) slab fracture and (iii) water tunnelling failure which can be differentiated based on the rheology, the volume involved and the trigger process.
Variation in the yak lipin-1 gene and its association with milk traits
Authors: Wang Xin , Zhou Huitong , Hickford Jon G. H. , Li Shaobin , Wang Jiqing , Liu Xiu , Hu Jiang , Luo Yuzhu
Published: January 2020

The aim of this research was to identify variation in the yak lipin-1 gene (LPIN1) and determine whether this variation affects milk traits. PCR-single stranded conformational polymorphism (PCR-SSCP) analysis was used to detect variation in the 5′ untranslated region of LPIN1 in 500 yaks from four populations: Tianzhu white yaks, Qinghai yaks, wild × domestic-cross yaks and Gannan yaks. Four unique PCR-SSCP patterns, representing four different DNA sequence variants (named A, B, C and D), were observed. These contained six single nucleotide polymorphisms. Female Gannan yaks with BC genotype produced milk with a higher fat content (P < 0.001) and total milk solids (P < 0.001), than those with the AA, AB and BB genotypes. These results would suggest that LPIN1 is having an effect on yak milk fat synthesis.
Improvement of Single-Frequency GPS Positioning Performance Based on EGNOS Corrections in Algeria
Authors: Tabti Lahouaria , Kahlouche Salem , Benadda Belkacem , Beldjilali Bilal
Published: January 2020

The main objective of the European Geostationary Navigation Overlay System (EGNOS) is to improve the positioning accuracy by correcting several error sources affecting the Global Positioning System (GPS) and to provide integrity information to GPS signals for users in real time. This research presents analysis used to investigate improvement in the performance of single-frequency GPS positioning using EGNOS corrections in Algeria. In this study, we performed position measurements with two calculation approaches, the first based on GPS single-point positioning and the second using EGNOS differential corrections. Positioning accuracy was determined by comparison with the known precise coordinates of the sites; and then the improved ionospheric correction using EGNOS was investigated. The results revealed that GPS + EGNOS performance was significantly improved compared with GPS alone, when measurements of horizontal and vertical accuracy were taken into account, and that the EGNOS corrections improved east and north components slightly, and the up component significantly.
HOPF BIFURCATION FROM NEW-KEYNESIAN TAYLOR RULE TO RAMSEY OPTIMAL POLICY
Authors: Chatelain Jean-Bernard , Ralf Kirsten
Published: January 2020

This paper compares different implementations of monetary policy in a new-Keynesian setting. We can show that a shift from Ramsey optimal policy under short-term commitment (based on a negative feedback mechanism) to a Taylor rule (based on a positive feedback mechanism) corresponds to a Hopf bifurcation with opposite policy advice and a change of the dynamic properties. This bifurcation occurs because of the ad hoc assumption that interest rate is a forward-looking variable when policy targets (inflation and output gap) are forward-looking variables in the new-Keynesian theory.
Increase of breast-feeding in the past decade in Greece, but still low uptake: cross-sectional studies in 2007 and 2017
Authors: Iliodromiti Zoi , Zografaki Irini , Papamichail Dimitris , Stavrou Theodora , Gaki Eleni , Ekizoglou Chryssa , Nteka Eleni , Mavrika Panagiota , Zidropoulos Spilios , Panagiotopoulos Takis , Antoniadou Ioanna
Published: January 2020

Objective:

To estimate breast-feeding prevalence in Greece in 2007 and 2017, compare breast-feeding indicators and maternity hospital practices between these years, and investigate breast-feeding determinants.

Design:

Two national cross-sectional studies (2007 and 2017) using systematic cluster sampling of babies with the same sampling design, data collection and analysis methodology.

Setting:

Telephone interview with babies’ mothers or fathers.

Participants:

Representative sample of infants who participated in the national neonatal screening programme (n 549 in 2017, n 586 in 2007).

Results:

We found that breast-feeding indicators were higher in 2017 compared with 10 years before. In 2017, 94 % of mothers initiated breast-feeding. Breast-feeding rates were 80, 56 and 45 % by the end of the 1st, 4th and 6th completed month of age, respectively. At the same ages, 40, 25 and <1 % of babies, respectively, were exclusively breast-feeding. We also found early introduction of solid foods (after the 4th month of age). Maternity hospital practices favouring breast-feeding were more prevalent in 2017, but still suboptimal (63 % experienced rooming-in; 51 % experienced skin-to-skin contact in the first hour after birth; 19 % received free sample of infant formula on discharge).

Conclusions:

We observed an increasing trend in all breast-feeding indicators in the past decade in Greece, but breast-feeding rates – particularly rates of exclusive breast-feeding – remain low. Systematic public health initiatives targeted to health professionals and mothers are needed in order to change the prevailing baby feeding ‘culture’ and successfully implement the WHO recommendations for exclusive breast-feeding during the first 6 months of life.
An Open-Cell Environmental Transmission Electron Microscopy Technique for In Situ Characterization of Samples in Aqueous Liquid Solutions
Authors: Levin Barnaby D.A. , Haiber Diane , Liu Qianlang , Crozier Peter A.
Published: January 2020

The desire to image specimens in liquids has led to the development of open-cell and closed-cell techniques in transmission electron microscopy (TEM). The closed-cell approach is currently more common in TEM and has yielded new insights into a number of biological and materials processes in liquid environments. The open-cell approach, which requires an environmental TEM (ETEM), is technically challenging but may be advantageous in certain circumstances due to fewer restrictions on specimen and detector geometry. Here, we demonstrate a novel approach to open-cell liquid TEM, in which we use salt particles to facilitate the in situ formation of droplets of aqueous solution that envelope specimen particles coloaded with the salt. This is achieved by controlling sample temperature between 1 and 10°C and introducing water vapor to the ETEM chamber above the critical pressure for the formation of liquid water on the salt particles. Our use of in situ hydration enables specimens to be loaded into a microscope in a dry state using standard 3 mm TEM grids, allowing specimens to be prepared using trivial sample preparation techniques. Our future aim will be to combine this technique with an in situ light source to study photocorrosion in aqueous environments.
Comparison of conventional and hypofractionated radiation after mastectomy in locally advanced breast cancer: a prospective randomised study on dosimetric evaluation and treatment outcome
Authors: Maiti Sumana , Meyur Suman , Mandal Bidhan Chandra , Shenoi Lekshmi R , Biswas Susmita , Basu Siddhartha
Published: January 2020

Background:

Although hypofractionated radiotherapy has been standardised in early breast cancer, even in post-mastectomy no such consensus has been developed for locally advanced breast cancer (LABC), probably due to complex planning and field matching. This study is directed towards dosimetric evaluation and comparison of toxicity, response and disease-free survival (DFS) comparison between hypofractionation and conventional radiotherapy in post-mastectomy LABC.

Methodology:

In total, 222 female breast cancer patients were randomly assigned to be treated with either hypofractionated radiotherapy (n= 120) delivering 40 Gy in 15 fractions over 3 weeks or conventional radiotherapy (n= 102) with 50 Gy in 25 fractions over 5 weeks after modified radical mastectomy (MRM) along with neoadjuvant and/or adjuvant chemotherapy. All patients were planned with treatment planning software and assessed regularly during and after treatment.

Results:

Median follow-up period was 178 weeks in conventional arm (CRA) and 182 weeks in hypofractionation arm (HFA). There exists a dosimetric difference between the two arms of treatment, in spite of similar dose coverage [planning treatment volume (PTV) D90 92·04% in CRA versus 92·5% in HFA;p= 0·49], average dose in HFA is less than that of CRA (p< 0·001); so is the maximum clinical target volume (CTV) dose (p< 0·001). Similarly, average lung dose in HFA arm is significantly lower than CRA (9·9 versus 10·84;p= 0·06), but the V20Gyof lung and V30Gyof heart had no difference. The toxicity of radiation was comparable with similar mean time to produce toxicity [CRA: 7 W, HFA: 10 W; hazard ratio 0·64, 95% confidence interval (CI) = 0·28–1·45]. Three-year recurrence event was alike in two arms (CRA: 4·9%, HFA: 5·8%;p= 0·76). Mean DFS in CRA is 230 weeks and that of HFA is 235 weeks with hazard ratio 1·01 (95% CI = 0·32–3·19;p= 0·987).

Conclusion:

Though biologically effective dose (BED) in hypofractionation is lesser than that of conventional fractionation, there are indistinguishable toxicity, locoregional recurrence, distant failure rate and DFS between the two modalities.
Seasonal and Spatial Features of Barotropic and Baroclinic Tides in the Northwestern South China Sea
Authors: Yan Tong , Qi Yiquan , Jing Zhiyou , Cai Shuqun
Published: January 2020

Seven seasonal moorings distributed over the shelf and slope east of Hainan Island and south of western Guangdong Province are used to investigate the seasonal characteristics of barotropic and baroclinic tides in the northwestern South China Sea (NWSCS). The barotropic K1 current intensified during summer over the shelf sites. The diurnal baroclinic tides are much more prominent than the semidiurnal tides at each mooring site. Over the continental shelf, accompanied by large phase speeds and wavelengths, baroclinic tides are significantly enhanced in summer whereas they decrease to minimum values in winter when the water column is vertically well mixed, suggesting the key role of seasonal stratification in modulating the seasonal variation of baroclinic tide. To aid in elucidating these observations, a circulation‐tide coupled model covering the whole South China Sea (SCS) is set up for baroclinic tidal energetics in the NWSCS. Comparisons with moorings, tidal gauges, altimeters, and so on show that the model reasonably predicts the barotropic and baroclinic tides and seasonal upper circulations in the SCS and NWSCS. The model results present significant summer intensification of barotropic K1 energy in the NWSCS, which is in accordance with the observed summer‐enhanced barotropic K1 current. Strong baroclinic tides are reproduced over the summer shelf, which is related to intense stratification. The slope south of Hainan Island is a major local generation source for diurnal baroclinic tides that radiate southeastward approximately 500 km away. Both the Xisha Islands and Shenhu‐Yitong shoals act as baroclinic tidal energy sink subregions.
Carbon Deposition and Burial in Estuarine Sediments of the Contiguous United States
Authors: Hutchings J. A. , Bianchi T. S. , Najjar R. G. , Herrmann M. , Kemp W. M. , Hinson A. L. , Feagin R. A.
Published: January 2020

Estuaries represent the primary linkage between the terrestrial and marine carbon cycles, and estuarine processing of riverine and coastal carbon plays a disproportionately large role in the global carbon cycle relative to the small areal extent of the estuarine environments. However, knowledge of the rate of organic carbon deposition and burial in estuarine sediments is lacking at regional scales. Data on surficial total organic carbon, linear sedimentation, and bulk density of estuarine sediments were compiled and categorized via a cluster analysis in order to estimate carbon deposition within the contiguous United States (CONUS). The cluster analysis broadly grouped estuaries by geography, but exceptions to geographic clustering highlighted differences within regions. A transfer function from deposition to burial based on linear sedimentation rate was used to estimate burial efficiency, and thus the rate of carbon burial within each cluster. We estimate organic carbon deposition rates within CONUS estuarine sediments to be 161 [121–217, 95% confidence] g C/m2/yr with a burial efficiency estimated at 38 [34–42, 95% confidence] %, which yields a long‐term burial rate of 64 [44–97, 95% confidence] g C/m2/yr. Spatially integrated organic deposition and burial rates are 11.3 [8.5–15.2, 95% confidence] and 4.5 [3.1–6.8, 95% confidence] Tg C/yr, respectively. Our findings allow a more thorough understanding of coastal carbon cycling, which is critical for both management purposes as well as for the assessment of the role of estuaries in past and future climate change.
Effects of Chemical Feedbacks on Decadal Methane Emissions Estimates
Authors: Nguyen Newton H. , Turner Alexander J. , Yin Yi , Prather Michael J. , Frankenberg Christian
Published: January 2020

The coupled chemistry of methane, carbon monoxide (CO), and hydroxyl radical (OH) can modulate methane's 9‐year lifetime. This is often ignored in methane flux inversions, and the impacts of neglecting interactive chemistry have not been quantified. Using a coupled‐chemistry box model, we show that neglecting the effect of methane source perturbation on [OH] can lead to a 25% bias in estimating abrupt changes in methane sources after only 10 years. Further, large CO emissions, such as from biomass burning, can increase methane concentrations by extending the methane lifetime through impacts on [OH]. Finally, we quantify the biases of including (or excluding) coupled chemistry in the context of recent methane and CO trends. Decreasing CO concentrations, beginning in the 2000's, have notable impacts on methane flux inversions. Given these nonnegligible errors, decadal methane emissions inversions should incorporate chemical feedbacks for more robust methane trend analyses and source attributions.
Episodic Lithospheric Deformation in Eastern Tibet Inferred From Seismic Anisotropy
Authors: Bao Xuewei , Song Xiaodong , Eaton David W. , Xu Yixian , Chen Hanlin
Published: January 2020

Mechanisms for uplift and deformation of the Tibetan Plateau remain vigorously debated; hypotheses include stepwise growth, distributed thickening, and crustal channel flow, each with a distinct anisotropic signature. We have developed a new azimuthally anisotropic shear velocity model for the lithosphere beneath eastern Tibet, based on ambient noise tomography from 643 seismic stations. In our model, the Tibetan upper crust is characterized by strong anisotropy with fast axes that correlate with surface geology and mantle anisotropy, suggesting the occurrence of coherent deformation. However, a much different picture emerges in the middle and lower crust, where anisotropy is disordered and weaker beneath the plateau than along its margins, inconsistent with the prediction of large‐scale eastward crust flow in eastern Tibet. Our observations are best explained by heterogeneous crustal thickening beneath the plateau with complex flow in the middle and lower crust, accompanied by asthenospheric upwelling along the southeastern plateau margin.
In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
Authors: Zhang Jun A. , Dunion Jason P. , Nolan David S.
Published: January 2020

Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundary layer, has not yet been investigated with observations. This study analyzes data from 2242 GPS dropsondes collected in mature hurricanes to investigate the diurnal variation of the mean boundary layer structure. A composite analysis is conducted to compare the kinematic and thermodynamic structure during nighttime (0–6 local time) vs in the afternoon (12–18 local time). The composites show that much stronger inflow occurs during nighttime and the moist entropy is also larger than that in the daytime. Grouping the dropsonde data into 6‐h time windows relative to the local time shows a clear diurnal signal of boundary layer inflow. The amplitude of the diurnal signal is largest at a radius of 250–500 km.
Structures of Multiple Large‐Scale Traveling Ionospheric Disturbances Observed by Dense Global Navigation Satellite System Networks in China
Authors: Chen Ge , Ding Feng , Wan Weixing , Hu Lianhuan , Zhao Xiukuan , Li Jianyong
Published: January 2020

The propagation features of three groups of multiple large‐scale traveling ionospheric disturbances (LSTIDs), which formed on 22 June 2015 during the passage of LSTIDs that propagated in different directions simultaneously over China, were investigated using the total electron content data from 341 Global Navigation Satellite System stations. The ranges of the periods and horizontal phase velocities of the LSTIDs were ~40–120 min and ~209–750 m/s, respectively. The first two groups were observed during 0700–1400 UT. The meeting of LSTIDs propagating in opposite directions yielded a differential of total electron content (DTEC) variation net structure, where the enhancement and reduction of DTEC amplitude appeared successively and reached a maximum amplitude of ~16% in the overlapping areas. DTEC series based on the observations of geostationary satellites from China's BeiDou Navigation Satellite System addressed the propagation and meeting of fronts. The third group contained two southward propagating LSTIDs, a northward LSTID, and a northwestward one. The joint propagation of the northward LSTID and northwestward LSTID led to a large‐amplitude mixed front, which was broadened both in latitudinal and meridional range. The mixed front moved northward at a distance of ~1,500‐km until it separated into two fronts, due to the difference in propagation velocities and directions. After separation, the northward LSTID continued to propagate and encountered a southward LSTID. The northwestward LSTID dissipated within 30 min in the northwest of China. Such multi‐LSTIDs have mainly been observed previously in equatorial regions, and our observations imply that the propagation of LSTIDs in the mid and low latitudes is more complicated than previously reported.
Response of Stratification Processes to Tidal Current Alteration due to Channel Narrowing and Deepening
Authors: Zhu Lei , He Qing , Shen Jian
Published: January 2020

Stratification in estuaries has received much focus due to its importance in estuarine hydrodynamics and material transport. By utilizing a well‐calibrated numerical model, in this work we investigate the changes in stratification in the deepened and narrowed North Passage of the Changjiang Estuary. Before channel narrowing and deepening, lateral straining, generated by the interaction between vertical shear in lateral flow and transverse salinity gradient, is the dominant factor that controls stratification. A two‐layer structure of the lateral flow strains the isopycnal transversely, resulting in rapid stratification from late flood to early ebb tide. Thus, maximum stratification occurs during the early ebb. Then, the stratification was suppressed by the vertical mixing and the less stratified water advected from upstream, even the vertical shear in along‐channel flow continued to strain the isopycnal. After channel deepening and narrowing, the salinity in the upper water column experienced a sharp vertical gradient during the entire tidal cycle, while the transverse salinity gradient and lateral flow are profoundly reduced. The impact of lateral straining on stratification becomes minor. The enhanced stratification results in a sharp decrease in turbulent mixing within the pycnocline. The water movement in the upper layer is in a free‐stream status and the tidal current speed increases significantly. The alteration of the vertical current structure enhances the along‐channel tidal straining and stratification is most vigorous on late ebb tide.
The First Andean Compressive Tectonic Phase: Sedimentologic and Structural Analysis of Mid‐Cretaceous Deposits in the Coastal Cordillera, Central Chile (32°50′S)
Authors: Boyce Daniel , Charrier Reynaldo , Farías Marcelo
Published: January 2020

We document the effects of major mid‐Cretaceous to Late Cretaceous compression within the volcanic arc of the western Gondwanan margin. The thinned Early Cretaceous Andean margin underwent rapid thickening and shortening‐related exhumation of magmatic arc rocks during compressional inversion of late Early Cretaceous intra‐arc basins. Clastic sedimentary and volcanic rocks recording this phase of initial Andean shortening correspond to the Las Chilcas Formation and are interpreted to have been deposited in a proximal retro‐arc position. A detailed analysis of these deposits reveals multiple periods during sustained compressional deformation throughout the latest Early and Late Cretaceous, from 105 to 83 Ma. This deformation is evidenced by the exhumation of older units in the Coastal Cordillera, together with the development of contractional structures and a strong sedimentary response involving deposition of approximately 3 km of synorogenic nonmarine clastic deposits of the Las Chilcas Formation. The structures and associated deposits suggest that the strongest uplift and deformation period occurred from 100 to 95 Ma, whereas subsequent Late Cretaceous deformation was less pronounced, possibly a result of eastward migration of deformation. This tectonic phase coincided with similar coeval synorogenic deposits in Chile and other Andean regions, which have been attributed to initial Andean shortening resulting from a major plate reorganization.
The Moving‐Boundary Approach for Modeling 2‐D Gravity‐Driven Stable and Unstable Flow in Partially Wettable Soils
Authors: Brindt Naaran , Wallach Rony
Published: January 2020

The moving‐boundary approach, which has been successfully used to model stable and unstable 1‐D flow in initially dry soils of various contact angles (Brindt & Wallach, 2017 https://doi.org/10.1002/2016WR019252), was extended here for 2‐D flow. The wetting front is the plume perimeter that is partly formed by the capillary driving force, the remaining part by the combined capillary and gravity driving forces. The moving‐boundary approach overcomes the limitation of the Richards equation for describing gravity‐driven unstable flow with nonmonotonic water‐content distribution. According to this approach, the 2‐D flow domain is divided into two subdomains with a sharp change in fluid saturation between them—the wetting front (moving boundary). The 2‐D Richards equation was solved for the subdomain behind the wetting front for a given flux boundary condition at the soil surface, while the location of the other boundary, for which a no‐flux condition is imposed, was part of the solution. The moving‐boundary solution was used after verification to demonstrate the synergistic effect of contact angle and incoming flux on flow stability and its associated plume shapes. The contact angle that hinders spontaneous invasion of the dry pores decreases the water‐entry capillary pressure, ψwe, while the flux‐dependent dynamic water‐entry value, ψwed, is even lower, both inducing water accumulation behind the wetting front (saturation overshoot). This innovative physically based model for the 2‐D unsaturated flow problem for an initially dry soil of zero and nonzero contact angle using the moving‐boundary approach fulfills several criteria raised by researchers to adequately describe gravity‐driven unstable flow.
An ultra-stable cytoplasmic antibody engineered for in vivo applications
Authors: Kabayama Hiroyuki , Takeuchi Makoto , Tokushige Naoko , Muramatsu Shin-ichi , Kabayama Miyuki , Fukuda Mitsunori , Yamada Yoshiyuki , Mikoshiba Katsuhiko
Published: January 2020

Targeting cytoplasmic protein–protein interactions with antibodies remains technically challenging, since antibodies expressed in the cytosol frequently form insoluble aggregates. Existing engineering methods are based on the notion that the estimated net charge at pH 7.4 affects stability; as such, they are unable to overcome this problem. Herein, we report a versatile method for engineering an ultra-stable cytoplasmic antibody (STAND), with a strong estimated net negative charge at pH 6.6, by fusing peptide tags with a highly negative charge and a low isoelectric point. Without the need for complicated amino acid substitutions, we convert aggregation-prone antibodies to STANDs that are useful for inhibiting in vivo transmitter release, modulating animal behaviour, and inhibiting in vivo cancer proliferation driven by mutated Kras—long recognised as an “undruggable” oncogenic protein. The STAND method shows promise for targeting endogenous cytoplasmic proteins in basic biology and for developing future disease treatments.
Ultrafast transient liquid assisted growth of high current density superconducting films
Authors: Soler L. , Jareño J. , Banchewski J. , Rasi S. , Chamorro N. , Guzman R. , Yáñez R. , Mocuta C. , Ricart S. , Farjas J. , Roura-Grabulosa P. , Obradors X. , Puig T.
Published: January 2020

The achievement of high growth rates in YBa2Cu3O7 epitaxial high-temperature superconducting films has become strategic to enable high-throughput manufacturing of long length coated conductors for energy and large magnet applications. We report on a transient liquid assisted growth process capable of achieving ultrafast growth rates (100 nm s−1) and high critical current densities (5 MA cm−2 at 77 K). This is based on the kinetic preference of Ba-Cu-O to form transient liquids prior to crystalline thermodynamic equilibrium phases, and as such is a non-equilibrium approach. The transient liquid-assisted growth process is combined with chemical solution deposition, proposing a scalable method for superconducting tapes manufacturing. Additionally, using colloidal solutions, the growth process is extended towards fabrication of nanocomposite films for enhanced superconducting properties at high magnetic fields. Fast acquisition in situ synchrotron X-ray diffraction and high resolution scanning transmission electron microscopy (STEM) become crucial measurements in disentangling key aspects of the growth process.
Mikania micrantha genome provides insights into the molecular mechanism of rapid growth
Authors: Liu Bo , Yan Jian , Li Weihua , Yin Lijuan , Li Ping , Yu Hanxia , Xing Longsheng , Cai Minling , Wang Hengchao , Zhao Mengxin , Zheng Jin , Sun Feng , Wang Zhenzhen , Jiang Zhaoyang , Ou Qiaojing , Li Shubin , Qu Lu , Zhang Qilei , Zheng Yaping , Qiao Xi , Xi Yu , Zhang Yan , Jiang Fan , Huang Cong , Liu Conghui , Ren Yuwei , Wang Sen , Liu Hangwei , Guo Jianyang , Wang Haihong , Dong Hui , Peng Changlian , Qian Wanqiang , Fan Wei , Wan Fanghao
Published: January 2020

Mikania micranthais one of the top 100 worst invasive species that can cause serious damage to natural ecosystems and substantial economic losses. Here, we present its 1.79 Gb chromosome-scale reference genome. Half of the genome is composed of long terminal repeat retrotransposons, 80% of which have been derived from a significant expansion in the past one million years. We identify a whole genome duplication event and recent segmental duplications, which may be responsible for its rapid environmental adaptation. Additionally, we show thatM. micranthaachieves higher photosynthetic capacity by CO2absorption at night to supplement the carbon fixation during the day, as well as enhanced stem photosynthesis efficiency. Furthermore, the metabolites ofM. micranthacan increase the availability of nitrogen by enriching the microbes that participate in nitrogen cycling pathways. These findings collectively provide insights into the rapid growth and invasive adaptation.
A transcomplementing gene drive provides a flexible platform for laboratory investigation and potential field deployment
Authors: López Del Amo Víctor , Bishop Alena L. , Sánchez C. Héctor M. , Bennett Jared B. , Feng Xuechun , Marshall John M. , Bier Ethan , Gantz Valentino M.
Published: January 2020

CRISPR-based gene drives can spread through wild populations by biasing their own transmission above the 50% value predicted by Mendelian inheritance. These technologies offer population-engineering solutions for combating vector-borne diseases, managing crop pests, and supporting ecosystem conservation efforts. Current technologies raise safety concerns for unintended gene propagation. Herein, we address such concerns by splitting the drive components, Cas9 and gRNAs, into separate alleles to form a trans-complementing split–gene-drive (tGD) and demonstrate its ability to promote super-Mendelian inheritance of the separate transgenes. This dual-component configuration allows for combinatorial transgene optimization and increases safety by restricting escape concerns to experimentation windows. We employ the tGD and a small–molecule-controlled version to investigate the biology of component inheritance and resistant allele formation, and to study the effects of maternal inheritance and impaired homology on efficiency. Lastly, mathematical modeling of tGD spread within populations reveals potential advantages for improving current gene-drive technologies for field population modification.
Rad50 zinc hook functions as a constitutive dimerization module interchangeable with SMC hinge
Authors: Tatebe Hisashi , Lim Chew Theng , Konno Hiroki , Shiozaki Kazuhiro , Shinohara Akira , Uchihashi Takayuki , Furukohri Asako
Published: January 2020

The human Mre11/Rad50 complex is one of the key factors in genome maintenance pathways. Previous nanoscale imaging by atomic force microscopy (AFM) showed that the ring-like structure of the human Mre11/Rad50 complex transiently opens at the zinc hook of Rad50. However, imaging of the human Mre11/Rad50 complex by high-speed AFM shows that the Rad50 coiled-coil arms are consistently bridged by the dimerized hooks while the Mre11/Rad50 ring opens by disconnecting the head domains; resembling other SMC proteins such as cohesin or condensin. These architectural features are conserved in the yeast and bacterial Mre11/Rad50 complexes. Yeast strains harboring the chimeric Mre11/Rad50 complex containing the SMC hinge of bacterial condensin MukB instead of the RAD50 hook properly functions in DNA repair. We propose that the basic role of the Rad50 hook is similar to that of the SMC hinge, which serves as rather stable dimerization interface.
Ultrafast shock synthesis of nanocarbon from a liquid precursor
Authors: Armstrong Michael R. , Lindsey Rebecca K. , Goldman Nir , Nielsen Michael H. , Stavrou Elissaios , Fried Laurence E. , Zaug Joseph M. , Bastea Sorin
Published: January 2020

Carbon nanoallotropes are important nanomaterials with unusual properties and promising applications. High pressure synthesis has the potential to open new avenues for controlling and designing their physical and chemical characteristics for a broad range of uses but it remains little understood due to persistent conceptual and experimental challenges, in addition to fundamental physics and chemistry questions that are still unresolved after many decades. Here we demonstrate sub-nanosecond nanocarbon synthesis through the application of laser-induced shock-waves to a prototypical organic carbon-rich liquid precursor—liquid carbon monoxide. Overlapping large-scale molecular dynamics simulations capture the atomistic details of the nanoparticles’ formation and evolution in a reactive environment and identify classical evaporation-condensation as the mechanism governing their growth on these time scales.
A robust and efficient method for Mendelian randomization with hundreds of genetic variants
Authors: Burgess Stephen , Foley Christopher N , Allara Elias , Staley James R , Howson Joanna M. M.
Published: January 2020

Mendelian randomization (MR) is an epidemiological technique that uses genetic variants to distinguish correlation from causation in observational data. The reliability of a MR investigation depends on the validity of the genetic variants as instrumental variables (IVs). We develop the contamination mixture method, a method for MR with two modalities. First, it identifies groups of genetic variants with similar causal estimates, which may represent distinct mechanisms by which the risk factor influences the outcome. Second, it performs MR robustly and efficiently in the presence of invalid IVs. Compared to other robust methods, it has the lowest mean squared error across a range of realistic scenarios. The method identifies 11 variants associated with increased high-density lipoprotein-cholesterol, decreased triglyceride levels, and decreased coronary heart disease risk that have the same directions of associations with various blood cell traits, suggesting a shared mechanism linking lipids and coronary heart disease risk mediated via platelet aggregation.
TDP-43 facilitates milk lipid secretion by post-transcriptional regulation of Btn1a1 and Xdh
Authors: Zhao Limin , Ke Hao , Xu Haibo , Wang Guo-Dong , Zhang Honglei , Zou Li , Xiang Shu , Li Mengyuan , Peng Li , Zhou Mingfang , Li Lingling , Ao Lei , Yang Qin , Shen Che-Kun James , Yi Ping , Wang Lu , Jiao Baowei
Published: January 2020

Milk lipid secretion is a critical process for the delivery of nutrition and energy from parent to offspring. However, the underlying molecular mechanism is less clear. Here we report that TDP-43, a RNA-binding protein, underwent positive selection in the mammalian lineage. Furthermore, TDP-43 gene (Tardbp) loss induces accumulation of large lipid droplets and severe lipid secretion deficiency in mammary epithelial cells to outside alveolar lumens, eventually resulting in lactation failure and pup starvation within three weeks postpartum. In human milk samples from lactating women, the expression levels of TDP-43 is positively correlated with higher milk output. Mechanistically, TDP-43 exerts post-transcriptional regulation ofBtn1a1andXdhmRNA stability, which are required for the secretion of lipid droplets from epithelial cells to the lumen. Taken together, our results highlights the critical role of TDP-43 in milk lipid secretion, providing a potential strategy for the screening and intervention of clinical lactation insufficiency.
Hepatic TET3 contributes to type-2 diabetes by inducing the HNF4α fetal isoform
Authors: Da Li  , Cao Tiefeng , Sun Xiaoli , Jin Sungho , Di Xie  , Huang Xinmei , Yang Xiaoyong , Carmichael Gordon G. , Taylor Hugh S. , Diano Sabrina , Huang Yingqun
Published: January 2020

Precise control of hepatic glucose production (HGP) is pivotal to maintain systemic glucose homeostasis. HNF4α functions to stimulate transcription of key gluconeogenic genes. HNF4α harbors two promoters (P2 and P1) thought to be primarily active in fetal and adult livers, respectively. Here we report that the fetal version of HNF4α is required for HGP in the adult liver. This isoform is acutely induced upon fasting and chronically increased in type-2 diabetes (T2D). P2 isoform induction occurs in response to glucagon-stimulated upregulation of TET3, not previously shown to be involved in HGP. TET3 is recruited to the P2 promoter by FOXA2, leading to promoter demethylation and increased transcription. While TET3 overexpression augments HGP, knockdown of either TET3 or the P2 isoform alone in the liver improves glucose homeostasis in dietary and genetic mouse models of T2D. These studies unmask an unanticipated, conserved regulatory mechanism in HGP and offer potential therapeutic targets for T2D.
Cerebrospinal fluid tracer efflux to parasagittal dura in humans
Authors: Ringstad Geir , Eide Per Kristian
Published: January 2020

The mechanisms behind molecular transport from cerebrospinal fluid to dural lymphatic vessels remain unknown. This study utilized magnetic resonance imaging along with cerebrospinal fluid tracer to visualize clearance pathways to human dural lymphatics in vivo. In 18 subjects with suspicion of various types of cerebrospinal fluid disorders, 3D T2-Fluid Attenuated Inversion Recovery, T1-black-blood, and T1 gradient echo acquisitions were obtained prior to intrathecal administration of the contrast agent gadobutrol (0.5 ml, 1 mmol/ml), serving as a cerebrospinal fluid tracer. Propagation of tracer was followed with T1 sequences at 3, 6, 24 and 48 h after the injection. The tracer escaped from cerebrospinal fluid into parasagittal dura along the superior sagittal sinus at areas nearby entry of cortical cerebral veins. The findings demonstrate that trans-arachnoid molecular passage does occur and suggest that parasagittal dura may serve as a bridging link between human brain and dural lymphatic vessels.
A transcriptome-wide antitermination mechanism sustaining identity of embryonic stem cells
Authors: Kainov Yaroslav A. , Makeyev Eugene V.
Published: January 2020

Eukaryotic gene expression relies on extensive crosstalk between transcription and RNA processing. Changes in this composite regulation network may provide an important means for shaping cell type-specific transcriptomes. Here we show that the RNA-associated protein Srrt/Ars2 sustains embryonic stem cell (ESC) identity by preventing premature termination of numerous transcripts at cryptic cleavage/polyadenylation sites in first introns. Srrt interacts with the nuclear cap-binding complex and facilitates recruitment of the spliceosome component U1 snRNP to cognate intronic positions. At least in some cases, U1 recruited in this manner inhibits downstream cleavage/polyadenylation events through a splicing-independent mechanism called telescripting. We further provide evidence that the naturally high expression of Srrt in ESCs offsets deleterious effects of retrotransposable sequences accumulating in its targets. Our work identifies Srrt as a molecular guardian of the pluripotent cell state.
Large-area, periodic, and tunable intrinsic pseudo-magnetic fields in low-angle twisted bilayer graphene
Authors: Shi Haohao , Zhan Zhen , Qi Zhikai , Huang Kaixiang , Veen Edo van , Silva-Guillén Jose Ángel , Zhang Runxiao , Li Pengju , Xie Kun , Ji Hengxing , Katsnelson Mikhail I. , Yuan Shengjun , Qin Shengyong , Zhang Zhenyu
Published: January 2020

A properly strained graphene monolayer or bilayer is expected to harbour periodic pseudo-magnetic fields with high symmetry, yet to date, a convincing demonstration of such pseudo-magnetic fields has been lacking, especially for bilayer graphene. Here, we report a definitive experimental proof for the existence of large-area, periodic pseudo-magnetic fields, as manifested by vortex lattices in commensurability with the moiré patterns of low-angle twisted bilayer graphene. The pseudo-magnetic fields are strong enough to confine the massive Dirac electrons into circularly localized pseudo-Landau levels, as observed by scanning tunneling microscopy/spectroscopy, and also corroborated by tight-binding calculations. We further demonstrate that the geometry, amplitude, and periodicity of the pseudo-magnetic fields can be fine-tuned by both the rotation angle and heterostrain. Collectively, the present study substantially enriches twisted bilayer graphene as a powerful enabling platform for exploration of new and exotic physical phenomena, including quantum valley Hall effects and quantum anomalous Hall effects.
A simple and versatile nickel platform for the generation of branched high molecular weight polyolefins
Authors: Liang Tao , Goudari Shabnam B. , Chen Changle
Published: January 2020

The development of high-performance transition metal catalysts has long been a major driving force in academic and industrial polyolefin research. Late transition metal-based olefin polymerization catalysts possess many unique properties, such as the ability to generate variously branched polyolefins using only ethylene as the feedstock and the capability of incorporating polar functionalized comonomers without protecting agents. Here we report the synthesis and (co)polymerization studies of a simple but extremely versatile α-imino-ketone nickel system. This type of catalyst is easy to synthesize and modify, and it is thermally stable and highly active during ethylene polymerization without the addition of any cocatalysts. Despite the sterically open nature, these catalysts can generate branched Ultra-High-Molecular-Weight polyethylene and copolymerize ethylene with a series of polar comonomers. The versatility of this platform has been further demonstrated through the synthesis of a dinuclear nickel catalyst and the installation of an anchor for catalyst heterogenization.
Competitive oxidation and ubiquitylation on the evolutionarily conserved cysteine confer tissue-specific stabilization of Insig-2
Authors: Zhou Zhang-Sen , Li Mei-Xin , Liu Jie , Jiao Hengwu , Xia Jing-Ming , Shi Xiong-Jie , Zhao Huabin , Chu Liping , Liu Jingrong , Qi Wei , Luo Jie , Song Bao-Liang
Published: January 2020

Insig-2 is an ER membrane protein negatively controlling lipid biosynthesis. Here, we find that Insig-2 is increased in the tissues, including liver, but unaltered in the muscle of gp78-deficient mice. In hepatocytes and undifferentiated C2C12 myoblasts, Insig-2 is ubiquitylated on Cys215 by gp78 and degraded. However, the C215 residue is oxidized by elevated reactive oxygen species (ROS) during C2C12 myoblasts differentiating into myotubes, preventing Insig-2 from ubiquitylation and degradation. The stabilized Insig-2 downregulates lipogenesis through inhibiting the SREBP pathway, helping to channel the carbon flux to ATP generation and protecting myotubes from lipid over-accumulation. Evolutionary analysis shows that the YECK (in which C represents Cys215 in human Insig-2) tetrapeptide sequence in Insig-2 is highly conserved in amniotes but not in aquatic amphibians and fishes, suggesting it may have been shaped by differential selection. Together, this study suggests that competitive oxidation-ubiquitylation on Cys215 of Insig-2 senses ROS and prevents muscle cells from lipid accumulation.
Bacterial Hsp70 resolves misfolded states and accelerates productive folding of a multi-domain protein
Authors: Imamoglu Rahmi , Balchin David , Hayer-Hartl Manajit , Hartl F. Ulrich
Published: January 2020

The ATP-dependent Hsp70 chaperones (DnaK in E. coli) mediate protein folding in cooperation with J proteins and nucleotide exchange factors (E. coli DnaJ and GrpE, respectively). The Hsp70 system prevents protein aggregation and increases folding yields. Whether it also enhances the rate of folding remains unclear. Here we show that DnaK/DnaJ/GrpE accelerate the folding of the multi-domain protein firefly luciferase (FLuc) ~20-fold over the rate of spontaneous folding measured in the absence of aggregation. Analysis by single-pair FRET and hydrogen/deuterium exchange identified inter-domain misfolding as the cause of slow folding. DnaK binding expands the misfolded region and thereby resolves the kinetically-trapped intermediates, with folding occurring upon GrpE-mediated release. In each round of release DnaK commits a fraction of FLuc to fast folding, circumventing misfolding. We suggest that by resolving misfolding and accelerating productive folding, the bacterial Hsp70 system can maintain proteins in their native states under otherwise denaturing stress conditions.
Superior polarization retention through engineered domain wall pinning
Authors: Zhang Dawei , Sando Daniel , Sharma Pankaj , Cheng Xuan , Ji Fan , Govinden Vivasha , Weyland Matthew , Nagarajan Valanoor , Seidel Jan
Published: January 2020

Ferroelectric materials possess a spontaneous polarization that is switchable by an electric field. Robust retention of switched polarization is critical for non-volatile nanoelectronic devices based on ferroelectrics, however, these materials often suffer from polarization relaxation, typically within days to a few weeks. Here we exploit designer-defect-engineered epitaxial BiFeO3 films to demonstrate polarization retention with virtually no degradation in switched nanoscale domains for periods longer than 1 year. This represents a more than 2000% improvement over the best values hitherto reported. Scanning probe microscopy-based dynamic switching measurements reveal a significantly increased activation field for domain wall movement. Atomic resolution scanning transmission electron microscopy indicates that nanoscale defect pockets pervade the entire film thickness. These defects act as highly efficient domain wall pinning centres, resulting in anomalous retention. Our findings demonstrate that defects can be exploited in a positive manner to solve reliability issues in ferroelectric films used in functional devices.
Polypeptide templating for designer hierarchical materials
Authors: Sun Hui , Marelli Benedetto
Published: January 2020

Despite advances in directing the assembly of biomacromolecules into well-defined nanostructures, leveraging pathway complexity of molecular disorder to order transition while bridging materials fabrication from nano- to macroscale remains a challenge. Here, we present templated crystallization of structural proteins to nanofabricate hierarchically structured materials up to centimeter scale, using silk fibroin as an example. The process involves the use of ordered peptide supramolecular assemblies as templates to direct the folding and assembly of silk fibroin into nanofibrillar structures. Silk polymorphs can be engineered by varying the peptide seeds used. Modulation of the relative concentration between silk fibroin and peptide seeds, silk fibroin molecular weight and pH allows control over nanofibrils morphologies and mechanical properties. Finally, facile integration of the bottom-up templated crystallization with emerging top-down techniques enables the generation of macroscopic nanostructured materials with potential applications in information storage/encryption, surface functionalization, and printable three-dimensional constructs of customized architecture and controlled anisotropy.