bluuebunny/crossref_metadata_2025 huggingface dataset:
The Digital Storywork Partnership: Community-Centered Social Studies to Revitalize Indigenous Histories and Cultural Knowledges
Authors: Stanton Christine Rogers , Hall Brad , Carjuzaa Jioanna
Published: September 2018

Indigenous communities have always cultivated social studies learning that is interactive, dynamic, and integrated with traditional knowledges. To confront the assimilative and deculturalizing education that accompanied European settlement of the Americas, Montana has adopted Indian Education for All (IEFA). This case study evaluates the Digital Storywork Partnership (DSP), which strives to advance the goals of IEFA within and beyond the social studies classroom through community-centered research and filmmaking. Results demonstrate the potential for DSP projects to advance culturally revitalizing education, community connectedness, and identity-development. The DSP offers a model for social studies education that is not only culturally affirming and revitalizing for Indigenous communities, but also holds potential for use in all communities. We conclude with recommendations for educators, scholars, and community members engaged in similar efforts.
Numerical investigation of the effect of disk position on the aerodynamic heating and drag of a spiked blunt body in hypersonic flow
Authors: Yadav R. , Bodavula A. , Joshi S.
Published: September 2018

Detailed numerical simulations have been carried out on a spiked blunt body with multiple hemispherical disks using a commercial CFD code in order to investigate their effectiveness in reducing the aerodynamic drag and heating. The base configuration is a hemispherical cylinder whose diameter is 40 mm with an overall length of 70 mm. The lengths of the aerospikes investigated are 1, 1.5, 2 and 2.5 times the base diameter of the cylinder and the radii of the aerodisks are varied between 0.05, 0.1, 0.15 and 0.2 times the diameter of the cylinder. Besides these, the position of the aerodisks is varied with the rearmost aerodisk placed at 25%, 50% and 75% along the length of the aerospike and the intermediate aerodisk for three-disk cases, positioned at 25%, 50% and 75% of the distance between the front and the rearmost disk. All the investigations have carried out at a freestream Mach number of 6.2 and Reynolds number of 2.64 × 107/m. It has been observed that the multidisk spikes are advantageous for the purpose of reduction of both aerodynamic drag and heating at hypersonic speed. The two aerodisk spiked configurations show better results in terms of aerodynamic heating and drag in comparison to the single-disk aerospikes while the three-disk spikes yield only a marginal reduction in aerodynamic drag over the two-disk configurations. For reduction of heat fluxes and heat transfer rates though, the three-disk configurations are extremely advantageous and give much larger reductions are compared to the two-disk configurations.
Experimental advanced RNP to xLS approaches with vertical path coding and automatic landings
Authors: Dautermann T. , Ludwig T. , Geister R. , Blase T.
Published: September 2018

We report on the flight test results of an Airbus 320 during novel advanced required navigation performance (RNP) procedures which contain a fixed radius turn that delivers the aircraft onto a short instrument landing system (ILS) precision final. Moreover, the advanced RNP part contains altitude constraints and/or a coded vertical path angle. The approaches were flown automatically with guidance and autothrust as computed by the flight management system. We investigated the use of the fixed radius in conjunction with vertical path options onto (a) the performance of the speed profile for arrival time optimisation, (b) the vertical path during the RNP part of the procedure and (c) the performance of the autoland capability after a curved transition onto an ILS.

For the trials, we designed five instrument approaches to a runway equipped with ILS. A RF curve terminates at the ILS intercept point at heights of 550, 750, 1000, 1500 and 2000 ft above aerodrome level and each approach had four different initial approach fixes which corresponded to a track angle change of 30°, 60°, 90° and 180° during the constant radius turn-to-final. We constructed the procedure such that the altitude constraints at initial, intermediate and final approach fix describe a continuous vertical path with minus 2° inclination, transitioning to the –3° glide path of the ILS and intercepting the glide path from below. In all cases, the land mode of the flight guidance computer became active between 316 and 381ft radar altitude. The vertical path following error depended on the coding of the procedure in the database. With coded vertical path angle and altitude constraints, the vertical path following error was never greater than +57 m (above desired flight path) during the RNP part when flown by the automatic flight guidance system without any pilot intervention.
Foliated hyperbolicity and foliations with hyperbolic leaves
Authors: BONATTI CHRISTIAN , GÓMEZ-MONT XAVIER , MARTÍNEZ MATILDE
Published: September 2018

Given a lamination in a compact space and a laminated vector field $X$ which is hyperbolic when restricted to the leaves of the lamination, we distinguish a class of $X$-invariant probabilities that describe the behavior of almost every $X$-orbit in every leaf, which we call Gibbs $u$-states. We apply this to the case of foliations in compact manifolds having leaves with negative curvature, using the foliated hyperbolic vector field on the unit tangent bundle to the foliation generating the leaf geodesics. When the Lyapunov exponents of such ergodic Gibbs $u$-states are negative, it is an SRB measure (having a positive Lebesgue basin of attraction). When the foliation is by hyperbolic leaves, this class of probabilities coincide with the classical harmonic measures introduced by Garnett. Furthermore, if the foliation is transversally conformal and does not admit a transverse invariant measure we show that there are finitely many ergodic Gibbs $u$-states, each supported in one minimal set of the foliation, each having negative Lyapunov exponents, and the union of their basins of attraction has full Lebesgue measure. The leaf geodesics emanating from a point have a proportion whose asymptotic statistics are described by each of these ergodic Gibbs $u$-states, giving rise to continuous visibility functions of the attractors. Reversing time, by considering $-X$, we obtain the existence of the same number of repellers of the foliated geodesic flow having the same harmonic measures as projections to $M$. In the case of only one attractor, we obtain a north to south pole dynamics.
Clostridium difficile colonization among patients with clinically significant diarrhea and no identifiable cause of diarrhea
Authors: Dubberke Erik R. , Reske Kimberly A. , Hink Tiffany , Kwon Jennie H. , Cass Candice , Bongu Jahnavi , Burnham Carey-Ann D. , Henderson Jeffrey P.
Published: September 2018

Objective

To determine the prevalence of Clostridium difficile colonization among patients who meet the 2017 IDSA/SHEA C. difficile infection (CDI) Clinical Guideline Update criteria for the preferred patient population for C. difficile testing.

Design

Retrospective cohort.

Setting

Tertiary-care hospital in St. Louis, Missouri.

Patients

Patients whose diarrheal stool samples were submitted to the hospital’s clinical microbiology laboratory for C. difficile testing (toxin EIA) from August 2014 to September 2016.

Interventions

Electronic and manual chart review were used to determine whether patients tested for C. difficile toxin had clinically significant diarrhea and/or any alternate cause for diarrhea. Toxigenic C. difficile culture was performed on all stool specimens from patients with clinically significant diarrhea and no known alternate cause for their diarrhea.

Results

A total of 8,931 patients with stool specimens submitted were evaluated: 570 stool specimens were EIA positive (+) and 8,361 stool specimens were EIA negative (−). Among the EIA+stool specimens, 107 (19% of total) were deemed eligible for culture. Among the EIA− stool specimens, 515 (6%) were eligible for culture. One EIA+stool specimen (1%) was toxigenic culture negative. Among the EIA− stool specimens that underwent culture, toxigenic C. difficile was isolated from 63 (12%).

Conclusions

Most patients tested for C. difficile do not have clinically significant diarrhea and/or potential alternate causes for diarrhea. The prevalence of toxigenic C. difficile colonization among EIA− patients who met the IDSA/SHEA CDI guideline criteria for preferred patient population for C. difficile testing was 12%.
ARCHAEOLOGY OF DESTRUCTION: TOPRAKKALE
Authors: Genç Bülent
Published: September 2018

Toprakkale is the site that constitutes the starting point for the archaeology of Urartu, but the history of the largely destructive early excavations of the site is shrouded in darkness. The presence of items on the antiquities market said to come from the Van region attracted the interest of Austen Henry Layard, which led to brief excavations at the site of Toprakkale by the British Museum under Hormuzd Rassam in 1877, followed by further also brief investigations by K. Kamsarakan as well as continued illegal excavations. It is commonly held that Carl Friedrich Lehmann-Haupt and Waldemar Belck excavated here between 1898–1899, but research performed in the Ottoman Archives of the Prime Minister's Office reveals their claim to have excavated there to be fraudulent and empty. This article uses primary source material from Ottoman archives to investigate the excavation history of one of the most iconic sites for the beginnings of Urartian Studies, and compels us to re-evaluate what we think we know about Toprakkale and the provenance of the objects associated with it.
Gender similarity, coworker support, and job attitudes: An occupation’s creative requirement can make a difference
Authors: Koseoglu Gamze , Blum Terry C , Shalley Christina E
Published: September 2018

By introducing gender similarity as a contextual antecedent of coworker support, we examined the mediating role of coworker support for the relationship between workgroup gender similarity and job attitudes. In addition, we explored how a creative requirement, which is an occupational characteristic, can influence the relationship between coworker support and job attitudes above and beyond the role of supervisor support and organizational support. Results based on 975 full-time employees across a wide variety of occupations and industries indicated that as expected coworker support can serve as an underlying mechanism in the relationship between the relational demography of a workplace and employees’ job satisfaction and intention to quit. Furthermore, coworker support was significantly related to job satisfaction only for those occupations that required high levels of creativity. Finally, the creative requirement of an occupation moderated the indirect effect of gender similarity on job satisfaction through coworker support.
COMPUTING LIMITING LOCAL POWERS AND POWER ENVELOPES OF PANEL MA UNIT ROOT TESTS AND STATIONARITY TESTS
Authors: Tanaka Katsuto
Published: September 2018

The present article discusses panel unit root tests for two classes of models. One is the moving average (MA) model and the other is the error components model. We conduct score type tests for these models, allowing for various types of regressors, and examine the cross-sectional effect explicitly by presenting an efficient way of computing limiting local powers. It is found that the existence of common regressors does not affect the asymptotic behavior of tests, although heterogeneous regressors do. We also derive the limiting power envelopes for some simple panel models, which shows that the score type panel tests are asymptotically efficient, unlike the time series case.
Oscillation and variation for the Riesz transform associated with Bessel operators
Authors: Wu Huoxiong , Yang Dongyong , Zhang Jing
Published: September 2018

Let λ > 0 and let

be the Bessel operator on ℝ+ := (0,∞). We show that the oscillation operator 𝒪(RΔλ,∗) and variation operator 𝒱ρ(RΔλ,∗) of the Riesz transform RΔλ associated with Δλ are both bounded on Lp(ℝ+, dmλ) for p ∈ (1,∞), from L1(ℝ+, dmλ) to L1,∞(ℝ+, dmλ), and from L∞(ℝ+, dmλ) to BMO(ℝ+, dmλ), where ρ ∈ (2,∞) and dmλ(x) := x2λ dx. As an application, we give the corresponding Lp-estimates for β-jump operators and the number of up-crossings.
Performance Evaluation of Kinematic BDS/GNSS Real-Time Precise Point Positioning for Maritime Positioning
Authors: Yang Fuxin , Zhao Lin , Li Liang , Feng Shaojun , Cheng Jianhua
Published: September 2018

Real-time Precise Point Positioning (PPP) has been evolved as a cost-effective technique for highly precise maritime positioning. For a long period, maritime PPP technology has mainly relied on the Global Positioning System (GPS). With the revitalisation of GLONASS and the emerging BeiDou navigation satellite system (BDS), it is now feasible to investigate real-time navigation performance of multi-constellation maritime PPP with GPS, BDS and GLONASS. In this contribution, we focus on maritime PPP performance using real world maritime kinematic data and real-time satellite correction products. The results show that BDS has lower position accuracy and slower convergence time than GPS. The BDS and GPS combination has the best performance among the dual-constellation configurations. Meanwhile, the integration of BDS, GLONASS and GPS significantly improves the position accuracy and the convergence time. Some outliers in the single constellation configuration can be mitigated when multi-constellation observations are utilised.
Migration and a New Landscape of Forest Use and Conservation
Authors: Robson James P. , Klooster Daniel J.
Published: September 2018

The nature of migration–forest linkages in migrant-sending regions is underreported and poorly understood. In rural Latin America and elsewhere, out-migration, together with agricultural crises and the deterritorialization of rural livelihood, are transforming forests and the communities that manage them. Drawing on research in indigenous communities of Oaxaca (Mexico), we identify the parameters of a new landscape of forest use and conservation, finding that: migration challenges community practices for self-governance of forest resources; declines in agriculture create new spaces for forest recovery and use; and forest conservation policies create economic opportunities around both extractive and non-extractive forest use.
The Perceived Benefits of Protected Areas in the Virunga-bwindi Massif
Authors: Tolbert Sarah , Makambo Wellard , Asuma Stephen , Musema Altor , Mugabukomeye Benjamin
Published: September 2018

Despite decades of continuous research highlighting the biological success of mountain gorilla conservation in the Virunga-Bwindi Massif, there is little knowledge of whether people living near the mountain gorilla parks perceive benefits from protected areas (PAs). This paper is the first study in the region to use the sustainable livelihoods framework to understand drivers of local perceptions of PA benefits. We used a logit regression to examine the relationship between household socioeconomic characteristics and the costs and benefits that 752 men and women living near mountain gorilla PAs reported. Integrated conservation and development projects (ICDPs) in the Virunga-Bwindi Massif have improved perceptions of mountain gorilla PAs, but they need to prioritize projects that improve human and social capital. The frustration voiced about inequitable benefit distribution highlights the need for further social equity research to ensure ICDPs, including revenue-sharing schemes, are managed transparently and equitably.
The Failed Diffusion of the Unicameral State Legislature, 1934–1944
Authors: Myers Adam S.
Published: September 2018

The early twentieth-century witnessed numerous efforts to reform state government institutions, resulting in the widespread adoption of such reforms as the direct primary and citizen initiative. By contrast, efforts to establish unicameral state legislatures experienced success in just one state: Nebraska. In this article, I examine why movements to adopt one-house legislatures in other states failed in the wake of the Nebraska breakthrough of 1934. Using a most-similar case study research design, I compare the successful Nebraska effort to unsuccessful subsequent efforts in Ohio and Missouri, and I point to rural opposition as being the decisive factor explaining divergent outcomes across the three states. In Nebraska, the lack of malapportionment in the bicameral legislature meant that rural communities did not fear that unicameralism would lead to their diminished influence in state government, but in Ohio and Missouri (where malapportionment was high) rural communities used their structural advantages in state politics to shut down unicameralism efforts. The article's findings suggest that the bicameral state legislature is an important institutional legacy of the bygone era of rural dominance in American politics.
Pericarp thickness of Korean maize landraces
Authors: So Yoon-Sup
Published: September 2018

Thin pericarp is one of crucial selection criteria for high-tender waxy corn hybrid development. A pericarp thickness of 2414 maize landrace accessions including 87 public waxy inbred lines was investigated to select accessions with thin pericarp and to broaden genetic diversity among waxy corn cultivars. Observed pericarp thickness of the 2414 accessions ranged from 16.0 ± 1.56 to 139.2 ± 39.55 µm with the average of 47.7 ± 13.15 µm. More than half of the accessions were below the suggested thickness of <50 µm for high-tender waxy corn hybrid development. Large sample size resulted in significant differences among endosperm types and among collection provinces. This, however, may not translate into considerable difference in tenderness since most averages of different types and collection provinces were <50 µm. Positive correlation (r= 0.55) between the average and standard deviation of pericarp thickness implied that more samples are needed to achieve same level of precision when it comes to selection for thick pericarp than that for thin pericarp. Top 10% thin-pericarped waxy landrace accessions were intercrossed to form a new waxy corn population from this result.
Lessons from Mexico’s Earthquake Early Warning System
Authors: Allen Richard , Cochran Elizabeth , Huggins Thomas , Miles Scott , Otegui Diego
Published: September 2018

The devastating 2017 Puebla quake provides an opportunity to assess how citizens perceive and use the Mexico City earthquake early warning system.
How Did Life Learn to Breathe?
Authors: Joel Lucas
Published: September 2018

Scientists unravel the conditions under which life evolved to breathe oxygen—and the findings have some stellar implications.
Cassini/MIMI Observations on the Dungey Cycle Reconnection and Kelvin‐Helmholtz Instability in Saturn's Magnetosphere
Authors: Dialynas Konstantinos
Published: September 2018

A new composite analysis of ∼13 years of Cassini's Charge Energy Mass Spectrometer measurements, presented by Allen et al. (2018, https://doi.org/10.1029/2018JA025262), suggests that the asymmetrically distributed suprathermal He++ in Saturn's magnetosphere is due to Dungey cycle related reconnection and Kelvin‐Helmholtz instabilities that provide paths to the solar wind plasma to reach distances even deep in the inner magnetosphere and accumulate in the ring current region, together with the internally sourced plasma. The results provide a significant addition to the ongoing discussions concerning the contribution of the solar wind input to the dynamics of an otherwise rotationally driven system, such as Saturn's magnetosphere.
Satellite Detection of Water Stress Effects on Terrestrial Latent Heat Flux With MODIS Shortwave Infrared Reflectance Data
Authors: Yao Yunjun , Liang Shunlin , Cao Bao , Liu Shaomin , Yu Guirui , Jia Kun , Zhang Xiaotong , Zhang Yuhu , Chen Jiquan , Fisher Joshua B.
Published: September 2018

The MODerate‐resolution Imaging Spectroradiometer (MODIS) provides spatially contiguous measurements of terrestrial biophysical variables, which can be used to estimate the terrestrial latent heat flux (LE). MODIS‐derived shortwave infrared reflectance (SWIR) metrics (SWIRs) are sensitive to the soil moisture and vegetation water stress. In this study, we used the MODIS‐derived SWIRs with eddy covariance flux measurements obtained from 25 flux tower sites representing 10 different land cover types within China to evaluate the sensitivity of SWIRs to ground‐measured evaporation fraction and LE. The water constraint metrics determined using the MODIS‐derived SWIR generally corresponded better with the ground‐measured evaporation fraction values than those obtained without using SWIR. The MODIS‐derived SWIRs were used as proxies for the soil and vegetation water supply constraints in a revised Priestley‐Taylor algorithm to estimate the terrestrial LE. The estimated LE using the MODIS‐derived SWIRs generally corresponded well with the ground‐measured LE (0.56 ≤ R2 ≤ 0.97) for most of the flux tower sites. Regional algorithm sensitivity analysis using the MODIS‐derived SWIRs as water supply proxies demonstrated that water limitations reduce LE by more than 53% over China, and the atmospheric vapor pressure deficit and relative humidity are not sufficient to characterize both the atmosphere demand and water supply for LE estimation. Our results demonstrate the potential of using MODIS‐derived SWIRs to characterize soil and vegetation water supply factors for determining LE, where the relatively high spatial and temporal resolutions (500 m and daily) are closer to the scale of the eddy covariance ground measurements.
Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments
Authors: Fisher Jenny A. , Atlas Elliot L. , Barletta Barbara , Meinardi Simone , Blake Donald R. , Thompson Chelsea R. , Ryerson Thomas B. , Peischl Jeff , Tzompa‐Sosa Zitely A. , Murray Lee T.
Published: September 2018

Alkyl nitrates (RONO2) are important components of tropospheric reactive nitrogen that serve as reservoirs for nitrogen oxides (NOx≡ NO + NO2). Here we implement a new simulation of atmospheric methyl, ethyl, and propyl nitrate chemistry in a global chemical transport model (GEOS‐Chem). We show that the model can reproduce the spatial and seasonal variability seen in a 20‐year ensemble of airborne observations. Methyl nitrate accounts for 17 Gg N globally, with maxima over the tropical Pacific and Southern Ocean. Propyl nitrate is enhanced in continental boundary layers, but its global impact (6 Gg N) is limited by a short lifetime (8 days vs. 26 days for methyl nitrate and 14 days for ethyl nitrate) that inhibits long‐range transport. Ethyl nitrate has the smallest impact of the three species (4 Gg N). We find that methyl nitrate is the dominant form of reactive nitrogen (NOy) in the Southern Ocean marine boundary layer, where its addition to the model corrects a large NOy underestimate in austral winter relative to recent aircraft data. RONO2 serve as a small net NOx source to the marine troposphere, except in the northern midlatitudes where the continental outflow is enriched in precursors that promote NOx loss via RONO2 formation. Recent growth in NOx emissions from East Asia has enhanced the role of RONO2 as a source of NOx to the remote free troposphere. This relationship implies projected future NOx emissions growth across the southern hemisphere may further enhance the importance of RONO2 as a NOx reservoir.
Sheet Flow Effects on Sediment Transport in a Degraded Ridge‐and‐Slough Wetland: Insights Using Molecular Markers
Authors: Regier Peter , He Ding , Saunders Colin J. , Jara Blanca , Hansen Chris , Newman Sue , Tate‐Boldt Erik , Coronado‐Molina Carlos , Jaffé Rudolf
Published: September 2018

Wetland ecosystems are often characterized by self‐organized landscape patterning, driven by abiotic and biotic factors. In the Florida Everglades, natural sheet flow is hypothesized to have distributed sediments to form the pattern of linear emergent ridges and submerged sloughs. Drainage and barriers to flow have degraded these microtopographic features. As part of the Comprehensive Everglades Restoration Plan, the Decompartmentalization Physical Model is a landscape‐scale experiment to evaluate ecosystem responses to restored sheet flow by increasing freshwater inputs and removing barriers to flow. To test the proposed mechanism that flow rebuilds ridge‐slough microtopography by remobilizing slough sediments into ridges, four molecular markers capable of distinguishing ridge, slough, and microbial sources were evaluated in flocculent benthic sediments (floc) and advected sediments (collected in traps) during preflow, high‐flow, and postflow conditions over 4 years. The combined use of the four biomarkers, namely, the aquatic proxy (Paq), C20 highly branched isoprenoids, kaurenes, and botryococcenes, showed compositional patterns that clearly distinguished ridge and slough organic matter. Of these molecular parameters, the Paq was the most reliable in distinguishing among organic matter sources. Long‐term patterns in floc Paq at ridge and slough sites indicate a general increase, indicative of preferential mobilization of slough material. The Paq values for advected sediments are also strongly associated with slough environments, supporting temporal trends in floc samples. Our results tentatively confirm the hypothesis that increased flow in degraded ridge‐and‐slough wetlands, and associated sediment transport, is a potentially viable mechanism to restore historic patterns of microtopography.
Cross-exchange of B-vitamins underpins a mutualistic interaction between Ostreococcus tauri and Dinoroseobacter shibae
Authors: Cooper Matthew B , Kazamia Elena , Helliwell Katherine E , Kudahl Ulrich Johan , Sayer Andrew , Wheeler Glen L , Smith Alison G
Published: September 2018

Ostreococcus tauri, a picoeukaryotic alga that contributes significantly to primary production in oligotrophic waters, has a highly streamlined genome, lacking the genetic capacity to grow without the vitamins thiamine (B1) and cobalamin (B12). Here we demonstrate that the B12 and B1 auxotrophy of O. tauri can be alleviated by co-culturing with a heterotrophic bacterial partner Dinoroseobacter shibae, a member of the Rhodobacteraceae family of alpha-proteobacteria, genera of which are frequently found associated with marine algae. D. shibae lacks the complete pathway to synthesise three other B-vitamins: niacin (B3), biotin (B7), and p-aminobenzoic acid (a precursor for folate, B9), and the alga is in turn able to satisfy the reciprocal vitamin requirements of its bacterial partner in a stable long-term co-culture. Bioinformatics searches of 197 representative marine bacteria with sequenced genomes identified just nine species that had a similar combination of traits (ability to make vitamin B12, but missing one or more genes for niacin and biotin biosynthesis enzymes), all of which were from the Rhodobacteraceae. Further analysis of 70 species from this family revealed the majority encoded the B12 pathway, but only half were able to make niacin, and fewer than 13% biotin. These characteristics may have either contributed to or resulted from the tendency of members of this lineage to adopt lifestyles in close association with algae. This study provides a nuanced view of bacterial–phytoplankton interactions, emphasising the complexity of the sources, sinks and dynamic cycling between marine microbes of these important organic micronutrients.
Mapping of histone-binding sites in histone replacement-completed spermatozoa
Authors: Yoshida Keisuke , Muratani Masafumi , Araki Hiromitsu , Miura Fumihito , Suzuki Takehiro , Dohmae Naoshi , Katou Yuki , Shirahige Katsuhiko , Ito Takashi , Ishii Shunsuke
Published: September 2018

The majority of histones are replaced by protamines during spermatogenesis, but small amounts are retained in mammalian spermatozoa. Since nucleosomes in spermatozoa influence epigenetic inheritance, it is important to know how histones are distributed in the sperm genome. Conflicting data, which may result from different conditions used for micrococcal nuclease (MNase) digestion, have been reported: retention of nucleosomes at either gene promoter regions or within distal gene-poor regions. Here, we find that the swim-up sperm used in many studies contain about 10% population of sperm which have not yet completed the histone-to-protamine replacement. We develop a method to purify histone replacement-completed sperm (HRCS) and to completely solubilize histones from cross-linked HRCS without MNase digestion. Our results indicate that histones are retained at specific promoter regions in HRCS. This method allows the study of epigenetic status in mature sperm.
Locally-curved geometry generates bending cracks in the African elephant skin
Authors: Martins António F. , Bennett Nigel C. , Clavel Sylvie , Groenewald Herman , Hensman Sean , Hoby Stefan , Joris Antoine , Manger Paul R. , Milinkovitch Michel C.
Published: September 2018

An intricate network of crevices adorns the skin surface of the African bush elephant, Loxodonta africana. These micrometre-wide channels enhance the effectiveness of thermal regulation (by water retention) as well as protection against parasites and intense solar radiation (by mud adherence). While the adaptive value of these structures is well established, their morphological characterisation and generative mechanism are unknown. Using microscopy, computed tomography and a custom physics-based lattice model, we show that African elephant skin channels are fractures of the animal brittle and desquamation-deficient skin outermost layer. We suggest that the progressive thickening of the hyperkeratinised stratum corneum causes its fracture due to local bending mechanical stress in the troughs of a lattice of skin millimetric elevations. The African elephant skin channels are therefore generated by thickening of a brittle material on a locally-curved substrate rather than by a canonical tensile cracking process caused by frustrated shrinkage.
Targeting PFKFB3 radiosensitizes cancer cells and suppresses homologous recombination
Authors: Gustafsson Nina M. S. , Färnegårdh Katarina , Bonagas Nadilly , Ninou Anna Huguet , Groth Petra , Wiita Elisee , Jönsson Mattias , Hallberg Kenth , Lehto Jemina , Pennisi Rosa , Martinsson Jessica , Norström Carina , Hollers Jessica , Schultz Johan , Andersson Martin , Markova Natalia , Marttila Petra , Kim Baek , Norin Martin , Olin Thomas , Helleday Thomas
Published: September 2018

The glycolytic PFKFB3 enzyme is widely overexpressed in cancer cells and an emerging anti-cancer target. Here, we identify PFKFB3 as a critical factor in homologous recombination (HR) repair of DNA double-strand breaks. PFKFB3 rapidly relocates into ionizing radiation (IR)-induced nuclear foci in an MRN-ATM-γH2AX-MDC1-dependent manner and co-localizes with DNA damage and HR repair proteins. PFKFB3 relocalization is critical for recruitment of HR proteins, HR activity, and cell survival upon IR. We develop KAN0438757, a small molecule inhibitor that potently targets PFKFB3. Pharmacological PFKFB3 inhibition impairs recruitment of ribonucleotide reductase M2 and deoxynucleotide incorporation upon DNA repair, and reduces dNTP levels. Importantly, KAN0438757 induces radiosensitization in transformed cells while leaving non-transformed cells unaffected. In summary, we identify a key role for PFKFB3 enzymatic activity in HR repair and present KAN0438757, a selective PFKFB3 inhibitor that could potentially be used as a strategy for the treatment of cancer.
Circuit quantum electrodynamics of granular aluminum resonators
Authors: Maleeva N. , Grünhaupt L. , Klein T. , Levy-Bertrand F. , Dupre O. , Calvo M. , Valenti F. , Winkel P. , Friedrich F. , Wernsdorfer W. , Ustinov A. V. , Rotzinger H. , Monfardini A. , Fistul M. V. , Pop I. M.
Published: September 2018

Granular aluminum (grAl) is a promising high kinetic inductance material for detectors, amplifiers, and qubits. Here we model the grAl structure, consisting of pure aluminum grains separated by thin aluminum oxide barriers, as a network of Josephson junctions, and we calculate the dispersion relation and nonlinearity (self-Kerr and cross-Kerr coefficients). To experimentally study the electrodynamics of grAl thin films, we measure microwave resonators with open-boundary conditions and test the theoretical predictions in two limits. For low frequencies, we use standard microwave reflection measurements in a low-loss environment. The measured low-frequency modes are in agreement with our dispersion relation model, and we observe self-Kerr coefficients within an order of magnitude from our calculation starting from the grAl microstructure. Using a high-frequency setup, we measure the plasma frequency of the film around 70 GHz, in agreement with the analytical prediction.
Solution-processed perovskite light emitting diodes with efficiency exceeding 15% through additive-controlled nanostructure tailoring
Authors: Ban Muyang , Zou Yatao , Rivett Jasmine P. H. , Yang Yingguo , Thomas Tudor H. , Tan Yeshu , Song Tao , Gao Xingyu , Credgington Dan , Deschler Felix , Sirringhaus Henning , Sun Baoquan
Published: September 2018

Organometal halide perovskites (OHP) are promising materials for low-cost, high-efficiency light-emitting diodes. In films with a distribution of two-dimensional OHP nanosheets and small three-dimensional nanocrystals, an energy funnel can be realized that concentrates the excitations in highly efficient radiative recombination centers. However, this energy funnel is likely to contain inefficient pathways as the size distribution of nanocrystals, the phase separation between the OHP and the organic phase. Here, we demonstrate that the OHP crystallite distribution and phase separation can be precisely controlled by adding a molecule that suppresses crystallization of the organic phase. We use these improved material properties to achieve OHP light-emitting diodes with an external quantum efficiency of 15.5%. Our results demonstrate that through the addition of judiciously selected molecular additives, sufficient carrier confinement with first-order recombination characteristics, and efficient suppression of non-radiative recombination can be achieved while retaining efficient charge transport characteristics.
Natural variation at XND1 impacts root hydraulics and trade-off for stress responses in Arabidopsis
Authors: Tang Ning , Shahzad Zaigham , Lonjon Fabien , Loudet Olivier , Vailleau Fabienne , Maurel Christophe
Published: September 2018

Soil water uptake by roots is a key component of plant performance and adaptation to adverse environments. Here, we use a genome-wide association analysis to identify the XYLEM NAC DOMAIN 1 (XND1) transcription factor as a negative regulator of Arabidopsis root hydraulic conductivity (Lpr). The distinct functionalities of a series of natural XND1 variants and a single nucleotide polymorphism that determines XND1 translation efficiency demonstrate the significance of XND1 natural variation at species-wide level. Phenotyping of xnd1 mutants and natural XND1 variants show that XND1 modulates Lpr through action on xylem formation and potential indirect effects on aquaporin function and that it diminishes drought stress tolerance. XND1 also mediates the inhibition of xylem formation by the bacterial elicitor flagellin and counteracts plant infection by the root pathogen Ralstonia solanacearum. Thus, genetic variation at XND1, and xylem differentiation contribute to resolving the major trade-off between abiotic and biotic stress resistance in Arabidopsis.
Electrical conductivity and magnetic dynamos in magma oceans of Super-Earths
Authors: Soubiran François , Militzer Burkhard
Published: September 2018

Super-Earths are extremely common among the numerous exoplanets that have been discovered. The high pressures and temperatures in their interiors are likely to lead to long-lived magma oceans. If their electrical conductivity is sufficiently high, the mantles of Super-Earth would generate their own magnetic fields. With ab initio simulations, we show that upon melting, the behavior of typical mantle silicates changes from semi-conducting to semi-metallic. The electrical conductivity increases and the optical properties are substantially modified. Melting could thus be detected with high-precision reflectivity measurements during the short time scales of shock experiments. We estimate the electrical conductivity of mantle silicates to be of the order of 100 Ω−1 cm−1, which implies that a magnetic dynamo process would develop in the magma oceans of Super-Earths if their convective velocities have typical values of 1 mm/s or higher. We predict exoplanets with rotation periods longer than 2 days to have multipolar magnetic fields.
Spatiotemporal dynamics of homologous recombination repair at single collapsed replication forks
Authors: Whelan Donna R. , Lee Wei Ting C. , Yin Yandong , Ofri Dylan M. , Bermudez-Hernandez Keria , Keegan Sarah , Fenyo David , Rothenberg Eli
Published: September 2018

Homologous recombination (HR) is a crucial pathway for the repair of DNA double-strand breaks. BRCA1/2 breast cancer proteins are key players in HR via their mediation of RAD51 nucleofilament formation and function; however, their individual roles and crosstalk in vivo are unknown. Here we use super-resolution (SR) imaging to map the spatiotemporal kinetics of HR proteins, revealing the interdependent relationships that govern the dynamic interplay and progression of repair events. We show that initial single-stranded DNA/RAD51 nucleofilament formation is mediated by RAD52 or, in the absence of RAD52, by BRCA2. In contrast, only BRCA2 can orchestrate later RAD51 recombinase activity during homology search and resolution. Furthermore, we establish that upstream BRCA1 activity is critical for BRCA2 function. Our analyses reveal the underlying epistatic landscape of RAD51 functional dependence on RAD52, BRCA1, and BRCA2 during HR and explain the phenotypic similarity of diseases associated with mutations in these proteins.
Structure of Type-I Mycobacterium tuberculosis fatty acid synthase at 3.3 Å resolution
Authors: Elad Nadav , Baron Szilvia , Peleg Yoav , Albeck Shira , Grunwald Jacob , Raviv Gal , Shakked Zippora , Zimhony Oren , Diskin Ron
Published: September 2018

Tuberculosis (TB) is a devastating and rapidly spreading disease caused by Mycobacterium tuberculosis (Mtb). Therapy requires prolonged treatment with a combination of multiple agents and interruptions in the treatment regimen result in emergence and spread of multi-drug resistant (MDR) Mtb strains. MDR Mtb poses a significant global health problem, calling for urgent development of novel drugs to combat TB. Here, we report the 3.3 Å resolution structure of the ~2 MDa type-I fatty acid synthase (FAS-I) from Mtb, determined by single particle cryo-EM. Mtb FAS-I is an essential enzymatic complex that contributes to the virulence of Mtb, and thus a prime target for anti-TB drugs. The structural information for Mtb FAS-I we have obtained enables computer-based drug discovery approaches, and the resolution achieved by cryo-EM is sufficient for elucidating inhibition mechanisms by putative small molecular weight inhibitors.
Retained free energy as a driving force for phase transformation during rapid solidification of stainless steel alloys in microgravity
Authors: Matson Douglas M.
Published: September 2018

Ternary Fe-Cr-Ni stainless steel alloys often exhibit a multi-step transformation known as double recalescence where primary ferrite converts to austenite during rapid solidification processes such as casting and welding. In addition to the volume free energy associated with undercooling between the phases, the free energy driving the transformation comes from two additional sources that are retained within the metastable solid—one from the primary phase undercooling and one from melt shear. A new physical model is proposed based on accumulation of defects, such as dislocations or tilt boundaries, and lattice strain. A dimensionless analysis technique shows that the free energy associated with metastable solidification is conserved and the contribution from melt shear can be predicted based on a modification of the Read-Shockley dislocation energy equation. With these additional terms the incubation time between nucleation events becomes inversely proportional to the total free energy squared for bulk diffusion and cubed for grain boundary diffusion mechanisms. In the case of the ferrous alloys studied, the grain boundary mechanism provides a better fit and when the model is applied the delay time behavior collapses to a single master-curve for the entire alloy family.
Commercial scale membrane distillation for solar desalination
Authors: Zaragoza G. , Andrés-Mañas J. A , Ruiz-Aguirre A.
Published: September 2018

Membrane distillation is an attractive technology for solar-powered decentralized desalination that has not yet reached commercial breakthrough on a large scale. The main barriers are energy consumption and cost. Since the latter are mostly related to the former, thermal energy efficiency is key to assessing the potential of the different available membrane distillation systems at a commercial scale. As discussed here, existing membrane distillation technologies use mostly flat sheet membranes in plate and frame and spiral-wound modules. Modules based on hollow fibre membranes are also considered, as well as the concept of multi-effect vacuum membrane distillation for improved heat recovery. The heat efficiency of each system is analysed based on available experimental results. Better internal heat recovery and capacity for upscaling are found to be important elements of distinction which make multi-channelled spiral-wound modules working in air-gap configuration stand out currently, with the lowest heat consumption of all large scale modules. Potential for improvement of this and other technologies is also discussed, and an estimation based on the associated costs for solar energy is used for establishing boundary conditions towards the implementation of membrane distillation for solar desalination.
Genome guided investigation of antibiotics producing actinomycetales strain isolated from a Macau mangrove ecosystem
Authors: Hu Dini , Chen Yan , Sun Chenghang , Jin Tao , Fan Guangyi , Liao Qiwen , Mok Kai Meng , Lee Ming-Yuen Simon
Published: September 2018

Actinomycetes are a heterogeneous group of gram positive filamentous bacteria that have been found to produce a wide range of valuable bioactive secondary metabolites, particularly antibiotics. Moreover, actinomycetes isolated from unexplored environments show an unprecedented potential to generate novel active compounds. Hence, in order to search for novel antibiotics, we isolated and characterized actinomycetes strains from plant samples collected from a mangrove in Macau. Within the class of actinobacteria, fourteen actinomycetes isolates have been isolated and identified belonging to the genus of Streptomyces, Micromonospora, Mycobacterium, Brevibacterium, Curtobacterium and Kineococcus based on their 16S rRNA sequences. Further whole genome sequencing analysis of one of the isolated Streptomyces sp., which presented 99.13% sequence similarity with Streptomyces parvulus strain 2297, showed that it consisted of 118 scaffolds, 8,348,559 base pairs and had a 72.28% G + C content. In addition, genome-mining revealed that the isolated Streptomyces sp. contains 109 gene clusters responsible for the biosynthesis of known and/or novel secondary metabolites, including different types of terpene, T1pks, T2pks, T3pks, Nrps, indole, siderophore, bacteriocin, thiopeptide, phosphonate, lanthipeptide, ectoine, butyrolactone, T3pks-Nrps, and T1pks-Nrps. Meanwhile, the small molecules present in ethyl acetate extract of the fermentation broth of this strain were analyzed by LC-MS. Predicted secondary metabolites of melanin and desferrioxamine B were identified and both of them were firstly found to be produced by the Streptomyces parvulus strain. Our study highlights that combining genome mining is an efficient method to detect potentially promising natural products from mangrove-derived actinomycetes.
Crystal structures of multicopper oxidase CueO G304K mutant: structural basis of the increased laccase activity
Authors: Wang Hanqian , Liu Xiaoqing , Zhao Jintong , Yue Qingxia , Yan Yuhua , Gao Zengqiang , Dong Yuhui , Zhang Zhiyong , Fan Yunliu , Tian Jian , Wu Ningfeng , Gong Yong
Published: September 2018

The multicopper oxidase CueO is involved in copper homeostasis and copper (Cu) tolerance in Escherichia coli. The laccase activity of CueO G304K mutant is higher than wild-type CueO. To explain this increase in activity, we solved the crystal structure of G304K mutant at 1.49 Å. Compared with wild-type CueO, the G304K mutant showed dramatic conformational changes in methionine-rich helix and the relative regulatory loop (R-loop). We further solved the structure of Cu-soaked enzyme, and found that the addition of Cu ions induced further conformational changes in the R-loop and methionine-rich helix as a result of the new Cu-binding sites on the enzyme’s surface. We propose a mechanism for the enhanced laccase activity of the G304K mutant, where movements of the R-loop combined with the changes of the methionine-rich region uncover the T1 Cu site allowing greater access of the substrate. Two of the G304K double mutants showed the enhanced or decreased laccase activity, providing further evidence for the interaction between the R-loop and the methionine-rich region. The cuprous oxidase activity of these mutants was about 20% that of wild-type CueO. These structural features of the G304K mutant provide clues for designing specific substrate-binding mutants in the biotechnological applications.
Tailoring diamond’s optical properties via direct femtosecond laser nanostructuring
Authors: Martínez-Calderon M. , Azkona J. J. , Casquero N. , Rodríguez A. , Domke Matthias , Gómez-Aranzadi M. , Olaizola S. M. , Granados E.
Published: September 2018

We demonstrate a rapid, accurate, and convenient method for tailoring the optical properties of diamond surfaces by employing laser induced periodic surface structuring (LIPSSs). The characteristics of the fabricated photonic surfaces were adjusted by tuning the laser wavelength, number of impinging pulses, angle of incidence and polarization state. Using Finite Difference Time Domain (FDTD) modeling, the optical transmissivity and bandwidth was calculated for each fabricated LIPSSs morphology. The highest transmission of ~99.5% was obtained in the near-IR for LIPSSs structures with aspect ratios of the order of ~0.65. The present technique enabled us to identify the main laser parameters involved in the machining process, and to control it with a high degree of accuracy in terms of structure periodicity, morphology and aspect ratio. We also demonstrate and study the conditions for fabricating spatially coherent nanostructures over large areas maintaining a high degree of nanostructure repeatability and optical performance. While our experimental demonstrations have been mainly focused on diamond anti-reflection coatings and gratings, the technique can be easily extended to other materials and applications, such as integrated photonic devices, high power diamond optics, or the construction of photonic surfaces with tailored characteristics in general.