RS Ratio Research Articles

Heterogeneity in immune cell composition is associated with Mycobacterium tuberculosis replication at the granuloma level.

The control of bacterial growth is key to the prevention and treatment of tuberculosis (TB). Granulomas represent independent foci of the host immune response that present heterogeneous capacity for control of bacterial growth. At the whole tissue level, B cells and CD4 or CD8 T cells have an established role in immune protection against TB. Immune cells interact within each granuloma response, but the impact of granuloma immune composition on bacterial replication remains unknown. Here we investigate the associations between immune cell composition, including B cell, CD4, and CD8 T cells, and the state of replicating Mycobacterium tuberculosis (Mtb) within the granuloma. A measure of ribosomal RNA synthesis, the RS ratio®, represents a proxy measure of Mtb replication at the whole tissue level. We adapted the RS ratio through use of in situ hybridization, to identify replicating and non-replicating Mtb within each designated granuloma. We applied a regression model to characterize the associations between immune cell populations and the state of Mtb replication within each respective granuloma. In the evaluation of nearly 200 granulomas, we identified heterogeneity in both immune cell composition and proportion of replicating bacteria. We found clear evidence of directional associations between immune cell composition and replicating Mtb. Controlling for vaccination status and endpoint post-infection, granulomas with lower CD4 or higher CD8 cell counts are associated with a higher percent of replicating Mtb. Conversely, changes in B cell proportions were associated with little change in Mtb replication. This study establishes heterogeneity across granulomas, demonstrating that certain immune cell types are differentially associated with control of Mtb replication. These data suggest that evaluation at the granuloma level may be imperative to identifying correlates of immune protection.

Lung microenvironments harbor Mycobacterium tuberculosis phenotypes with distinct treatment responses.

Tuberculosis lung lesions are complex and harbor heterogeneous microenvironments that influence antibiotic effectiveness. Major strides have been made recently in understanding drug pharmacokinetics in pulmonary lesions, but the bacterial phenotypes that arise under these conditions and their contribution to drug tolerance are poorly understood. A pharmacodynamic marker called the RS ratio® quantifies ongoing rRNA synthesis based on the abundance of newly synthesized precursor rRNA relative to mature structural rRNA. Application of the RS ratio in the C3HeB/FeJ mouse model demonstrated that Mycobacterium tuberculosis populations residing in different tissue microenvironments are phenotypically distinct and respond differently to drug treatment with rifampin, isoniazid, or bedaquiline. This work provides a foundational basis required to address how anatomic and pathologic microenvironmental niches may contribute to long treatment duration and drug tolerance during the treatment of human tuberculosis.

Functional variability in specific root respiration translates to autotrophic differences in soil respiration in a temperate deciduous forest

CO2 release from forest soils (Rs) is a prominent flux in the global carbon cycle. Rs is derived from roots (autotrophic respiration, Ra) and microbial (heterotrophic) respiration and is highly dynamic, as it depends on edaphic and environmental conditions as well as root functional traits and microbial community composition. It is unclear how root functional traits affect root and microbial respiration rates; however, their consideration may help parse out the relative contributions of root and microbial respiration to Rs. At a temperate forest site, root systems of 3–4 functional root orders and their surrounding surface soil were carefully excavated and placed into custom trays designed to repeatedly measure Rs in situ on eight temperate tree species that varied in their root functional strategies and mycorrhizal affinity. Rs was measured bi-weekly to monthly for nearly one year using a custom chamber attached to a gas exchange system. Rs varied over time, ranging from 0.3 to 12 µmol m−2 s−1. Comparable root systems of the same species were excised from the soil and specific root respiration rates (Rr) were measured. Rr ranged from 2.5 to 9.0 nmol g−1 s−1 and was negatively correlated with root tissue density and positively related to root tissue nitrogen concentration. Using Rr to estimate Ra, we estimate that Ra accounts for <10%, on average 2–3%, of Rs for individual root systems (averaging 1.2 g dry biomass) housed in surrounding soil (average 1.3 kg dry mass) in situ; thus, Ra was roughly 20 times greater than Rh per unit mass. The contribution of Ra peaked in the fall and coincided with leaf senescence of the forest canopy. A soil-sterilizing experimental treatment designed to help isolate Ra in situ reduced bacterial biomass and shifted fungal community composition, but there was no reduction in Rs of the in-situ root-soil tray systems. The relative Ra to Rs ratio increased with root functional strategies characterized by greater specific root length and tip abundance, but also to greater root tissue density. The ratio of Ra to Rs also increased with warmer soil temperatures and decreased slightly with increasing soil moisture. We discuss how incorporating root functional traits as modulators of the autotrophic contribution to Rs could be considered when modeling total soil CO2 efflux from forests.

Genome-wide analysis of R2R3-MYB genes in cultivated peanut (Arachis hypogaea L.): Gene duplications, functional conservation, and diversification.

The cultivated Peanut (Arachis hypogaea L.), an important oilseed and edible legume, are widely grown worldwide. The R2R3-MYB transcription factor, one of the largest gene families in plants, is involved in various plant developmental processes and responds to multiple stresses. In this study we identified 196 typical R2R3-MYB genes in the genome of cultivated peanut. Comparative phylogenetic analysis with Arabidopsis divided them into 48 subgroups. The motif composition and gene structure independently supported the subgroup delineation. Collinearity analysis indicated polyploidization, tandem, and segmental duplication were the main driver of the R2R3-MYB gene amplification in peanut. Homologous gene pairs between the two subgroups showed tissue specific biased expression. In addition, a total of 90 R2R3-MYB genes showed significant differential expression levels in response to waterlogging stress. Furthermore, we identified an SNP located in the third exon region of AdMYB03-18 (AhMYB033) by association analysis, and the three haplotypes of the SNP were significantly correlated with total branch number (TBN), pod length (PL) and root-shoot ratio (RS ratio), respectively, revealing the potential function of AdMYB03-18 (AhMYB033) in improving peanut yield. Together, these studies provide evidence for functional diversity in the R2R3-MYB genes and will contribute to understanding the function of R2R3-MYB genes in peanut.

Cardiovascular autonomic reflex tests using a handheld device in the diagnosis of cardiovascular autonomic neuropathy in patients with schizophrenia

Study objectiveThis study investigated whether schizophrenia and the duration of schizophrenia were associated with cardiovascular autonomic neuropathy (CAN) by using heart rate variability (HRV) as a marker. DesignCross-sectional study. SettingThe examinations were conducted at the Centre for Psychosis Research and at the Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark. Participants240 patients with first-episode and chronic schizophrenia and 180 controls. InterventionsCAN was assessed by the cardiovascular reflex tests (CARTs): HR, RS ratio, E:I ratio, and VM using a handheld device. Main outcome measuresOne abnormal CART was interpreted as borderline CAN and ≥2 abnormal CARTs established definitive CAN. Borderline CAN and definitive CAN together was categorized as overall CAN. Analyses were adjusted for age, sex, smoking, overweight, and hypercholesterolemia. ResultsA total of 240 patients with schizophrenia (median age 42.5 [28.8, 52.3], 42.9 % women) and 180 controls (median age 45.8 [24.0, 60.1], 47.8 % women) were included, with 50.8 % of patients with schizophrenia having overall CAN compared to 27.2 % among controls. Dividing patients into patients with first-episode and chronic schizophrenia, 32.9 % vs 10 % (p < 0.001) and 59.1 % vs 41 % (p < 0.001) had overall CAN compared with controls, respectively. Schizophrenia was significantly associated with overall CAN (OR, 2.80; 95%CI, 1.75–4.50), with an OR of 2.31 (95%CI, 1.14–4.68) for first-episode schizophrenia and an OR of 2.97 (95%CI, 1.81–4.87) for chronic schizophrenia. ConclusionIt was demonstrated that a diagnosis of schizophrenia was associated with CAN. Patients with chronic schizophrenia had a significantly higher prevalence of CAN compared to patients with first-episode schizophrenia, suggesting an association between the duration of schizophrenia and CAN.

Standardized RS Ratio Metrics To Assess Tuberculosis Antimicrobial Efficacy and Potency.

The sigmoid Emax model was used to describe the rRNA synthesis ratio (RS ratio) response of Mycobacterium tuberculosis to antimicrobial concentration. RS-Emax measures the maximal ability of a drug to inhibit the RS ratio and can be used to rank-order drugs based on their RS ratio effect. RS-EC90 is the concentration needed to achieve 90% of the RS-Emax, which may guide dose selection to achieve a maximal RS ratio effect in vivo.

Divergent Trajectory of Soil Autotrophic and Heterotrophic Respiration upon Permafrost Thaw.

Warming-induced permafrost thaw may stimulate soil respiration (Rs) and thus cause a positive feedback to climate warming. However, due to the limited in situ observations, it remains unclear about how Rs and its autotrophic (Ra) and heterotrophic (Rh) components change upon permafrost thaw. Here we monitored variations in Rs and its components along a permafrost thaw sequence on the Tibetan Plateau, and explored the potential linkage of Rs components (i.e., Ra and Rh) with biotic (e.g., plant functional traits and soil microbial diversity) and abiotic factors (e.g., substrate quality). We found that Ra and Rh exhibited divergent responses to permafrost collapse: Ra increased with the time of thawing, while Rh exhibited a hump-shaped pattern along the thaw sequence. We also observed different drivers of thaw-induced changes in the ratios of Ra:Rs and Rh:Rs. Except for soil water status, plant community structure, diversity, and root properties explained the variation in Ra:Rs ratio, soil substrate quality and microbial diversity were key factors associated with the dynamics of Rh:Rs ratio. Overall, these findings demonstrate divergent patterns and drivers of Rs components as permafrost thaw prolongs, which call for considerations in Earth system models for better forecasting permafrost carbon-climate feedback.

Soil Respiration in Planted and Naturally Regenerated Castanopis carelesii Forests during Three Years Post-Establishment

Reforestation through assisted natural regeneration usually accumulates more biomass carbon than through tree planting, but its effects on soil respiration (Rs) and its components, autotrophic respiration (Ra) and heterotrophic respiration (Rh), are poorly understood despite the importance in forest carbon cycling. In this study, we clear-cut part of a 35-year-old secondary Castanopsis carelesii (C. carelesii) forest and reforested the logged land with C. carelesii via two approaches—active tree planting and assisted natural regeneration—and measured Rs, Ra, and Rh as well as soil temperature and moisture in these forests. In the first two years following reforestation, Rs, Ra and Rh rates were mostly reduced in the two young forests compared to the secondary forest, likely due to reduced photosynthate production and thus carbon substrate input associated with the clear-cut. However, the Rh:Rs ratio was significantly greater in the young plantation than in the other two forests in the first two years, suggesting a greater loss of soil organic carbon from the young plantation. In the third year, the mean Rs, Rh, and Ra rates of the young forest established via assisted natural regeneration were similar to those of the secondary forest, but significantly greater than those of the young plantation. The rates of Rs, Rh, and Ra mostly increased exponentially with increasing soil temperature in all forests, but mostly lack significant relationships with soil moisture. These findings indicate that, compared with reforestation via tree plantation, assisted natural regeneration not only reduced the loss of soil organic carbon via soil respiration, but also had a more rapid recovery of soil respiration to the level of the secondary forest. Our study highlights that, in addition to temperature, carbon substrate availability is also important in regulating soil respiration following reforestation.

Combination of Mycobacterium tuberculosis RS Ratio and CFU Improves the Ability of Murine Efficacy Experiments to Distinguish between Drug Treatments.

ABSTRACTMurine tuberculosis drug efficacy studies have historically monitored bacterial burden based on CFU of Mycobacterium tuberculosis in lung homogenate. In an alternative approach, a recently described molecular pharmacodynamic marker called the RS ratio quantifies drug effect on a fundamental cellular process, ongoing rRNA synthesis. Here, we evaluated the ability of different pharmacodynamic markers to distinguish between treatments in three BALB/c mouse experiments at two institutions. We confirmed that different pharmacodynamic markers measure distinct biological responses. We found that a combination of pharmacodynamic markers distinguishes between treatments better than any single marker. The combination of the RS ratio with CFU showed the greatest ability to recapitulate the rank order of regimen treatment-shortening activity, providing proof of concept that simultaneous assessment of pharmacodynamic markers measuring different properties will enhance insight gained from animal models and accelerate development of new combination regimens. These results suggest potential for a new era in which antimicrobial therapies are evaluated not only on culture-based measures of bacterial burden but also on molecular assays that indicate how drugs impact the physiological state of the pathogen.

Left ventricular strain-curve morphology to distinguish between constrictive pericarditis and restrictive cardiomyopathy.

AimsTo distinguish between constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM) using cardiac magnetic resonance feature tracking (CMR‐FT) left ventricle (LV) diastolic time–strain curve patterns and myocardial strain.Methods and ResultsA total of 32 CP patients, 27 RCM patients, and 25 control subjects were examined by CMR‐FT and analysed for global strain, segmental strain, and LV time–strain curve patterns in the longitudinal, circumferential, and radial directions. Speckle tracking echocardiography (STE) strain imaging was performed in some cases. The peak global longitudinal strain (GLS) and global circumferential strain (GCS) of the RCM group were lower than those of the CP group. GLS [median (interquartile range) CP vs. RCM: −11.15 (−12.85, −9.35) vs. −6.5 (−8.75, −4.85), P < 0.001] and GCS (CP vs. RCM: −16.89 ± 5.11 vs. −13.37 ± 5.79, P < 0.001). In circumferential and radial directions, the strain ratios of the LV lateral/septal wall (LW/SW) of the CP group were significantly lower than those of the RCM group at the basal and mid segments. The CS ratio of LW/SW at the basal segment [CP vs. RCM: 0.95 (0.85, 1.25) vs. 1.43 (1.18, 1.89), P < 0.001] and mid segment [CP vs. RCM: 1.05 (0.92, 1.15) vs. 1.18 (1.06, 1.49), P = 0.026]. The RS ratio of LW/SW at the basal segment [CP vs. RCM: 0.97 (0.76, 1.37) vs. 1.55 (1.08, 2.31), P = 0.006] and mid segment [CP vs. RCM: 0.95 (0.70, 1.28) vs. 1.79 (1.32, 2.92), P < 0.001]. In the longitudinal and circumferential directions, the characteristic ‘plateau’ pattern of time–strain curves could be seen in the CP but not in the RCM during the diastole. The GCS ratio of 0–50%/50–75% diastolic period of the CP was higher than that of the RCM [CP vs. RCM: 17.01 (8.67, 23.75) vs. 5.38 (1.93, 11.24), P = 0.001], while the GCS ratio of 50–75%/75–100% diastolic period was lower than that of the RCM [CP vs. RCM: 0.36 (0.15, 1.67) vs. 1.12 (0.70, 5.58), P < 0.001]. The peak GLS (sensitivity, 85%; specificity, 78%) and the GCS ratio of 0–50%/50–75% diastolic period (sensitivity, 88%; specificity, 73%) had higher differential diagnosis value.ConclusionsThe CMR‐FT could distinctly differentiate CP from RCM based on LV myocardial strain and LV time–strain curve patterns. The characteristic ‘plateau’ pattern of the time–strain curve is specific for CP and not RCM and this curve can also be duplicated by STE.

Litter decomposition of six tree species on indigenous agroforestry farms in south-eastern Ethiopia in relation to litterfall carbon inputs and modelled soil respiration

The indigenous agroforestry systems practised by smallholders in south-eastern Ethiopia have high biodiversity and productivity. However, little is known about their carbon (C) inputs and outputs. We carried out a 1-year litterbag study to determine leaf litter decomposition k constants for six woody species common to these agroforestry systems. The k values were then used to calculate the decomposition C losses from measured litterfall C fluxes and the results compared to modelled soil respiration (Rs) C losses. Litterbag weight loss at the end of the year was 100% or nearly so, k values 2.582–6.108 (yr−1) and half-life 41–112 days. k values were significantly (p = 0.023) correlated with litter N contents, nearly so with C/N ratios (p = 0.053), but not with other nutrients (Ca, Mg and K), and negatively correlated with temperature (p = 0.080). Using species, farm elevation, temperature and litter quality as predictors, partial least squares regression explained 48% of the variation in k. Depending on species, estimated decomposition C losses from litterfall were 18 to 58% lower than annual litterfall C inputs. Using a heterotrophic respiration (Rh) to Rs ratio of 0.5, modelled Rh C losses were 89 to 238% of litterfall decomposition C losses estimated using k values. However, using an Rh/Rs ratio of 0.27, which is appropriate for tropical humid forests, Rh C losses were 11 to 138% of estimated litterfall decomposition C losses. Our decomposition and soil respiration estimates indicate that litterfall is sufficient to maintain soil organic C contents and thereby the soil fertility of these unique agroforestry systems.

Development of a pro-arrhythmic ex vivo intact human and porcine model: cardiac electrophysiological changes associated with cellular uncoupling

We describe a human and large animal Langendorff experimental apparatus for live electrophysiological studies and measure the electrophysiological changes due to gap junction uncoupling in human and porcine hearts. The resultant ex vivo intact human and porcine model can bridge the translational gap between smaller simple laboratory models and clinical research. In particular, electrophysiological models would benefit from the greater myocardial mass of a large heart due to its effects on far-field signal, electrode contact issues and motion artefacts, consequently more closely mimicking the clinical setting. Porcine (n = 9) and human (n = 4) donor hearts were perfused on a custom-designed Langendorff apparatus. Epicardial electrograms were collected at 16 sites across the left atrium and left ventricle. A total of 1 mM of carbenoxolone was administered at 5 ml/min to induce cellular uncoupling, and then recordings were repeated at the same sites. Changes in electrogram characteristics were analysed. We demonstrate the viability of a controlled ex vivo model of intact porcine and human hearts for electrophysiology with pharmacological modulation. Carbenoxolone reduces cellular coupling and changes contact electrogram features. The time from stimulus artefact to (-dV/dt)max increased between baseline and carbenoxolone (47.9 ± 4.1–67.2 ± 2.7 ms) indicating conduction slowing. The features with the largest percentage change between baseline and carbenoxolone were fractionation + 185.3%, endpoint amplitude − 106.9%, S-endpoint gradient + 54.9%, S point − 39.4%, RS ratio + 38.6% and (-dV/dt)max − 20.9%. The physiological relevance of this methodological tool is that it provides a model to further investigate pharmacologically induced pro-arrhythmic substrates.

Assessment of the Modified CHA2DS2VASc Risk Score in Predicting Mortality in Patients Hospitalized With COVID-19

Since the modified CHA2DS2VASC (M-CHA2DS2VASc) risk score includes the prognostic risk factors for COVID-19; we assumed that it might predict in-hospital mortality and identify high-risk patients at an earlier stage compared with troponin increase and neutrophil-lymphocyte ratio (NLR). We aimed to investigate whether M-CHA2DS2VASC RS is an independent predictor of mortality in patients hospitalized with COVID-19 and to compare its discriminative ability with troponin increase and NLR in terms of predicting mortality. A total of 694 patients were retrospectively analyzed and divided into 3 groups according to M-CHA2DS2VASC RS which was simply created by changing gender criteria of the CHA2DS2VASC RS from female to male (Group 1, score 0-1 (n = 289); group 2, score 2-3 (n = 231) and group 3, score ≥4 (n = 174)). Adverse clinical events were defined as in-hospital mortality, admission to intensive care unit, need for high-flow oxygen and/or intubation. As the M-CHA2DS2VASC RS increased, adverse clinical outcomes were also significantly increased (Group 1, 3.8%; group 2, 12.6%; group 3, 20.8%; p <0.001 for in-hospital mortality). The multivariate logistic regression analysis showed that M-CHA2DS2VASC RS, troponin increase and neutrophil-lymphocyte ratio were independent predictors of in-hospital mortality (p = 0.005, odds ratio 1.29 per scale for M-CHA2DS2VASC RS). In receiver operating characteristic analysis, comparative discriminative ability of M-CHA2DS2VASC RS was superior to CHA2DS2VASC RS score. Area under the curve (AUC) values for in-hospital mortality was 0.70 and 0.64, respectively. (AUCM-CHA2DS2-VASc vs. AUCCHA2DS2-VASc z test = 3.56, p 0.0004) In conclusion, admission M-CHA2DS2VASc RS may be a useful tool to predict in-hospital mortality in patients with COVID-19.

Soil respiration and net ecosystem productivity in a chronosequence of hybrid poplar plantations

Forest stand age can affect ecosystem carbon (C) cycling and net ecosystem productivity (NEP). In Canada, establishment of short-rotation plantations on previously agricultural lands has been ongoing, but the effect of stand development on soil respiration (Rs) and NEP in such plantations is poorly understood. These types of data are essential for constraining ecosystem models that simulate C dynamics over the rotation of a plantation. We studied Rs (including autotrophic, Ra, and heterotrophic, Rh) and NEP in 2008 and 2009 in a chronosequence of 5-, 8-, 14-, and 16-yr-old (ages in 2009) hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker) plantations in northern Alberta. The highest Rs and NEP were generally found in the 14-yr-old stand. Seasonal variations in Rs were similar among the plantations, with most of the variation explained by soil temperature at the 10 cm depth in 2008 with far less explained in 2009, a much drier year. In diurnal measurements, hysteresis was found between soil respiration and soil temperature, with the patterns of hysteresis different among stand ages. Soil respiration in the 14-yr-old plantation had the greatest sensitivity to temperature changes. Stand age did not affect the Rh:Rs ratio, whereas the NEP exhibited strong inter-annual variability. We conclude that stand age was a major factor affecting Rs and NEP, and such effects should be considered in empirical models used to simulate ecosystem C dynamics to evaluate potentials for C sequestration and the C source–sink relationship in short-rotation woody crop systems.

Dynamic-Ventilatory Digital Radiography in Air Flow Limitation: A Change in Lung Area Reflects Air Trapping

Objective: The aim of this study was to determine the utility of dynamic-ventilatory digital radiography (DR) for pulmonary function assessment in patients with airflow limitation. Methods: One hundred and eighteen patients with airflow limitation (72 patients with lung cancer before surgery, 35 patients with chronic obstructive pulmonary disease [COPD], 6 patients with asthma, and 5 patients with asthma-COPD overlap syndrome) were assessed with dynamic-ventilatory DR. The patients were instructed to inhale and exhale slowly and maximally. Sequential chest X-ray images were captured in 15 frames per second using a dynamic flat-panel imaging system. The relationship between the lung area and the rate of change in the lung area due to respiratory motion with respect to pulmonary function was analyzed. Results: The rate of change in the lung area from maximum inspiration to maximum expiration (Rs ratio) was associated with the RV/TLC ratio (r = 0.48, p < 0.01) and the percentage of the predicted FEV₁ (r = –0.33, p < 0.01) in patients with airflow limitations. The Rs ratio also decreased in an FEV₁-dependent manner. Conclusion: The rate of change in the lung area due to respiratory motion evaluated with dynamic DR reflects air trapping. Dynamic DR is a potential tool for the comprehensive assessment of pulmonary function in patients with COPD.

Formulation of sustained release bioadhesive minitablets containing solid dispersion of levofloxacin for once daily ocular use

This study aimed to increase ocular residence time of levofloxacin by formulation into zero-order sustained release mucoadhesive minitablets for once daily administration using a hydrophobic–hydrophilic polymeric matrix. Levofloxacin was first formulated into solid dispersion with different ratios of Eudragit® RS then the resulting solid dispersion was mixed with different concentrations of Carbopol® and other excipients to be finally compressed into minitablets. A 24 full factorial design was employed to estimate the effects and interactions of two formulation factors, and to establish their relationships with selected responses in the developed minitablets. The studied factors were: drug to Eudragit® RS ratio, and percent of Carbopol® in the minitablets. Sixteen ocular minitablets formulations were prepared and evaluated for the cumulative percentages drug release at 6, 12, and 24 h, as well as mucoadhesion time, mucoadhesive strength, and swelling index as response variables. After optimizing the responses, the optimized formulation was found to be stable on sterilization using gamma-irradiation and storage at 40 °C/75% RH for six months. In vivo testing of the optimized formulation showed that the minitablets extended levofloxacin release up to 24 h without causing any ocular irritation. The optimized formulation exhibited superior microbiological activity compared to the commercial product.

Globally rising soil heterotrophic respiration over recent decades.

Global soils store at least twice as much carbon as Earth's atmosphere1,2. The global soil-to-atmosphere (or total soil respiration, RS) carbon dioxide (CO2) flux is increasing3,4, but the degree to which climate change will stimulate carbon losses from soils as a result of heterotrophic respiration (RH) remains highly uncertain5-8. Here we use an updated global soil respiration database9 to show that the observed soil surface RH:RS ratio increased significantly, from 0.54 to 0.63, between 1990 and 2014 (P = 0.009). Three additional lines of evidence provide support for this finding. By analysing two separate global gross primary production datasets10,11, we find that the ratios of both RH and RS to gross primary production have increased over time. Similarly, significant increases in RH are observed against the longest available solar-induced chlorophyll fluorescence global dataset, as well as gross primary production computed by an ensemble of global land models. We also show that the ratio of night-time net ecosystem exchange to gross primary production is rising across the FLUXNET201512 dataset. All trends are robust to sampling variability in ecosystem type, disturbance, methodology, CO2 fertilization effects and mean climate. Taken together, our findings provide observational evidence that global RH is rising, probably in response to environmental changes, consistent with meta-analyses13-16 and long-term experiments17. This suggests that climate-driven losses of soil carbon are currently occurring across many ecosystems, with a detectable and sustained trend emerging at the global scale.

The resistive switching effects in BaTiO3/ZnO/BaTiO3/Carbon film

An obvious unipolar resistance switching is observed in BaTiO3/ZnO/BaTiO3/Carbon films. The resistance switching effect and the set voltage can be modulated by light irradiation. The RS ratio increases with light intensity. These phenomena are explained using trap/detrap mechanism.

The use of infrared thermal imaging as a non-destructive screening tool for identifying drought-tolerant lentil genotypes

Lentil (Lens culinaris, Medik.) is an important legume crop, which often experience drought stress especially at the flowering and grain filling phenological stages. The availability of efficient and robust screening tools based on relevant non-destructive quantifiable traits would facilitate research on crop improvement for drought tolerance. The objective of this study was to evaluate the drought tolerance of 37 lentil genotypes using infrared thermal imaging (IRTI), drought tolerance parameters and multivariate data analysis. Potted plants were kept in a completely randomized design in a growth chamber with five replicates. Plants were subjected to three different drought treatments: 100, 50 and 20% of field capacity at the onset of reproductive period. The relative drought stress tolerance was determined based on a set of morpho-physiological parameters including non-destructive measures based on IRTI, such as: canopy temperature (Tc), canopy temperature depression (CTD) and crop water stress index (CWSI) during the growing period and destructive measures at harvest, such as: dry root-shoot ratio (RS ratio), relative water content (RWC) and harvest index (HI). The drought tolerance indices used were drought susceptibility index (DSI) and drought tolerance efficiency (DTE). Results showed that drought stress treatments significantly reduced the RWC, HI, CTD and DSI, whereas, the values of Tc, CWSI, RS ratio and DTE significantly increased for all the genotypes. The cluster analysis from morpho-physiological parameters clustered genotypes in three distinctive groups as per the level of drought stress tolerance. The genotypes with higher values of RS ratio, RWC, HI, DTE and CTD and lower values of DSI, Tc and CWSI were identified as drought-tolerant genotypes. Based on this preliminary screening, the genotypes Digger, Cumra, Indianhead, ILL 5588, ILL 6002 and ILL 5582 were identified as promising drought-tolerant genotypes. It can be concluded that the IRTI analysis is a high-throughput constructive screening tool along with RS ratio, RWC, HI and other drought tolerance indices to define the drought stress tolerance variability within lentil plants. These results provide a foundation for future research directed at identifying powerful drought assessment traits using rapid and non-destructive techniques, such as IRTI along with the yield traits, and understanding the biochemical and molecular mechanisms underlying lentil tolerance to drought stress.

Unipolar atrial electrogram morphology from an epicardial and endocardial perspective

Endo-epicardial asynchrony (EEA) and the interplay between the endocardial and epicardial layers could be important in the pathophysiology of atrial arrhythmias. The morphologic differences between epicardial and endocardial atrial electrograms have not yet been described, and electrogram morphology may hold information about the presence of EEA. The purpose of this study was to directly compare epicardial to endocardial unipolar electrogram morphology during sinus rhythm (SR) and to evaluate whether EEA contributes to electrogram fractionation by correlating fractionation to spatial activation patterns. In 26 patients undergoing cardiac surgery, unipolar electrograms were simultaneously recorded from the epicardium and endocardium at the inferior, middle, and superior right atrial (RA) free wall during SR. Potentials were analyzed for epi-endocardial differences in local activation time, voltage, RS ratio, and fractionation. The surrounding and opposite electrograms of fractionated deflections were evaluated for corresponding local activation times in order to determine whether fractionation originated from EEA. The superior RA was predisposed to delayed activation, EEA, and fractionation. Both epicardial and endocardial electrograms demonstrated an S-predominance. Fractionation was mostly similar between the 2 sides; however, incidentally deflections up to 4 mV on 1 side could be absent on the other side. Remote activation was responsible for most fractionated deflections (95%) in SR, of which 4% could be attributed to EEA. Local epi-endocardial differences in electrogram fractionation occur occasionally during SR but will likely increase during arrhythmias due to increasing EEA and (functional) conduction disorders. Electrogram fractionation can originate from EEA, and this study demonstrated that unipolar electrogram fractionation can potentially identify EEA.