Magnon interactions in a moderately correlated Mott insulator.

Quantum fluctuations in low-dimensional systems and near quantum phase transitions have significant influences on material properties. Yet, it is difficult to experimentally gauge the strength and importance of quantum fluctuations. Here we provide a resonant inelastic x-ray scattering study of magnon excitations in Mott insulating cuprates. From the thin film of SrCuO2, single- and bi-magnon dispersions are derived. Using an effective Heisenberg Hamiltonian generated from the Hubbard model, we show that the single-magnon dispersion is only described satisfactorily when including significant quantum corrections stemming from magnon-magnon interactions. Comparative results on La2CuO4 indicate that quantum fluctuations are much stronger in SrCuO2 suggesting closer proximity to a magnetic quantum critical point. Monte Carlo calculations reveal that other magnetic orders may compete with the antiferromagnetic Néel order as the ground state. Our results indicate that SrCuO2-due to strong quantum fluctuations-is a unique starting point for the exploration of novel magnetic ground states.

Implementation of high-resolution spectroscopy for ion (and electron) temperature measurements of the divertor plasma in the Tokamak à configuration variable.

High resolution spectroscopy on the Tokamak à Configuration Variable (TCV) divertor plasma provided Doppler broadening measurements to infer the ion and neutral temperature of injected helium gas. This paper presents the Divertor Spectroscopy System's (DSS) access to He II ion temperature measurements over a broad range, ≈0.5-15 eV, with an uncertainty of <10% for most of the studied plasma discharges. TCV's shaping flexibility was employed to validate these measurements against Thomson scattering across the DSS lines of sight. In detachment-related experiments, Ti(He II) ≃ Te, making this diagnostic a reliable thermometer along the divertor leg plasma over the wide range of magnetic equilibria and divertor configurations achievable in TCV. A detailed description of the diagnostic hardware, data analysis, and sources of uncertainty is presented.

Charge and Spin Order Dichotomy in NdNiO_{2} Driven by the Capping Layer.

Superconductivity in infinite-layer nickelates holds exciting analogies with that of cuprates, with similar structures and 3d-electron count. Using resonant inelastic x-ray scattering, we studied electronic and magnetic excitations and charge density correlations in Nd_{1-x}Sr_{x}NiO_{2} thin films with and without an SrTiO_{3} capping layer. We observe dispersing magnons only in the capped samples, progressively dampened at higher doping. We detect an elastic resonant scattering peak in the uncapped x=0 compound at wave vector (∼⅓,0), remindful of the charge order signal in hole doped cuprates. The peak weakens at x=0.05 and disappears in the superconducting x=0.20 film. The role of the capping on the electronic reconstruction far from the interface remains to be understood.

Breast cancer resistance protein (Bcrp/Abcg2) is selectively modulated by lipopolysaccharide (LPS) in the mouse yolk sac.

Bacterial infection alters placental ABC transporters expression. These transporters provide fetal protection against circulating xenobiotics and environmental toxins present in maternal blood. We hypothesized that lipopolysaccharide (LPS-bacterial mimic) alters the yolk sac morphology and expression of key ABC transporters in a gestational-age dependent manner. Yolk sac samples from C57BL/6 mice were obtained at gestational ages (GD) 15.5 and GD18.5, 4 or 24 h after LPS exposure (150ug/kg; n = 8/group). Samples underwent morphometrical, qPCR and immunohistochemistry analysis. The volumetric proportions of the histological components of the yolk sac did not change in response to LPS. LPS increased Abcg2 expression at GD15.5, after 4 h of treatment (p < 0.05). No changes in Abca1, Abcb1a/b, Abcg1, Glut1, Snat1, Il-1ß, Ccl2 and Mif were observed. Il-6 and Cxcl1 were undetectable in the yolk sac throughout pregnancy. Abca1, breast cancer resistance protein (Bcrp, encoded by Abcg2) and P-glycoprotein (P-gp/ Abcb1a/b) were localized in the endodermal (uterine-facing) epithelium and to a lesser extent in the mesothelium (amnion-facing), whereas Abca1 was also localized to the endothelium of the yolk sac blood vessels. LPS increased the labeling area and intensity of Bcrp in the yolk sac's mesothelial cells at GD15.5 (4 h), whereas at GD18.5, the area of Bcrp labeling in the mesothelium (4 and 24 h) was decreased (p < 0.05). Bacterial infection has the potential to change yolk sac barrier function by affecting Bcrp and Abcg2 expression in a gestational-age dependent-manner. These changes may alter fetal exposure to xenobiotics and toxic substances present in the maternal circulation and in the uterine cavity.

A subpopulation of human Adark spermatogonia behaves as the reserve stem cell.

Human spermatogonial stem cells (SSCs) are an essential source to maintain spermatogenesis as an efficient process for daily sperm production with high self-renewal capacity along adulthood. However, the phenotype and the subpopulation that represent the real reserve SSC for the human testis remain unknown. Moreover, although SSC markers have been described for undifferentiated spermatogonia (Adark and Apale), the existence of a specific subtype that could be identified as the actual/true SSC has not yet been fully determined. Herein we evaluated spermatogonial morphology, kinetics, positioning regarding blood vasculature in relation to protein expression (UTF1, GFRA1, and KIT) as well as proliferative activity (MCM7) and identified a small subpopulation of Adark with nuclear rarefaction zone (AdVac) that behaves as the human reserve SSC. We show that AdVac is the smallest human spermatogonial population (10%), staying quiescent (89%) and positioned close to blood vessels throughout most of the stages of the seminiferous epithelium cycle (SEC) and divides only at stages I and II. Within this AdVac population, we found a smaller pool (2% of A undifferentiated spermatogonia) of entirely quiescent cells exhibiting a high expression of UTF1 and lacking GFRA1. This finding suggests them as the real human reserve SSC (AdVac UTF1+/GFRA1-/MCM7-). Additionally, Adark without nuclear vacuole (AdNoVac) and Apale have similar kinetic and high proliferative capacity throughout the SEC (47%), indicating that they are actively dividing undifferentiated spermatogonia. Identification of human stem cells with evident reserve SSC functionality may help further studies intending to sort SSCs to treat male diseases and infertility.

Development of a new compact gamma-ray spectrometer optimised for runaway electron measurements.

A new compact gamma-ray spectrometer was developed in order to optimise the measurement of bremsstrahlung radiation emitted from runaway electrons in the MeV range. The detector is based on a cerium doped lutetium-yttrium oxyorthosilicate (LYSO:Ce) scintillator coupled to a silicon photomultiplier and is insensitive to magnetic fields. A dedicated electronic board was developed to optimise the signal readout as well as for online control of the device. The detector combines a dynamic range up to 10 MeV with moderate energy non-linearity, counting rate capabilities in excess of 1 MHz, and an energy resolution that extrapolates to a few % in the MeV range, thus meeting the requirements for its application to runaway electron studies by bremsstrahlung measurements in the gamma-ray energy range.

Blood from the right atrium may provide closer estimates of mixed venous saturation than blood from the superior vena cava. A pilot study.

BACKGROUND: As a rule, central venous catheters (CVC) should not be positioned in the right atrium (RA) to avoid the risk of perforation and cardiac tamponade. However, in ICUs where ECG monitoring can detect any initial damage of the atrial wall, CVCs may probably be safely positioned in the RA. We investigated whether mixed venous saturation (SvO2) was better estimated by measuring central venous saturation (ScvO2) in the RA or in the superior vena cava (SVC) in patients undergoing cardiac surgery. METHODS: A CVC and a pulmonary artery catheter (PAC) were positioned before surgical coronary revascularization in sixty patients. Under transesophageal echocardiographic guidance, CVC tips were randomly positioned inside the RA (group A) or the SVC (group C). In each patient, eight pairs of blood samples were collected from CVC and PAC distal ports and saturation measured. Cardiac arrhythmias that occurred in the first 48 postoperative hours and CVC tip position on chest X-rays were also registered. RESULTS: ScvO2 and SvO2 correlated better in group A (r=0.95) than in group C (r=0.84). The 95% interval of confidence of the gap between ScvO2 and SvO2 was narrower in group A (-6.9/+ 3.2 vs. -11.6/+5.5; p<.01). The incidence of arrhythmias was equal in the two groups (16.7%). On chest X-rays, CVC tips were 5.4 (SD=3.6) cm below the tracheal carina in group A and 5.3 (SD=3.9) cm in group C. CONCLUSION: In monitored patients, positioning CVC tips in the RA rather than in the SVC may allow closer estimates of SvO2 and may be safe. Yet, safety should be confirmed by further studies with larger samples of patients.

Can stable isotope analysis reveal dietary differences among groups with distinct income levels in the city of Piracicaba (southeast region, Brazil)?

BACKGROUND: The present study aimed to determine whether the δ(13)C and δ(15)N of fingernails (δ(13)CF and δ(15)NF, respectively) would exhibit differences between groups from different income levels in the city of Piracicaba, Brazil. METHODS: In 2010, the fingernails of 273 participants belonging to six income groups were analysed to determine isotopic composition. δ(13)CF and δ(15)NF were compared with the stable isotope of a putative diet (δ(13)CD and δ(15)ND , respectively), which was estimated via an isotopic mass balance using, as a weighting factor, macronutrient intake by the main food items, as obtained by the 2008-2009 household food purchases conducted by the Brazilian Institute of Geography and Statistics. RESULTS: δ(13)CF values showed a decreasing trend towards the lower income level groups, in accordance with the δ(13)CD values that showed the same trend. This isotopic change was mainly a result of the higher consumption of beef, bread, soft drinks and dairy by the highest income group; and also as a result of the higher consumption of soybean oil, rice and sugar by the lowest income group. The δ(15)NF values failed to capture differences in groups between income levels. This outcome was not expected because individuals in a higher income group tend to consume more animal protein and, as a result of the trophic fractionation, have higher δ(15)N values. CONCLUSIONS: The combination of household purchase surveys and stable isotopic composition in modern humans is found to be a valuable tool, especially with respect to determining the role of C3 and C4 plants through the complex modern food chain.

Carbon and nitrogen stock and fluxes in coastal Atlantic Forest of southeast Brazil: potential impacts of climate change on biogeochemical functioning.

The Atlantic Forest is one of the most important biomes of Brazil. Originally covering approximately 1.5 million of km², today this area has been reduced to 12% of its original size. Climate changes may alter the structure and the functioning of this tropical forest. Here we explore how increases in temperature and changes in precipitation distribution could affect dynamics of carbon and nitrogen in coastal Atlantic Forest of the southeast region of Brazil The main conclusion of this article is that the coastal Atlantic Forest has high stocks of carbon and nitrogen above ground, and especially, below ground. An increase in temperature may transform these forests from important carbon sinks to carbon sources by increasing loss of carbon and nitrogen to the atmosphere. However, this conclusion should be viewed with caution because it is based on limited information. Therefore, more studies are urgently needed to enable us to make more accurate predictions.

Nitrogen mass balance in the Brazilian Amazon: an update.

The main purpose of this study is to perform a nitrogen budget survey for the entire Brazilian Amazon region. The main inputs of nitrogen to the region are biological nitrogen fixation occurring in tropical forests (7.7 Tg.yr(-1)), and biological nitrogen fixation in agricultural lands mainly due to the cultivation of a large area with soybean, which is an important nitrogen-fixing crop (1.68 Tg.yr(-1)). The input due to the use of N fertilizers (0.48 Tg.yr(-1)) is still incipient compared to the other two inputs mentioned above. The major output flux is the riverine flux, equal to 2.80 Tg.yr(-1) and export related to foodstuff, mainly the transport of soybean and beef to other parts of the country. The continuous population growth and high rate of urbanization may pose new threats to the nitrogen cycle of the region through the burning of fossil fuel and dumping of raw domestic sewage in rivers and streams of the region.

Humidity control can compensate for the damage induced in protein crystals by alien solutions.

The use of relative humidity control of protein crystals to overcome some of the shortcomings of soaking ligands (i.e. inhibitors, substrate analogs, weak ligands) into pre-grown apoprotein crystals has been explored. Crystals of PurE (EC 4.1.1.21), an enzyme from the purine-biosynthesis pathway of Bacillus anthracis, were used as a test case. The findings can be summarized as follows: (i) using humidity control, it is possible to improve/optimize the diffraction quality of crystals soaked in solutions of organic solvent (DMSO, ethanol) containing ligands/inhibitors; (ii) optimization of the relative humidity can compensate for the deterioration of the diffraction pattern that is observed upon desalting crystals grown in high salt; (iii) combining desalting protocols with the addition of PEG it is possible to achieve very high concentrations of weak ligands (in the 5-10 mM range) in soaking solutions and (iv) fine control of the relative humidity of crystals soaked in these solutions can compensate for the deterioration of crystal diffraction and restore `high-resolution' diffraction for structure-based and fragment-based drug design. It is suggested that these experimental protocols may be useful in other protein systems and may be applicable in academic or private research to increase the probability of obtaining structures of protein-ligand complexes at high resolution.

Incidence and severity of oral mucositis in patients undergoing haematopoietic SCT--results of a multicentre study.

Oral mucositis (OM) is a common side effect experienced during haematopoietic SCT (HSCT), and it can have a significant impact on the quality of life of patients. A descriptive nurse-led study was undertaken in 19-member centres of the Italian national transplant group (GITMO) evaluating incidence, severity and duration of OM in patients undergoing HSCT. Data from 1841 patients between 2002 and 2006 was analyzed. Initial medical history and oral cavity assessment was performed. Assessment was repeated on the day of transplant, then daily, using the WHO (World Health Organisation) oral toxicity scale. A total of 71% of the patients evaluated developed mucositis and 21.6% developed severe mucositis. Duration of OM in most cases lasted for 10-14 days and resolved along with marrow reconstitution. Oral mucostitis is a frequent side effect in patients undergoing HSCT. The onset of severe mucositis seems to be related to the conditioning regimen used. This database provides a descriptive overview of the incidence and severity of mucositis and has encouraged participating centres to adopt routine evaluation and measurement of the oral cavity. The assessment tools are still used in some centres, providing a basis for further collaborative research projects.

Dissolved nitrogen in rivers: comparing pristine and impacted regions of Brazil.

Riverine nitrogen distribution is increasingly controlled by anthropogenic activities in their watersheds, regardless of spatial scale, climate, and geographical zone. Consequently, modelling efforts to predict the export of nitrogen from rivers worldwide have used attributes such as population density, land use, urbanization and sanitation. These models have greatly enhanced our understanding of the sources and fate of nitrogen added to terrestrial systems and transported to rivers and streams, especially for developed countries of the North temperate zone. However, much of the world's population lives in developing countries of the tropics, where the effects of human activities on riverine N exports are still poorly understood. In an effort to close this gap, we compare riverine nitrogen data from 32 Brazilian rivers draining two contrasting regions in this tropical country in terms of economic development - the State of São Paulo and the Amazon. Our data include nitrogen in different dissolved forms, such as Dissolved Inorganic Nitrogen (DIN) and Dissolved Organic Nitrogen (DON). The results show that nitrogen concentrations decreased as river runoff increased in both study areas, and that concentrations were significantly higher in rivers draining the most economically developed region. The relationships between nitrogen concentrations and fluxes with demographic parameters such as population density were also determined and compared to those in temperate systems. In contrast to temperate watersheds, we found that nitrogen fluxes increased only after population densities were higher than 10 individuals per km².

Combined heart and kidney transplantation: long-term analysis of renal function and major adverse events at 20 years.

BACKGROUND: Combined heart-kidney transplantation (HKTx) is an accepted therapeutic option for patients with end-stage heart disease associated with severely impaired renal function. We report our long-term follow-up with this combined procedure. PATIENTS AND METHODS: Between April 1989 to November 2009, nine patients underwent combined simultaneous (HKTx) at our center. Seven patients were males (mean age 45.2 +/- 10.12 years); seven patients were on dialysis at the time of transplantation. RESULTS: Surgical procedures were uneventful in all patients. One patient died in the intensive care unit 41 days after transplantation. During long-term follow-up, three patients died: one due to infection and multiorgan failure 148 months after HKTx, one due to a lung neoplasm after 6 years, and one, a cerebral stroke at 34 months after transplantation. Only one patient experience renal allograft failure secondary to hypertension and cyclosporine nephrotoxicity at 10 years after HKTx with the need for renal replacement therapy. Last estimated glomerular filtration rates of all other patients was 61.3 +/- 17.4 mL/min. CONCLUSIONS: In selected patients, with coexisting end-stage cardiac and renal failure, combined HKTx with an allograft from the same donor proved to give satisfactory short- and long-term results, with a low incidence of both cardiac and renal allograft complications.

Percutaneous coronary interventions in cardiac allograft vasculopathy: a single-center experience.

OBJECTIVE: Cardiac allograft vasculopathy represents an accelerated form of obstructive coronary disease. It is the main cause of late death following heart transplantation. Percutaneous coronary intervention is considered a palliative procedure due to high restenosis rates. The aim of this study was to review our experience with percutaneous coronary interventions using stents in cardiac transplant recipients. METHODS: The present analysis included all primary adult heart transplanted patients who had been discharged from the hospital after transplantation, had a clinical follow-up of 12 months and underwent percutaneous coronary intervention (PCI). RESULTS: Seventy heart transplanted patients underwent percutaneous revascularization. Our analysis comprised 85 first-vessel procedures resulting in treatment of 135 lesions. The mean time from heart transplantation to first intervention was 9.3 +/- 4.8 years. Primary success was obtained in 96% lesions; at least 1 recurrent stenosis event occurred in 16 patients with primarily successful PCI. Lesions treated with drug-eluting stents experienced recurrent stenosis in 16% of cases. During a mean follow-up after PCI of 45.2 +/- 41.7 months, 27 deaths (19 cardiac) and 1 late re-transplantation occurred after PCI. CONCLUSION: In cardiac transplant recipients, percutaneous coronary intervention with stents can be performed safely with high rates of primary success. Restenosis rates were higher compared with coronary interventions in native coronary arteries. Drug-eluting stents seemed to favorably impact restenosis compared with bare-metal stents. The clinical benefit from percutaneous coronary intervention may be reduced due to disease progression in untreated coronary segments.

Relations between cardiovascular risk estimates and subclinical atherosclerosis in naive HIV patients: results from the HERMES study.

The aim of the study was to evaluate the cardiovascular risk factors associated with subclinical carotid atherosclerosis in antiretroviral therapy-naïve HIV-infected patients. The HERMES (HIV Exposure and Risk of Metabolic Syndrome) study enrolled therapy-naïve patients attending hospitals in the Italian coordination group for the study of allergies and HIV infection (CISAI [Coordinamento Italiano per lo Studio Allergia e Infezione da HIV]) in 2007. It was designed to identify metabolic syndrome (MS) and cardiovascular risk factors. The present analysis is a nested cross-sectional study with a subset of patients examined by carotid ultrasonography. Consecutive antiretroviral therapy-naïve HIV patients attending the facilities involved in the CISAI were included. Their 10-year probability of cardiovascular events was calculated using the Framingham Risk Score (FRS) and three other cardiovascular algorithms (the Global Framingham Risk Score - GFRS, 'Progetto Cuore' and 'SCORE'). Vascular age was estimated using a new model derived from GFRS and was compared with chronological age. The diagnosis of MS was based on the National Cholesterol Education Programme and International Diabetes Federation (IDF) definitions. Subclinical atherosclerosis was determined as ultrasound carotid intima-media thickness >0.9 mm. Out of 140 patients enrolled in the HERMES study by the four centres participating in the nested study, a total of 72 (51.4%) subjects, with no overt cardiovascular disease, were examined using carotid ultrasonography. The median age was 40 years, 79.2% men. The vascular age was 7.6 years higher than the chronological age. The factors associated with subclinical atherosclerosis were age (P < 0.0001), vascular age (P = 0.0002), body mass index (P = 0.003), waist circumference (P = 0.0002), MS (IDF definition, P = 0.004) and all the cardiovascular (CV) models (FRS, P = 0.01, GFRS, P = 0.002, Progetto Cuore, P = 0.018, SCORE, P = 0.03). Independent of other significant factors, waist circumference was significantly associated with pathological results (P = 0.007). The GFRS (area under the receiver-operating characteristic curves, 0.78; P < 0.001) had slightly better predictive accuracy than the other three CV models (FRS, areas under the curve [AUC] = 0.71, P = 0.003; Progetto Cuore, AUC = 0.74, P = 0.0005; SCORE, AUC = 0.77, P < 0.0001); 55% of patients at intermediate risk (6-20%) had subclinical carotid lesions. Subclinical carotid lesions had a highly significant direct association with all the CV risk predictors. The GFRS and vascular age were highly predictive. We recommend a carotid ultrasonographic examination at least among HIV patients with GFRS > or =6% or with an elevated waist circumference.

Trophic position of bottom-feeding fish in the Upper Paraná River floodplain.

The delta15N composition of bottom-feeding fish (iliophagous = Apareiodon affinis, Cyphocharax nagelii, Prochilodus lineatus, Steindachnerina brevipinna and S. insculpta; detritivorous = Loricariichthys platymetopon and Liposarcus anisitsi; benthophagous = Satanoperca pappaterra and Hoplosternum littorale) and their primary food sources were investigated in the upper Paraná River floodplain during rainy seasons in different environments (lotic and lentic). Two hypotheses were tested: i) that the trophic position and isotopic values of the investigated organisms (fish and food resources) vary spatially; and ii) that trophic position and isotopic compositions differ among iliophagous, detritivorous and benthophagous fish. C4 macrophytes, periphyton and phytoplankton were isotopically different in sites analyzed. Significant isotopic differences occurred in the species of each trophic category. Spatial differences were observed in the isotopic composition of P. lineatus and L. platymetopon, whose values were more enriched in the Paraná River and Pau Véio Lake. Significant spatial differences in trophic position were observed for L. platymetopon and H. littorale, which presented the highest values in the Paraná and Baía rivers, respectively. Trophic positions were significantly different among the species that composed each trophic category. These findings demonstrate that in energy-flow studies in detrital food chains generalizations concerning the grouping of fish into trophic categories and/or habitats should only be carried out after careful investigations of the local/specific trophic dynamics of the organisms.

Individual-level diet variation in four species of Brazilian frogs.

1. Many natural populations exploiting a wide range of resources are actually composed of relatively specialized individuals. 2. This interindividual variation is thought to be a consequence of the invasion of 'empty' niches in depauperate communities, generally in temperate regions. If individual niches are constrained by functional trade-offs, the expansion of the population niche is only achieved by an increase in interindividual variation, consistent with the 'niche variation hypothesis'. 3. According to this hypothesis, we should not expect interindividual variation in species belonging to highly diverse, packed communities. 4. In the present study, we measured the degree of interindividual diet variation in four species of frogs of the highly diverse Brazilian Cerrado, using both gut contents and delta(13)C stable isotopes. 5. We found evidence of significant diet variation in the four species, indicating that this phenomenon is not restricted to depauperate communities in temperate regions. 6. The lack of correlations between the frogs' morphology and diet indicate that trade-offs do not depend on the morphological characters measured here and are probably not biomechanical. The nature of the trade-offs remains unknown, but are likely to be cognitive or physiological. 7. Finally, we found a positive correlation between the population niche width and the degree of diet variation, but a null model showed that this correlation can be generated by individuals sampling randomly from a common set of resources. Therefore, albeit consistent with, our results cannot be taken as evidence in favour of the niche variation hypothesis.