Microbial characterization of a mine soil subjected to different remediation technologies combining organic and inorganic treatments and plant cultivation

RAMIRAN International ConferenceIn Portugal, additional research is needed if technologies based on the combined action of plants and the microbial communities they support within the rhizosphere are to be adopted in large-scale remediation actions (Nabais et al., 2008). Plants growing in abandoned mines are useful to indicate the mineral composition of the soil and they are able to accumulate or exclude toxic metals (Pratas et al., 2005). Taking into account that the mine degraded soils have low concentrations of plant nutrients, it is necessary to apply amendments to ensure plant cover when remediation technologies are present. But soil amendments and the development of a root system might induce shifts in the microbial community structure among the different treatments (Pérez-de-Mora et al., 2006). Moreover, data about the toxic effects of heavy metals on soil microorganisms indicated that heavy metal-sensitive bacteria are probably responsible for the decrease in bacterial activity and the competitive advantage of more tolerant ones resulted in a change in community composition (Díaz-Raviña and Bååth, 1996). Hence, relationships between the soil composition, plant species occurring above-ground and the soil microbial communities have been revealed in many research (Kourtev et al., 2003) providing an important link between above and below-ground processes in terrestrial ecosystems. Soil microbial community structure is increasingly being marketed as ecologically-relevant endpoint and it can realistically be incorporated for assessing the potential risks associated with soil amendment strategies on sustainability of soil ecosystems. Studies of different remediation technologies with mine soils in Portugal, including amendment materials from farming and industrial sources and the use of native plant species (Guiwei et al., 2008; de Varennes et al., 2009) revealed differential effects of treatments on soil enzymes and microbial respiration, suggesting a change in microbial communities. The information about this fact is scarce and had focused on soil biochemical properties, producing no clear results. Phospholipid fatty acid (PLFA) patterns are sensitive indicators of changes in microbial community structure. This technique has been used to elucidate different strategies employed by microorganism to adapt to changed environmental conditions under wide ranges of soil types, management practices, climatic origins and different perturbations (Zelles, 1999). The present study is the first attempt to characterize, by means of the analysis of PLFA patterns, soil microbial population from a Pb-contaminated mine soil subjected to different remediation technologies including revegetation with native herbaceous species

Microbial community structure in a unlimed and limed mine contaminated soil (Pb, Cu, As) with different organic and inorganic treatments

RAMIRAN International ConferenceMine contaminated soils are very unfavourable environments with limiting factors, in particular residual high levels of heavy metals, soil acidity, lack of organic matter and poor substrate structure. Toxic effects of HM on soil microorganisms have been extensively studied (Frostegård et al., 1993; Bååth et al., 1998) and the measurements of community structure indicated that the HM had an effect resulting in a change in community composition (Ellis et al., 2003; Rajapaksha et al, 2004). Nowadays molecular biology techniques, such as the analysis of phospholipid fatty acid (PLFA) patterns, make it possible to study the microbial community structure of soil microorganisms. The PLFA technique has been used to elucidate different strategies employed by microorganism to adapt to changed environmental conditions under wide ranges of soil types, management practices, climatic origins and different perturbations (Zelles, 1999). By phospholipid fatty acid analysis it is possible to examine broad scale patterns in microbial community structure (Bååth et al. 2005) and generally, after the application of multivariate statistical analyses, whole community fatty acids profiles indicate which communities are similar or different. Determination both microbial community composition and biomass size by this direct method gives results that very closely represent the in situ soil conditions and is currently used for soil monitoring purposes (Nielsen and Winding, 2002). This study aimed to evaluate the effect of different remediation technologies in a mine contaminated soil including several organic and inorganic treatments combined with liming by the soil microbial community structure analysi

Shifts in the structure of a mine contaminated soil (Pb, Cu, As) following different organic and inorganic treatments

RAMIRAN International ConferenceSoil microbial community structure is increasingly being marketed as ecologically-relevant endpoint and it can realistically be incorporated for assessing the potential risks associated with anthropogenic disturbances and soil amendment strategies on sustainability of soil ecosystems. In Portugal, additional research is needed if technologies based on the combined action of plants and the microbial communities they support within the rhizosphere are to be adopted in large-scale remediation actions (Nabais et al., 2008). The information about this fact in mine soils is scarce and had focused on soil biochemical properties, producing no clear results. Furthermore, the effects of phytoremediation as soil remediation technique and metal contamination on microbial community structural would be achieved by PLFA studies. By phospholipid fatty acid analysis it is possible to examine broad scale patterns in microbial community structure (Bååth et al. 2005) and generally, after the application of multivariate statistical analyses, whole community fatty acids profiles indicate which communities are similar or different. Determination both microbial community composition and biomass size by this direct method gives results that very closely represent the in situ soil conditions and is currently used for soil monitoring purposes (Nielsen and Winding, 2002). The present investigation studies the medium-term response in the soil microbial community structure after the application of different remediation technologies including several organic and inorganic treatments

Probing the central black hole in M87 with gamma-rays

Recent high-sensitivity observation of the nearby radio galaxy M87 have provided important insights into the central engine that drives the large-scale outflows seen in radio, optical and X-rays. This review summarizes the observational status achieved in the high energy (HE;<100 GeV) and very high energy (VHE; >100 GeV) gamma-ray domains, and discusses the theoretical progress in understanding the physical origin of this emission and its relation to the activity of the central black hole.Comment: Invited compact review to be published in Modern Physics Letters A; 19 pages, 4 figure

Myocardial Deformation Imaging Meta-Analysis in Two Cohorts of Patients from UAE and Heart Hospital Hamadmedical Corporation: A Potential Role in Assessment of Coronary Artery Disease Severity and Myocardial Viability

Introduction: The increasing prevalence of heart failure (HF) in coronary artery disease (CAD) urgently requires the establishment of new imaging techniques for early diagnosis and also to guide treatment of patients presented with acute coronary syndromes (ACS). Conventional echocardiography (CE) and electrocardiogram (ECG) are the gold standard methods in assessing myocardial ischemia (MI) and the function of the heart in patients with coronary artery disease (CAD). The lack of ST elevation by ECG and regional wall motion abnormalities by CE in non-ST segment elevation myocardial infarction (NSTEACS) in ACS patients reflect limited sensitivity of ECG and CE in identifying patients with acute coronary occlusion (ACO) and proper assessment of myocardial viability. Aim of this study: This study now evaluates the ability of strain parameters in grading the severity of CAD to detect myocardial viability in ACS through a comparative meta-analysis in two cohorts of patients living in the UAE and Qatar. The study investigates the diagnostic accuracy of left ventricular longitudinal systolic strain function (GLS) by 2D-speckle tracking echocardiography (2D-STE), Territorial Longitudinal Strain (TLS) analysis and post systolic strain (PSS) in ACS patients admitted at the emergency departments. All the patients had acute chest pain which is highly suggestive of NSTEACS along with coronary angiography (CA). Methods: The study recruited two groups, comprising of 347 patients, who were presented with acute coronary syndrome (NSTEACS) at the emergency department. The first group had 214 consecutive patients who had acute chest pain and high-risk profile and they were admitted to the emergency department at Eastern Emirates Hospitals, El-Fujairah-Dibba (EEEH), UAE. The second group consisted of 133 from emergency department at Heart Hospital- Hamad Medical Corporation (HHHMC), Qatar. In both groups, 85% of the patients were men with ages from 32 to 65 years (mean ± SD: 49.4 ± 9.5 years). Significant CAD was defined as having at least one epicardial vessel with ≥ 70% or left main>50% stenosis. All patients enrolled in this study underwent basic echocardiography, speckle tracking analysis, and coronary angiography. In 70 patients, PSS was calculated and myocardial perfusion imaging (MPI) was utilized as gold standards for the assessment of myocardial viability in patients with documented NSTEACS. The sensitivity, specificity, positive and negative predictive values of peak longitudinal systolic strain (2D-STE) and PSS were calculated. Left ventricular systolic strain was displayed as bull’s eye plot and territorial longitudinal strain (TLS) in the territory of the infarct-related artery. They were obtained within 24 hours from admission. Coronary angiography (CA) was performed within 24 hours from admission and used as a reference tests to assess the severity of CAD. Results: Echocardiogram obtained from the patients showed any no wall motion abnormalities at rest, although speckle tracking analysis was abnormal in 167 patients. In the first group of patients from the UAE, GLS showed a high sensitivity of 80% and a very high specificity of 93% for detection of significant CAD. In addition, PSS demonstrated a high sensitivity of 80% with an average specificity of 57%. The combination of GLS and PSS showed a further increase in sensitivity, specificity with positive and negative predictive values of 98%, 91%, 99% and 97%, respectively. Therefore, a very high correlation of GLS and PSS with coronary angiography was demonstrated: =0.90, p<0.0001 and R=0.88, p<0.0001, respectively. Furthermore, PSS showed a very high concordance with MPI scan (stress-rest-re injection studies) in detection of ischemic viable myocardium with very high sensitivity of 85%, r=0.79. In the Qatari (HHHMC) patients, a multi-vessel disease or left main disease (MV) was documented in 53.6%, and those with single vessel disease (SV) in 46.4%. LAD, circumflex and RCA lesions were found in 65, 50 and 39 patients, respectively. A control group of 129 cases was selected from outpatients referred to the echocardiography unit. The results showed that in comparison to CA, GLS sensitivity and specificity were 84% and 70%, respectively in all the patients. The sensitivity of GLS was 87% in MV and 80% in SV. Territorial strain sensitivity was 50%, 74% and 84.6% for the left anterior descending artery (LAD), circumflex and right coronary artery (RCA), respectively compared to specificity values of 64%, 65% and 61.7%, respectively. Conclusion: It is concluded that GLS by speckle tracking analysis is definitely an accurate method in early diagnosis of the severity of CAD in patients presenting with NSTE ACS. The combined use of GLS and PSS showed very high diagnostic accuracy for the identification of significant CAD in these patients. Strain imaging by STE may be applied to diagnose the severity of myocardial ischemia by showing reduction in peak systolic strain. Moreover, it is equally important to demonstrate post-systolic shortening which is a characteristic feature of ischemic viable myocardium after ACS requiring revascularization

Linear Accelerating Superluminal Motion Model

Accelerating superluminal motions were detected recently by multi-epoch Very Long Baseline Interferometry (VLBI) observations. Here, a Linear Accelerating Superluminal Motion (LASM) model is proposed to interpret the observed phenomena. The model provides a direct and accurate way to estimate the viewing angle of a relativistic jet. It also predicts that both Doppler boosting and deboosting effects may take place in an accelerating forward jet. The LASM model is applied to the data of the quasar 3C 273, and the initial velocity, acceleration and viewing angle of its three components are derived through model fits. The variations of the viewing angle suggest that a supermassive black hole binary system may exist in the center of 3C273. The gap between the inner and outer jet in some radio loud AGNs my be explained in terms of Doppler deboosting effects when the components accelerate to ultra-relativistic speed.Comment: 12 Pages, 3 Figues, 1 Table, Accepted for Publication by ApJ Lette

Accretion onto the Supermassive Black Hole in M87

Chandra X-ray observations of the giant elliptical galaxy M87 resolve the thermal state of the hot interstellar medium into the accretion (Bondi) radius of its central 3 10^9 Msun black hole. We measure the X-ray gas temperature and density profiles and calculate the Bondi accretion rate, Mdot_Bondi \sim 0.1 Msun/yr. The X-ray luminosity of the active nucleus of M87 observed with Chandra is L_{x, 0.5-7 \keV} \sim 7 \times 10^{40}erg/s. This value is much less than the predicted nuclear luminosity, L_{Bondi} \sim 5 \times 10^{44} erg/s, for accretion at the Bondi rate with a canonical accretion radiative efficiency of 10%. If the black hole in M87 accretes at this rate it must do so at a much lower radiative efficiency than the canonical value. The multiwavelength spectrum of the nucleus is consistent with that predicted by an advection-dominated flow. However, as is likely, the X-ray nucleus is dominated by jet emission then the properties of flow must be modified, possibly by outflows. We show that the overall energetics of the system are just consistent with the predicted Bondi nuclear power. This suggests that either most of the accretion energy is released in the relativistic jet or that the central engine of M87 undergoes on-off activity cycles. We show that, at present, the energy dumped into the ISM by the jet may reduce the accretion rate onto the black hole by a factor \propto (v_j/c_s)^{-2}, where v_j is the jet velocity and c_s the ISM sound speed, and that this is sufficient to account for the low nuclear luminosity.Comment: emulateapj.sty, revised version, accepted by Ap

Advanced Carotid Atherosclerosis and the Risk of Subsequent Major Cardiovascular Events: Carotid Ultrasound Study

Introduction: Very little is known about the role of atherosclerotic carotid plaque morphology, vulnerability, and Total Plaque Area (TPA) in the development of Major Cardiovascular Events (MCVE). Aim of this study: To assess the role of carotid atherosclerosis and the plaque morphology in the prediction of MCVE. Importance of the study: A better understanding of the role of detection of atherosclerosis and unstable plaque morphology can help to improve strategies for prevention of Acute Cardiovascular Events (ACVE) worldwide. Methods: This study analyzed the medical records of 452 patients with 2.5-years follow-up. The primary outcomes were the composite of first occurrence of stroke, cardiovascular death, and Acute Coronary Syndromes (ACS) hospitalization. Results: The results show that carotid atherosclerosis was present in 44% of patients (n=103) and this was associated with increasing conventional cardiovascular risk factors and extent of symptomatic vascular disease. During 2.5 years follow-up, 10% of patients experienced ≥ 2 MCVE. After adjustment for cardiovascular risk factors, the risk of ACS and stroke increased by 23% (95% Confidence Interval [CI]), and 45% (95% confidence interval), respectively in patients with carotid ultrasonic (US) evidence of advanced carotid atherosclerosis in comparison to control (P<0.001). The relative increase of cerebrovascular events was 22% in patients with carotid US evidence of vulnerable plaque morphology versus benign morphology. The high risk for all-cause and cardiovascular death of these patients remained significant after adjustment for various established cardiovascular risk factors in multivariable regression analysis (adjusted hazard ratio 2.4, P<0.001; compared to patients without US evidence of advanced carotid atherosclerosis features). Conclusion: It is concluded that carotid TPA and features of vulnerability were associated with an increased risk of MCVE

X-ray Spectral Survey of WGACAT Quasars, II: Optical and Radio Properties of Quasars with Low Energy X-ray Cut-offs

We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cut-offs, and that the absorbing material associated with the quasars, not intervening along the line-of-sight. The suggestion that Gigahertz Peaked Sources are associated with X-ray cut-offs remains unclear with this expanded sample.Comment: 17 pages, LaTeX, including 2 Tables and 1 figure. Ap.J. in pres

Enhancement of Late Successional Plants on Ex-Arable Land by Soil Inoculations

Restoration of species-rich grasslands on ex-arable land can help the conservation of biodiversity but faces three big challenges: absence of target plant propagules, high residual soil fertility and restoration of soil communities. Seed additions and top soil removal can solve some of these constraints, but restoring beneficial biotic soil conditions remains a challenge. Here we test the hypotheses that inoculation of soil from late secondary succession grasslands in arable receptor soil enhances performance of late successional plants, especially after top soil removal but pending on the added dose. To test this we grew mixtures of late successional plants in arable top (organic) soil or in underlying mineral soil mixed with donor soil in small or large proportions. Donor soils were collected from different grasslands that had been under restoration for 5 to 41 years, or from semi-natural grassland that has not been used intensively. Donor soil addition, especially when collected from older restoration sites, increased plant community biomass without altering its evenness. In contrast, addition of soil from semi-natural grassland promoted plant community evenness, and hence its diversity, but reduced community biomass. Effects of donor soil additions were stronger in mineral than in organic soil and larger with bigger proportions added. The variation in plant community composition was explained best by the abundances of nematodes, ergosterol concentration and soil pH. We show that in controlled conditions inoculation of soil from secondary succession grassland into ex-arable land can strongly promote target plant species, and that the role of soil biota in promoting target plant species is greatest when added after top soil removal. Together our results point out that transplantation of later secondary succession soil can promote grassland restoration on ex-arable land