bluuebunny/crossref_metadata_2025 huggingface dataset:
HCV Ag quantification as a one‐step procedure in diagnosing chronic hepatitis C infection in Cameroon: the ANRS 12336 study
Authors: Duchesne Léa , Njouom Richard , Lissock Frédéric , Tamko‐Mella Gishlaine Flore , Rallier Sandrine , Poiteau Lila , Soulier Alexandre , Chevaliez Stéphane , Vernet Guy , Rouveau Nicolas , Pawlotsky Jean‐Michel , Girard Pierre‐Marie , Lacombe Karine
Published: May 2017

Introduction: The diagnostic procedure for chronic hepatitis C infection (CHC) usually combines anti‐HCV antibody (HCV‐Ab) and HCV‐RNA measurement. Quantifying HCV core antigen (cAg) as a one‐step procedure could shorten the diagnostic process. We aimed to assess the performance of cAg quantification in diagnosing CHC and how it is influenced by concomitant HIV or HBV infections.

Methods: The cAg was quantified by an automated assay (Abbott Diagnostics) in 465 HCV‐Abnegative serum samples and 544 HCV‐RNA positive serum samples (n = 1009) collected in patients from the Pasteur Center in Cameroon, some of whom were infected by HBV or HIV. Its performance was evaluated in comparison to the gold standard (ELISA or PCR) by estimating its sensitivity (Se) and specificity (Sp), and by comparing the area under ROC (AUROC) curves in each patient population: HCV mono‐infected, HCV‐HBV and HIV‐HCV co‐infected.

Results: Among the 465 HCV‐Abnegative patients, 51 and 79 were HIV‐ and HBV‐infected, respectively, whereas among the 544 patients with CHC, 27 and 28 were HIV‐ and HBV‐infected, respectively. The Spearmanρcorrelation coefficient between cAg and HCV‐RNA was 0.75 (p < 0.00001). The assay had a sensitivity of 95.7% (95% CI: 93.2–97.5) and a specificity of 99.7% (95% CI: 98.1–10) in diagnosing CHC, corresponding to an AUROC of 0.99 (95% CI: 0.98–1.0). Being HIV‐ or HBV‐infected did not impact the performance of cAg (Se = 96.4%, Sp = 96.2% and AUROC = 0.98 (95% CI: 0.95–1.0) in the HBV group, Se = 100%, Sp = 88.2% and AUROC = 0.99 (95% CI: 0.97–1.0) in the HIV group,pbetween AUROC = 0.69).

Conclusions: The cAg quantification displayed a high specificity and sensitivity for the diagnosis of CHC in Cameroon, and its performance was not significantly modified by a concomitant HIV or HBV infection. In the context of CHC elimination on a global scale, using cAg quantification as a screening tool to directly identify CHC could be a reliable tool in a “test and treat” strategy.
Examining the effects of HIV self‐testing compared to standard HIV testing services: a systematic review and meta‐analysis
Authors: Johnson Cheryl C , Kennedy Caitlin , Fonner Virginia , Siegfried Nandi , Figueroa Carmen , Dalal Shona , Sands Anita , Baggaley Rachel
Published: May 2017

Introduction: HIV self‐testing (HIVST) is a discreet and convenient way to reach people with HIV who do not know their status, including many who may not otherwise test. To inform World Health Organization (WHO) guidance, we assessed the effect of HIVST on uptake and frequency of testing, as well as identification of HIV‐positive persons, linkage to care, social harm, and risk behaviour.

Methods: We systematically searched for studies comparing HIVST to standard HIV testing until 1 June 2016. Meta‐analyses of studies reporting comparable outcomes were conducted using a random‐effects model for relative risks (RR) and 95% confidence intervals. The quality of evidence was evaluated using GRADE.

Results: After screening 638 citations, we identified five randomized controlled trials (RCTs) comparing HIVST to standard HIV testing services among 4,145 total participants from four countries. All offered free oral‐fluid rapid tests for HIVST and were among men. Meta‐analysis of three RCTs showed HIVST doubled uptake of testing among men (RR = 2.12; 95% CI: 1.51, 2.98). Meta‐analysis of two RCTs among men who have sex with men showed frequency of testing nearly doubled (Rate ratio = 1.88; 95% CI: 1.17; 3.01), resulting in two more tests in a 12–15‐month period (Mean difference = 2.13; 95% CI: 1.59, 2.66). Meta‐analysis of two RCTs showed HIVST also doubled the likelihood of an HIV‐positive diagnosis (RR = 2.02; 95% CI: 0.37, 10.76, 5.32). Across all RCTs, there was no indication of harm attributable to HIVST and potential increases in risk‐taking behaviour appeared to be minimal.

Conclusions: HIVST is associated with increased uptake and frequency of testing in RCTs. Such increases, particularly among those at risk who may not otherwise test, will likely identify more HIV‐positive individuals as compared to standard testing services alone. However, further research on how to support linkage to confirmatory testing, prevention, treatment and care services is needed. WHO now recommends HIVST as an additional HIV testing approach.
HIV healthcare transition outcomes among youth in North America and Europe: a review
Authors: Tepper Vicki , Zaner Stefanie , Ryscavage Patrick
Published: May 2017

Introduction: The transition from paediatric to adult care poses risks to the health of young adults living with HIV if unsuccessful, including interruptions in care and poor health outcomes. Evolving best practices in HIV healthcare transition should ideally be informed by real‐world qualitative and quantitative clinical healthcare transition outcomes. There has been a recent proliferation of HIV healthcare transition outcome research, largely from Europe and North America.

Methods: A literature search was undertaken using the online databases PubMed, Web of Science, and Google Scholar. Medical subject and text word searches were combined for terms relating to HIV, paediatric transition outcomes, and internal and external factors were used to identify peer‐reviewed articles.

Results: In this paper, we review data on HIV healthcare transition outcomes in North America and Europe. Internal and external factors which may impact the success of HIV healthcare transition are examined. We describe ongoing research efforts to capture transition outcomes in the North America and Europe. Clinical, operational, and implementation science research gaps that exist to date are highlighted. Efforts to improve HIV healthcare transition research through country‐level surveillance networks and large multicentre cohorts, including data integration and linkage between paediatric and adult cohorts are discussed.

Conclusions: We identified the need for a comprehensive approach to implementing empirically supported protocols to support healthcare transition for ALHIV. While there is limited prospective longitudinal cohort data available at this time, cohorts linking the paediatric and adolescent with ongoing surveillance into adulthood are being developed. Through a review of existing qualitative and quantitative healthcare transition outcomes studies, we identify emerging areas of consensus surrounding healthcare transition research implementation. Successful healthcare transition programmes in Europe and North America often share several characteristics, including implementation of a youth friendly multidisciplinary approach, consistent communication and integration between paediatric and adult care teams, and an individualized approach which is attuned the adolescent's transition readiness. Moving forward, the voices of youth and young adults living with HIV should be included in the development and evaluation of healthcare transition protocols to ensure that the definition of successful transition reflects all of the stakeholders in the transition process.
Living and dying to be counted: What we know about the epidemiology of the global adolescent HIV epidemic
Authors: Slogrove Amy L. , Mahy Mary , Armstrong Alice , Davies Mary‐Ann
Published: May 2017

Introduction: With increasing survival of vertically HIV‐infected children and ongoing new horizontal HIV infections, the population of adolescents (age 10–19 years) living with HIV is increasing. This review aims to describe the epidemiology of the adolescent HIV epidemic and the ability of national monitoring systems to measure outcomes in HIV‐infected adolescents through the adolescent transition to adulthood.

Methods: Differences in global trends between younger (age 10–14 years) and older (age 15–19 years) adolescents in key epidemic indicators are interrogated using 2016 UNAIDS estimates. National population‐based survey data in the 15 highest adolescent HIV burden countries are evaluated and examples of national case‐based surveillance systems described. Finally, we consider the potential impact of adolescent‐specific recommendations in the 2016 WHO Consolidated Guidelines on the Use of Antiretroviral Drugs for Treating and Preventing HIV Infection.

Discussion: UNAIDS estimates indicate the population of adolescents living with HIV is increasing, new HIV infections in older adolescents are declining, and while AIDS‐related deaths are beginning to decline in younger adolescents, they are still increasing in older adolescents. National population‐based surveys provide valuable estimates of HIV prevalence in older adolescents and recent surveys include data on younger adolescents. Only a few countries have nationwide electronic case‐based HIV surveillance, with the ability to provide population‐level data on key HIV outcomes in the diagnosed population living with HIV. However, in the 15 highest adolescent HIV burden countries, there are no systems tracking adolescent transition to adulthood or healthcare transition. The strength of the 2016 WHO adolescent‐specific recommendations on antiretroviral therapy and provision of HIV services to adolescents was hampered by the lack of evidence specific to this age group.

Conclusions: Progress is being made in national surveillance and global monitoring systems to specifically identify trends in adolescents living with HIV. However, HIV programmes responsive to the evolving HIV prevention and treatment needs of adolescents can be facilitated further by: data disaggregation to younger and older adolescents and mode of HIV infection where feasible; implementation of tools to achieve expanded national case‐based surveillance; streamlining consent/assent procedures in younger adolescents and consensus on indicators of adolescent healthcare transition and transition to adulthood.
In-Shoe Plantar Pressure Profiles in Amateur Basketball Players
Authors: Kong Pui W. , Lam Wing K. , Ng Wei X. , Aziz Luqman , Leong Hin F.
Published: May 2017

Background:

Biomechanical analysis of foot loading characteristics may provide insights into the injury mechanisms and guide orthotic prescription for basketball players. This study aimed to quantify in-shoe plantar pressure profiles in amateur players when executing typical basketball movements.

Methods:

Twenty male university basketball players performed four basketball-specific movement tasks—running, maximal forward sprinting, maximal 45° cutting, and layup—in a pair of standardized basketball shoes fitted with an in-shoe plantar pressure measurement system. Peak pressure (PP) and pressure-time integral (PTI) data were extracted from ten plantar regions. One-way repeated-measures analysis of variance was performed across the tasks, with significance set at P < .05.

Results:

Distinct plantar pressure distribution patterns were observed among the four movements. Compared with running, significantly higher (P < .05) PP and PTI of up to approximately 55% were found in sprinting and layup, particularly at the forefoot region. Similarly, significantly higher (P < .05) PPs and PTIs, ranging from approximately 23% to 90%, were observed in 45° cutting compared with running at most foot regions.

Conclusions:

Compared with running, sprinting and layup demonstrated higher plantar loading in the forefoot region, and 45° cutting yielded increased plantar loading in most regions of the foot. Understanding the plantar pressure characteristics of different movements may be useful in optimizing footwear designs, orthosis use, or training strategies to minimize regional plantar loading during amateur basketball play.
Distributing tasks via multiple input pathways increases cellular survival in stress
Authors: Granados Alejandro A , Crane Matthew M , Montano-Gutierrez Luis F , Tanaka Reiko J , Voliotis Margaritis , Swain Peter S
Published: May 2017

Improving in one aspect of a task can undermine performance in another, but how such opposing demands play out in single cells and impact on fitness is mostly unknown. Here we study budding yeast in dynamic environments of hyperosmotic stress and show how the corresponding signalling network increases cellular survival both by assigning the requirements of high response speed and high response accuracy to two separate input pathways and by having these pathways interact to converge on Hog1, a p38 MAP kinase. Cells with only the less accurate, reflex-like pathway are fitter in sudden stress, whereas cells with only the slow, more accurate pathway are fitter in increasing but fluctuating stress. Our results demonstrate that cellular signalling is vulnerable to trade-offs in performance, but that these trade-offs can be mitigated by assigning the opposing tasks to different signalling subnetworks. Such division of labour could function broadly within cellular signal transduction.
Opening Up Communication: Assessing Open Access Practices in the Communication Studies Discipline
Authors: Schultz Teresa Auch
Published: May 2017

INTRODUCTION Open access (OA) citation effect studies have looked at a number of disciplines but not yet the field of communication studies. This study researched how communication studies fare with the open access citation effect, as well as whether researchers follow their journal deposit policies. METHOD The study tracked 920 articles published in 2011 and 2012 from 10 journals and then searched for citations and an OA version using the program Publish or Perish. Deposit policies of each of the journals were gathered from SHERPA/RoMEO and used to evaluate OA versions. RESULTS From the sample, 42 percent had OA versions available. Of those OA articles, 363 appeared to violate publisher deposit policies by depositing the version of record, but the study failed to identify post-print versions for 87 percent of the total sample for the journals that allowed it. All articles with an OA version had a median of 17 citations, compared to only nine citations for non-OA articles. DISCUSSION & CONCLUSION The citation averages, which are statistically significant, show a positive correlation between OA and the number of citations. The study also shows communication studies researchers are taking part in open access but perhaps without the full understanding of their publisher’s policies.
Preservation media, durations and cell concentrations of short-term storage affect key features of human adipose-derived mesenchymal stem cells for therapeutic application
Authors: Zhang Fengli , Ren Huaijuan , Shao Xiaohu , Zhuang Chao , Chen Yantian , Qi Nianmin
Published: May 2017

Background

Adipose-derived mesenchymal stem cells (ADSCs) have shown great potential in the treatment of various diseases. However, the optimum short-term storage condition of ADSCs in 2∼8 °C is rarely reported. This study aimed at optimizing a short-term storage condition to ensure the viability and function of ADSCs before transplantation.

Methods

Preservation media and durations of storage were evaluated by cell viability, apoptosis, adhesion ability and colony-forming unit (CFU) capacity of ADSCs. The abilities of cell proliferation and differentiation were used to optimize cell concentrations. Optimized preservation condition was evaluated by cell surface markers, cell cycle and immunosuppressive capacity.

Results

A total of 5% human serum albumin in multiple electrolytes (ME + HSA) was the optimized medium with high cell viability, low cluster rate, good adhesion ability and high CFU capacity of ADSCs. Duration of storage should be limited to 24 h to ensure the quality of ADSCs before transplantation. A concentration of 5 × 106cells/ml was the most suitable cell concentration with low late stage apoptosis, rapid proliferation and good osteogenic and adipogenic differentiation ability. This selected condition did not change surface markers, cell cycle, indoleamine 2, 3-dioxygenase 1 (IDO1) gene expression and kynurenine (Kyn) concentration significantly.

Discussion

In this study, ME + HSA was found to be the best medium, most likely due to the supplement of HSA which could protect cells, the physiological pH (7.4) of ME and sodium gluconate ingredient in ME which could provide energy for cells. Duration should be limited to 24 h because of reduced nutrient supply and increased waste and lactic acid accumulation during prolonged storage. To keep cell proliferation and limit lactic acid accumulation, the proper cell concentration is 5× 106cells/ml. Surface markers, cell cycle and immunosuppressive capacity did not change significantly after storage using the optimized condition, which confirmed our results that this optimized short-term storage condition of MSCs has a great potential for the application of cell therapy.
Dietary flavonoids of Spanish youth: intakes, sources, and association with the Mediterranean diet
Authors: Bawaked Rowaedh Ahmed , Schröder Helmut , Barba Lourdes Ribas , Cárdenas Gabriela , Peña-Quintana Luis , Rodrigo Carmen Pérez , Fíto Montserrat , Majem Lluis Serra
Published: May 2017

Background

Plant-based diets have been linked to high diet quality and reduced risk of cardiovascular diseases. The health impact of plant-based diets might be partially explained by the concomitant intake of flavonoids. Estimation of flavonoids intake in adults has been important for the development of dietary recommendations and interventions for the prevention of weight gain and its consequences. However, estimation of flavonoids intake in children and adolescents is limited.

Methods

Average daily intake and sources of flavonoids were estimated for a representative national sample of 3,534 children and young people in Spain, aged 2–24 years. The data was collected between 1998 and 2000 by 24-h recalls. The Phenol-Explorer database and the USDA database on flavonoids content were used. Adherence to the Mediterranean diet was measured by the KIDMED index.

Results

The mean and median intakes of total flavonoids were 70.7 and 48.1 mg/day, respectively. The most abundant flavonoid class was flavan-3-ols (35.7%), with fruit being the top food source of flavonoids intake (42.8%). Total flavonoids intake was positively associated with the KIDMED index (p < 0.001).

Conclusion

The results of this study provide primary information about flavonoids intake and main food sources in Spanish children, adolescents and young adults. Participants with high daily mean intake of flavonoids have higher adherence to the Mediterranean diet.
Characterisation of false-positive observations in botanical surveys
Authors: Groom Quentin J. , Whild Sarah J.
Published: May 2017

Errors in botanical surveying are a common problem. The presence of a species is easily overlooked, leading to false-absences; while misidentifications and other mistakes lead to false-positive observations. While it is common knowledge that these errors occur, there are few data that can be used to quantify and describe these errors. Here we characterise false-positive errors for a controlled set of surveys conducted as part of a field identification test of botanical skill. Surveys were conducted at sites with a verified list of vascular plant species. The candidates were asked to list all the species they could identify in a defined botanically rich area. They were told beforehand that their final score would be the sum of the correct species they listed, but false-positive errors counted against their overall grade. The number of errors varied considerably between people, some people create a high proportion of false-positive errors, but these are scattered across all skill levels. Therefore, a person’s ability to correctly identify a large number of species is not a safeguard against the generation of false-positive errors. There was no phylogenetic pattern to falsely observed species; however, rare species are more likely to be false-positive as are species from species rich genera. Raising the threshold for the acceptance of an observation reduced false-positive observations dramatically, but at the expense of more false negative errors. False-positive errors are higher in field surveying of plants than many people may appreciate. Greater stringency is required before accepting species as present at a site, particularly for rare species. Combining multiple surveys resolves the problem, but requires a considerable increase in effort to achieve the same sensitivity as a single survey. Therefore, other methods should be used to raise the threshold for the acceptance of a species. For example, digital data input systems that can verify, feedback and inform the user are likely to reduce false-positive errors significantly.
The limits to global‐warming mitigation by terrestrial carbon removal
Authors: Boysen Lena R. , Lucht Wolfgang , Gerten Dieter , Heck Vera , Lenton Timothy M. , Schellnhuber Hans Joachim
Published: May 2017

Massive near‐term greenhouse gas emissions reduction is a precondition for staying “well below 2°C” global warming as envisaged by the Paris Agreement. Furthermore, extensive terrestrial carbon dioxide removal (tCDR) through managed biomass growth and subsequent carbon capture and storage is required to avoid temperature “overshoot” in most pertinent scenarios. Here, we address two major issues: First, we calculate the extent of tCDR required to “repair” delayed or insufficient emissions reduction policies unable to prevent global mean temperature rise of 2.5°C or even 4.5°C above pre‐industrial level. Our results show that those tCDR measures are unable to counteract “business‐as‐usual” emissions without eliminating virtually all natural ecosystems. Even if considerable (Representative Concentration Pathway 4.5 [RCP4.5]) emissions reductions are assumed, tCDR with 50% storage efficiency requires >1.1 Gha of the most productive agricultural areas or the elimination of >50% of natural forests. In addition, >100 MtN/yr fertilizers would be needed to remove the roughly 320 GtC foreseen in these scenarios. Such interventions would severely compromise food production and/or biosphere functioning. Second, we reanalyze the requirements for achieving the 160–190 GtC tCDR that would complement strong mitigation action (RCP2.6) in order to avoid 2°C overshoot anytime. We find that a combination of high irrigation water input and/or more efficient conversion to stored carbon is necessary. In the face of severe trade‐offs with society and the biosphere, we conclude that large‐scale tCDR is not a viable alternative to aggressive emissions reduction. However, we argue that tCDR might serve as a valuable “supporting actor” for strong mitigation if sustainable schemes are established immediately.
Multi‐model and multi‐scenario assessments of Asian water futures: The Water Futures and Solutions (WFaS) initiative
Authors: Satoh Yusuke , Kahil Taher , Byers Edward , Burek Peter , Fischer Günther , Tramberend Sylvia , Greve Peter , Flörke Martina , Eisner Stephanie , Hanasaki Naota , Magnuszewski Piotr , Nava Luzma Fabiola , Cosgrove William , Langan Simon , Wada Yoshihide
Published: May 2017

This paper presents one of the first quantitative scenario assessments for future water supply and demand in Asia to 2050. The assessment, developed by the Water Futures and Solutions (WFaS) initiative, uses the latest set of global climate change and socioeconomic scenarios and state‐of‐the‐art global hydrological models. In Asia, water demand for irrigation, industry, and households is projected to increase substantially in the coming decades (30–40% by 2050 compared to 2010). These changes are expected to exacerbate water stress, especially in the current hotspots such as north India and Pakistan, and north China. By 2050, 20% of the land area in the Asia‐Pacific region, with a population of 1.6–2 billion, is projected to experience severe water stress. We find that socioeconomic changes are the main drivers of worsening water scarcity in Asia, with climate change impacts further increasing the challenge into the 21st century. Moreover, a detailed basin‐level analysis of the hydro‐economic conditions of 40 Asian basins shows that although the coping capacity of all basins is expected to improve due to gross domestic product (GDP) growth, some basins continuously face severe water challenges. These basins will potentially be home to up to 1.6 billion people by mid‐21st century.
Understanding the weather signal in national crop‐yield variability
Authors: Frieler Katja , Schauberger Bernhard , Arneth Almut , Balkovič Juraj , Chryssanthacopoulos James , Deryng Delphine , Elliott Joshua , Folberth Christian , Khabarov Nikolay , Müller Christoph , Olin Stefan , Pugh Thomas A. M. , Schaphoff Sibyll , Schewe Jacob , Schmid Erwin , Warszawski Lila , Levermann Anders
Published: May 2017

Year‐to‐year variations in crop yields can have major impacts on the livelihoods of subsistence farmers and may trigger significant global price fluctuations, with severe consequences for people in developing countries. Fluctuations can be induced by weather conditions, management decisions, weeds, diseases, and pests. Although an explicit quantification and deeper understanding of weather‐induced crop‐yield variability is essential for adaptation strategies, so far it has only been addressed by empirical models. Here, we provide conservative estimates of the fraction of reported national yield variabilities that can be attributed to weather by state‐of‐the‐art, process‐based crop model simulations. We find that observed weather variations can explain more than 50% of the variability in wheat yields in Australia, Canada, Spain, Hungary, and Romania. For maize, weather sensitivities exceed 50% in seven countries, including the United States. The explained variance exceeds 50% for rice in Japan and South Korea and for soy in Argentina. Avoiding water stress by simulating yields assuming full irrigation shows that water limitation is a major driver of the observed variations in most of these countries. Identifying the mechanisms leading to crop‐yield fluctuations is not only fundamental for dampening fluctuations, but is also important in the context of the debate on the attribution of loss and damage to climate change. Since process‐based crop models not only account for weather influences on crop yields, but also provide options to represent human‐management measures, they could become essential tools for differentiating these drivers, and for exploring options to reduce future yield fluctuations.
The effects of spacecraft charging and outgassing on the LADEE ion measurements
Authors: Xie Lianghai , Zhang Xiaoping , Zheng Yongchun , Guo Dawei
Published: May 2017

Abnormal ion signals can be usually seen in the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, including a suddenly enhanced current observed by the Lunar Dust Experiment (LDEX) near the sunlight‐shadow boundary and an unexpected water ion measured by the neutral mass spectrometer (NMS), with their magnitudes insensitive to the convection electric field of solar wind but dependent on the SW density and the elapsed time of LADEE mission. By analyzing both the LDEX measurements and the NMS measurements, we find that the current enhancement can be caused by a negatively charged spacecraft in the shadow region while the significant water ions should be some artificial ions from spacecraft outgassing. The artificial water ions show a peak near 8:00 LT that may be related to a sunlight‐controlled surface outgassing. In addition, the H2O flux can be enhanced near the end of the mission when the spacecraft has a lower altitude. It is found that the H2O enhancement is actually caused by an exosphere‐contributed return flux, rather than a real water exosphere.
Auroral precipitating energy during long magnetic storms
Authors: Cardoso F. R. , Alves M. V. , Parks G. K. , Fillingim M. O. , Simões Junior F. J. R. , Costa Junior E. , Koga D.
Published: May 2017

The power energy input carried by precipitating electrons into the auroral zone is an important parameter for understanding the solar wind‐magnetosphere energy transfer processes and magnetic storms triggering. Some magnetic storms present a peculiar long recovery phase, lasting for many days or even weeks, which can be associated with the intense and long‐duration auroral activity named HILDCAA (High Intensity Long Duration Continuous AE Activity). The auroral energy input during HILDCAAs has been pointed out as an essential key issue, although there have been very few quantitative studies on this topic. In the present work, we have estimated the auroral electron precipitating energy during the events of long (LRP) and short (SRP) storm recovery phase. The energy has been calculated from the images produced by the Ultraviolet Imager (UVI) on board the Polar satellite. In order to obtain accurate energy values, we developed a dayglow estimate method to remove solar contamination from the UVI images, before calculating the energy. We compared the UVI estimate to the Hemispheric Power (HP), to the empirical power obtained from the AE index, and to the solar wind input power. Our results showed that the UVI electron precipitating power for the LRP events presented a quasiperiodic fluctuation, which has been confirmed by the other estimates. We found that the LRP events are a consequence of a directly driven system, where there is no long‐term energy storage in the magnetosphere, and the auroral electrojets during these events are directly affected by the electron precipitating power.
Modification of sea surface temperature by chlorophyll concentration in the Atlantic upwelling systems
Authors: Hernandez O. , Jouanno J. , Echevin V. , Aumont O.
Published: May 2017

The influence of the chlorophyll on the upper Tropical Atlantic Ocean is investigated with long‐term (1979–2012) regional oceanic simulations with 1/4° horizontal resolution based on the NEMO3.6 model. The model solar radiation penetration scheme depends on the chlorophyll concentration. Simulations with time and spatially varying concentrations obtained from satellite ocean color observations are compared with a simulation forced with constant chlorophyll concentration of 0.05 mg m−3, representative of chlorophyll depleted waters. Results indicate that regions of the Tropical Atlantic with chlorophyll concentrations larger than in the reference simulation (i.e., [chl] > 0.05 mg m−3) get warmer at the surface, with the exception of the main upwelling regions where high chlorophyll concentrations are associated with a significant cooling of the sea surface (∼1°C in the Benguela upwelling). The analysis of the model heat balance shows that the biological differential heating causes negative temperature anomalies in subsurface source waters prior to their upwelling at the coast. The shallow mixed‐layer in the eastern equatorial and tropical Atlantic favors the persistence of these subsurface anomalies and may explain why the Benguela is particularly sensitive to the biological differential heating. In spite of the presence of high chlorophyll concentrations in the upwelling regions, both the larger amount of shortwave radiation captured in the surface layers and the modifications of the horizontal and vertical advection at the coast are found to play a secondary role in the SST change in the upwelling region.
The role of turbulence in thunderstorm, snowstorm, and dust storm electrification
Authors: Mareev Evgeny A. , Dementyeva Svetlana O.
Published: May 2017

In this paper the contribution of turbulence into the electrification of thunderstorms, snowstorms, and dust storms is investigated for the first time. A model of large‐scale electric field generation in a weakly conducting medium, containing two types of particles charging by collisions, is used. Thunderstorm and snowstorm electrification are considered in detail in this paper; dust storm electrification is also considered, despite being substantially different from the two other cases, to demonstrate the universality of the proposed method. A comparison of the results with the experimental data for thunderstorms, blizzards, and dust storms is carried out. It is found that the situation is notably different for inductive and noninductive charge separations. For inductive charge separation there is a range of thunderstorm and snowstorm parameters (conductivity and the particle radii being the most important factors) for which the electric field grows exponentially with time. This effect can make the inductive mechanism dominant near the breakdown field in turbulent zones of thunderclouds. For noninductive (or triboelectric) charge separation caused by intense velocity fluctuations, the electric field strength grows only linearly with time. The most substantial effect of turbulence on noninductive charging is expected to occur in snowstorms and dust storms, whereas noninductive turbulent charging has a little impact on the thunderstorm electrification.
A cloud‐resolving model study of aerosol‐cloud correlation in a pristine maritime environment
Authors: Nishant Nidhi , Sherwood Steven C.
Published: May 2017

In convective clouds, satellite‐observed deepening or increased amount of clouds with increasing aerosol concentration has been reported and is sometimes interpreted as aerosol‐induced invigoration of the clouds. However, such correlations can be affected by meteorological factors that affect both aerosol and clouds, as well as observational issues. In this study, we examine the behavior in a 660 × 660 km2 region of the South Pacific during June 2007, previously found by Koren et al. (2014) to show strong correlation between cloud fraction, cloud top pressure, and aerosols, using a cloud‐resolving model with meteorological boundary conditions specified from a reanalysis. The model assumes constant aerosol loading, yet reproduces vigorous clouds at times of high real‐world aerosol concentrations. Days with high‐ and low‐aerosol loading exhibit deep‐convective and shallow clouds, respectively, in both observations and the simulation. Synoptic analysis shows that vigorous clouds occur at times of strong surface troughs, which are associated with high winds and advection of boundary layer air from the Southern Ocean where sea‐salt aerosol is abundant, thus accounting for the high correlation. Our model results show that aerosol‐cloud relationships can be explained by coexisting but independent wind‐aerosol and wind‐cloud relationships and that no cloud condensation nuclei effect is required.
Isostatic equilibrium in spherical coordinates and implications for crustal thickness on the Moon, Mars, Enceladus, and elsewhere
Authors: Hemingway Douglas J. , Matsuyama Isamu
Published: May 2017

Isostatic equilibrium is commonly defined as the state achieved when there are no lateral gradients in hydrostatic pressure, and thus no lateral flow, at depth within the lower viscosity mantle that underlies a planetary body's outer crust. In a constant‐gravity Cartesian framework, this definition is equivalent to the requirement that columns of equal width contain equal masses. Here we show, however, that this equivalence breaks down when the spherical geometry of the problem is taken into account. Imposing the “equal masses” requirement in a spherical geometry, as is commonly done in the literature, leads to significant lateral pressure gradients along internal equipotential surfaces and thus corresponds to a state of disequilibrium. Compared with the “equal pressures” model we present here, the equal masses model always overestimates the compensation depth—by ∼27% in the case of the lunar highlands and by nearly a factor of 2 in the case of Enceladus.
Scale‐free distribution of Dead Sea sinkholes: Observations and modeling
Authors: Yizhaq H. , Ish‐Shalom C. , Raz E. , Ashkenazy Y.
Published: May 2017

There are currently more than 5500 sinkholes along the Dead Sea in Israel. These were formed due to the dissolution of subsurface salt layers as a result of the replacement of hypersaline groundwater by fresh brackish groundwater. This process has been associated with a sharp decline in the Dead Sea water level, currently more than 1 m/yr, resulting in a lower water table that has allowed the intrusion of fresher brackish water. We studied the distribution of the sinkhole sizes and found that it is scale free with a power law exponent close to 2. We constructed a stochastic cellular automata model to understand the observed scale‐free behavior and the growth of the sinkhole area in time. The model consists of a lower salt layer and an upper soil layer in which cavities that develop in the lower layer lead to collapses in the upper layer. The model reproduces the observed power law distribution without involving the threshold behavior commonly associated with criticality.
Internal variability in a coupled general circulation model in radiative‐convective equilibrium
Authors: Coppin David , Bony Sandrine
Published: May 2017

Numerical models run in non‐rotating radiative‐convective equilibrium (RCE) using prescribed sea surface temperatures (SSTs) show that convection can spontaneously aggregate into dry and moist areas, and that convective aggregation tends to increase with temperature. Using a general circulation model coupled to an ocean mixed layer, we show that in RCE the coupled ocean‐atmosphere system exhibits some internal variability. This variability arises from the interplay between mean surface temperature, SST gradients and convective aggregation, and its timescale is proportional to the depth of the ocean mixed layer. For an ocean layer deeper than 10 m, the variability occurs at the interannual timescale, and variations of convective aggregation are almost out of phase with those of surface temperature. The coupled RCE framework might be relevant to understand some internal modes of variability of the tropical ocean‐atmosphere system such as El Niño Southern Oscillation.
Electron‐acoustic solitons and double layers in the inner magnetosphere
Authors: Vasko I. Y. , Agapitov O. V. , Mozer F. S. , Bonnell J. W. , Artemyev A. V. , Krasnoselskikh V. V. , Reeves G. , Hospodarsky G.
Published: May 2017

The Van Allen Probes observe generally two types of electrostatic solitary waves (ESW) contributing to the broadband electrostatic wave activity in the nightside inner magnetosphere. ESW with symmetric bipolar parallel electric field are electron phase space holes. The nature of ESW with asymmetric bipolar (and almost unipolar) parallel electric field has remained puzzling. To address their nature, we consider a particular event observed by Van Allen Probes to argue that during the broadband wave activity electrons with energy above 200 eV provide the dominant contribution to the total electron density, while the density of cold electrons (below a few eV) is less than a few tenths of the total electron density. We show that velocities of the asymmetric ESW are close to velocity of electron‐acoustic waves (existing due to the presence of cold and hot electrons) and follow the Korteweg‐de Vries (KdV) dispersion relation derived for the observed plasma conditions (electron energy spectrum is a power law between about 100 eV and 10 keV and Maxwellian above 10 keV). The ESW spatial scales are in general agreement with the KdV theory. We interpret the asymmetric ESW in terms of electron‐acoustic solitons and double layers (shocks waves).
Small‐scale longitudinal variations in the daytime equatorial thermospheric wave dynamics as inferred from oxygen dayglow emissions
Authors: Karan Deepak K. , Pallamraju Duggirala
Published: May 2017

The equatorial upper atmospheric dynamic processes show both latitudinal and longitudinal variabilities. While the variability in latitudes can exist over small distances (approximately hundreds of kilometers), the longitudinal behavior has been shown to be existing mainly over large spatial separations (approximately thousands of kilometers). In the present work we have used variations in thermospheric optical dayglow emissions at OI 557.7, 630.0, and 777.4 nm, as tracers of neutral dynamics. These emissions are obtained simultaneously from a high‐resolution slit spectrograph, Multi wavelength Imaging Spectrograph using Echelle grating, from a low‐latitude location, Hyderabad (17.5°N, 78.4°E; 8.9°N magnetic latitude) in India, to investigate the longitudinal differences in the upper atmospheric processes over short separations. Spectral analyses of gravity waves carried out on the dayglow emission intensity variations for different independent viewing directions on some days show dissimilar periodicities suggesting the existence of longitudinal differences. Gravity wave scale sizes and the propagation characteristics on these days are different from those in which longitudinal differences are not seen. Further, the zenith diurnal emission intensity patterns are different on the days with and without the observed longitudinal variability. This work shows for the first time that longitudinal differences in upper atmospheric processes can exist at even as small as 3° longitude separations. Such longitudinal differences seen in the neutral dayglow emission intensities are attributed to the zonal variation in the daytime equatorial electrodynamics.
Ion Bernstein instability as a possible source for oxygen ion cyclotron harmonic waves
Authors: Min Kyungguk , Denton Richard E. , Liu Kaijun , Gary S. Peter , Spence Harlan E.
Published: May 2017

This paper demonstrates that an ion Bernstein instability can be a possible source for recently reported electromagnetic waves with frequencies at or near the singly ionized oxygen ion cyclotron frequency,
, and its harmonics. The particle measurements during strong wave activity revealed a relatively high concentration of oxygen ions (∼15%) whose phase space density exhibits a local peak at energy ∼20 keV. Given that the electron plasma‐to‐cyclotron frequency ratio is
, this energy corresponds to the particle speed
, where vA is the oxygen Alfvén speed. Using the observational key plasma parameters, a simplified ion velocity distribution is constructed, where the local peak in the oxygen ion velocity distribution is represented by an isotropic shell distribution. Kinetic linear dispersion theory then predicts unstable Bernstein modes at or near the harmonics of
and at propagation quasi‐perpendicular to the background magnetic field, B0. If the cold ions are mostly protons, these unstable modes are characterized by a low compressibility (
), a small phase speed (vph∼0.2vA), a relatively small ratio of the electric field energy to the magnetic field energy (between 10−4 and 10−3), and the Poynting vector directed almost parallel to B0. These linear properties are overall in good agreement with the properties of the observed waves. We demonstrate that superposition of the predicted unstable Bernstein modes at quasi‐perpendicular propagation can produce the observed polarization properties, including the minimum variance direction on average almost parallel to B0.
Enzymatic Modification of Plant Cell Wall Polysaccharides
Authors: Øbro Jens , Hayashi Takahisa , Mikkelsen Jørn Dalgaard
Published: May 2017

Plant cell walls are intricate structures with remarkable properties, widely used in almost every aspect of our life. Cell walls consist largely of complex polysaccharides and there is often a need for chemical and biochemical processing before industrial use. There is an increasing demand for sustainable processes that replace chemical treatments with white biotechnology. Plants can contribute significantly to this sustainable process by producing plant or microbial enzymesin plantathat are necessary for plant cell wall modification or total degradation. This will give rise to superior food fibres, hydrocolloids, paper, textile, animal feeds or biofuels. Classical microbial‐based fermentation systems could in the future face serious competition from plant‐based expression systems for enzyme production. Plant expressed enzymes can either be targeted to specific cellular compartments for accumulation and storage, or targeted to the cell wall for immediate modification of the polysaccharides. Furthermore, thermoactivated enzymes can successfully be employed to avoid undue degradation of the cell wall and detrimental phenotypes resulting from this. A further use of enzyme expressionin plantais the possibility of elucidating the biological role of specific polymers, such as the involvement of xyloglucan in tree bending, or to decrease the level of pectin in flax to simplify the retting step in the textile refinery process.
100 Years of Ethylene – A Personal View
Authors: Grierson Don
Published: May 2017

During the last 100 years, our view of ethylene has progressed from it being an environmental factor with profound effects on plants to an endogenous plant hormone controlling growth, development and reproduction. The ethylene story began with the work of Neljubov, a Russian graduate student. Previous work had indicated the adverse effect of illuminating gas on trees, but Neljubov (1901) was the first to describe the triple growth response of etiolated pea seedlings: (1) reduced stature, (2) exaggerated hypocotyl hook and (3) inhibited root growth (see Figure 1), which was subsequently shown to be due to hydrocarbons such as ethylene in the illuminating gas. When the method of heating banana‐ripening rooms was switched from coke ovens to electric arc furnaces, it was noted that the fruit did not ripen so effectively, and it was eventually realized that the production of ethylene and other hydrocarbons during the combustion of coke actually stimulated ripening of the fruit. Later, it was found that hydrocarbons emanating from the lacquer coating the ballast chokes of lighting equipment, when in use, could affect the growth of plants in controlled environment rooms (Wills & Patterson, 1970).
Perception of Ethylene by Plants – Ethylene Receptors
Authors: Binder Brad M. , Chang Caren , Schaller G. Eric
Published: May 2017

The first step in the perception of ethylene occurs when ethylene binds to its receptors. Over the past few decades, since the cloning of the first ethylene receptor ETR1 fromArabidopsisin 1993, a large number of studies have steadily improved our understanding about how the receptors function in the ethylene‐signalling pathway. After providing a historical overview of ethylene receptor research, what is known about several aspects of the receptors is summarized including our understanding about the evolution of the receptors from cyanobacteria into plants. Much of our knowledge about ethylene receptors comes from mutational and biochemical studies. These studies have led to a model where a copper co‐factor is delivered to the receptors by the RAN1 copper transporter. This model predicts that when ethylene binds to this copper ion in the receptor, the receptor passes through a transition state to a non‐signalling conformation. The exact nature of the output from the receptors is unknown, but current models predict that ethylene binding to the receptors deactivates the kinase activity of CONSTITUTIVE TRIPLE RESPONSE 1 (CTR1). It is now clear from published studies in several species that the receptors are not entirely overlapping in function. Several new papers are highlighted showing that the control of a particular phenotype can be under the control of a subset of receptor isoforms or even just a single receptor isoform. These differing roles are, in part, likely to be caused by differential regulation of each receptor isoform. Recent research has uncovered a number of post‐translational mechanisms that can regulate the receptors including receptor clustering, differential proteolysis of specific receptor isoforms, and regulatory proteins that specifically regulate certain receptor isoforms. Finally, models for receptor function and ethylene signal transduction are provided to explain the ability of plants to respond to a wide concentration range of ethylene as well as to re‐sensitize and recover after ethylene levels drop.