227 research outputs found

    Nitric Acid Particles in Cold Thick Ice Clouds Observed at Global Scale: Link with Lightning, Temperature, and Upper Tropospheric Water Vapor

    Get PDF
    Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the Tropics (9 to 20% of clouds with T less than 202.5 K). Higher occurrences were found in the rare mid-latitudes very cold clouds. NAP occurrence increases as cloud temperature decreases and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning is the main source of the NOx, which forms NAP in cold clouds. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP play a role in the dehydration of the upper troposphere when the tropopause is colder than 195K

    Comparison of CALIPSO-Like, LaRC, and MODIS Retrievals of Ice Cloud Properties over SIRTA in France and Florida during CRYSTAL-FACE

    Get PDF
    This study compares cirrus particle effective radius retrieved by a CALIPSO-like method with two similar methods using MODIS, MODI Airborne Simulator (MAS), and GOES imagery. The CALIPSO-like method uses lidar measurements coupled with the split-window technique that uses the infrared spectral information contained at the 8.65-micrometer, 11.15-micrometer and 12.05-micrometer bands to infer the microphysical properties of cirrus clouds. The two other methods, sing passive remote sensing at visible and infrared wavelengths, are the operational MODIS cloud products (referred to by its archival product identifier MOD06 for MODIS Terra) and MODIS retrievals performed by the CERES team at LaRC (Langley Research Center) in support of CERES algorithms; the two algorithms will be referred to as MOD06- and LaRC-method, respectively. The three techniques are compared at two different latitudes: (i) the mid-latitude ice clouds study uses 18 days of observations at the Palaiseau ground-based site in France (SIRTA: Site Instrumental de Recherche par Teledetection Atmospherique) including a ground-based 532 nm lidar and the Moderate Resolution Imaging Spectrometer (MODIS) overpasses on the Terra Platform, (ii) the tropical ice clouds study uses 14 different flight legs of observations collected in Florida, during the intensive field experiment CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and cirrus Layers-Florida Area Cirrus Experiment), including the airborne Cloud Physics Lidar (CPL) and the MAS. The comparison of the three methods gives consistent results for the particle effective radius and the optical thickness, but discrepancies in cloud detection and altitudes. The study confirms the value of an active remote-sensing method (CALIPSO-like) for the study of sub-visible ice clouds, in both mid-latitudes and tropics. Nevertheless, this method is not reliable in optically very thick tropical ice clouds

    Neurofunctional correlates of attention rehabilitation in Parkinson's disease: an explorative study

    Get PDF
    The effectiveness of cognitive rehabilitation (CR) in Parkinson's disease (PD) is in its relative infancy, and nowadays there is insufficient information to support evidence-based clinical protocols. This study is aimed at testing a validated therapeutic strategy characterized by intensive computer-based attention-training program tailored to attention deficits. We further investigated the presence of synaptic plasticity by means of functional magnetic resonance imaging (fMRI). Using a randomized controlled study, we enrolled eight PD patients who underwent a CR program (Experimental group) and seven clinically/demographically-matched PD patients who underwent a placebo intervention (Control group). Brain activity was assessed using an 8-min resting state (RS) fMRI acquisition. Independent component analysis and statistical parametric mapping were used to assess the effect of CR on brain function. Significant effects were detected both at a phenotypic and at an intermediate phenotypic level. After CR, the Experimental group, in comparison with the Control group, showed a specific enhanced performance in cognitive performance as assessed by the SDMT and digit span forward. RS fMRI analysis for all networks revealed two significant groups (Experimental vs Control) × time (T0 vs T1) interaction effects on the analysis of the attention (superior parietal cortex) and central executive neural networks (dorsolateral prefrontal cortex). We demonstrated that intensive CR tailored for the impaired abilities impacts neural plasticity and improves some aspects of cognitive deficits of PD patients. The reported neurophysiological and behavioural effects corroborate the benefits of our therapeutic approach, which might have a reliable application in clinical management of cognitive defici

    Defective B-cell proliferation and maintenance of long-term memory in patients with chronic granulomatous disease

    Get PDF
    Background: Chronic granulomatous disease (CGD) is a primary immune deficiency characterized by a defect in reactive oxygen species production. Although the effect of CGD mainly reflects on the phagocytic compartment, B-cell responses are also impaired in patients with CGD. Objective: We sought to investigate how defective gp91phox expression in patients with CGD and CGD carriers might affect the B-cell compartment and maintenance of long-term memory. Methods: We studied the B-cell compartment of patients with CGD in terms of phenotype and ability to produce reactive oxygen species and proliferate on stimuli differently directed to the B-cell receptor and Toll-like receptor 9. We further studied their capacity to maintain long-term memory by measuring cellular and serologic responses to measles. Results: We show that the memory B-cell compartment is impaired among patients with CGD, as indicated by reduced total (CD191CD271) and resting (CD191CD271CD211) memory B cells in parallel to increased naive (CD191CD272IgD1) B-cell frequencies. Data on CGD carriers reveal that such alterations are related to gp91phox expression. Moreover, proliferative capabilities of B cells on selective in vitro stimulation of B-cell receptor or Toll-like receptor 9 pathways were reduced in patients with CGD compared with those seen in age-matched healthy control subjects. Significantly lower measles-specific antibody levels and antibody-secreting cell numbers were also observed, indicating a poor ability to maintain long-term memory in these patients. Conclusion: Altogether, our data suggest that patients with CGD present a defective B-cell compartment in terms of frequencies of memory B cells, response to in vitro stimulation, and maintenance of long-term antigen-specific memory

    Dual-regulated lentiviral vector for gene therapy of X-linked chronic granulomatosis

    Get PDF
    Regulated transgene expression may improve the safety and efficacy of hematopoietic stem cell (HSC) gene therapy. Clinical trials for X-linked chronic granulomatous disease (X-CGD) employing gammaretroviral vectors were limited by insertional oncogenesis or lack of persistent engraftment. Our novel strategy, based on regulated lentiviral vectors (LV), targets gp91(phox) expression to the differentiated myeloid compartment while sparing HSC, to reduce the risk of genotoxicity and potential perturbation of reactive oxygen species levels. Targeting was obtained by a myeloid-specific promoter (MSP) and posttranscriptional, microRNA-mediated regulation. We optimized both components in human bone marrow (BM) HSC and their differentiated progeny in vitro and in a xenotransplantation model, and generated therapeutic gp91(phox) expressing LVs for CGD gene therapy. All vectors restored gp91(phox) expression and function in human X-CGD myeloid cell lines, primary monocytes, and differentiated myeloid cells. While unregulated LVs ectopically expressed gp91(phox) in CD34(+) cells, transcriptionally and posttranscriptionally regulated LVs substantially reduced this off-target expression. X-CGD mice transplanted with transduced HSC restored gp91(phox) expression, and MSP-driven vectors maintained regulation during BM development. Combining transcriptional (SP146.gp91-driven) and posttranscriptional (miR-126-restricted) targeting, we achieved high levels of myeloid-specific transgene expression, entirely sparing the CD34(+) HSC compartment. This dual-targeted LV construct represents a promising candidate for further clinical development

    A phenological model for olive (Olea europaea l. var europaea) growing in italy

    Get PDF
    The calibration of a reliable phenological model for olive grown in areas characterized by great environmental heterogeneity, like Italy, where many varieties exist, is challenging and often suffers from a lack of observations, especially on budbreak. In this study, we used a database encompassing many phenological events from different olive varieties, years, and sites scattered all over Italy to identify the phases in which site-enlarged developmental rates can be well regressed against air temperature (Developmental Rate function, DR) by testing both linear and nonlinear functions. A K-fold cross-validation (KfCV) was carried out to evaluate the ability of DR functions to predict phenological development. The cross-validation showed that the phases ranging from budbreak (BBCH 01 and 07) to flowering (BBCH 61 and 65) and from the beginning of flowering (BBCH 51) to flowering can be simulated with high accuracy (r(2) = 0.93-0.96; RMSE = 3.9-6.6 days) with no appreciable difference among linear and nonlinear functions. Thus, the resulting DRs represent a simple yet reliable tool for regional phenological simulations for these phases in Italy, paving the way for a reverse modeling approach aimed at reconstructing the budbreak dates. By contrast, and despite a large number of phases explored, no appreciable results were obtained on other phases, suggesting possible interplays of different drivers that need to be further investigated

    Pectobacterium atrosepticum biosensor for monitoring blackleg and soft rot disease of potato

    Get PDF
    Pectobacterium atrosepticum (Pba) is a quarantine and threatening phytopathogen known as the causal agent of blackleg and soft rot disease of potatoes in many areas. Its early detection is then important to have healthy potato tubers and reduce economic losses. Today, conventional methods such as enzyme-linked immunosorbent-assay (ELISA) and polymerase chain reaction (PCR) are typically used for Pba detection, but they are expensive and time-consuming. Here we report on the optimization of an alternative approach based on an electrochemical impedance immunosensor combining a microfluidic module and a microelectrodes array, and having advantages in terms of low cost, ease of use and portability. For validation and for assessing its performance, the lab-on-chip platform has been compared with two standard methods (ELISA and PCR)

    SIRTA, a ground-based atmospheric observatory for cloud and aerosol research

    Get PDF
    Ground-based remote sensing observatories have a crucial role to play in providing data to improve our understanding of atmospheric processes, to test the performance of atmospheric models, and to develop new methods for future space-borne observations. Institut Pierre Simon Laplace, a French research institute in environmental sciences, created the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA), an atmospheric observatory with these goals in mind. Today SIRTA, located 20km south of Paris, operates a suite a state-of-the-art active and passive remote sensing instruments dedicated to routine monitoring of cloud and aerosol properties, and key atmospheric parameters. Detailed description of the state of the atmospheric column is progressively archived and made accessible to the scientific community. This paper describes the SIRTA infrastructure and database, and provides an overview of the scientific research associated with the observatory. Researchers using SIRTA data conduct research on atmospheric processes involving complex interactions between clouds, aerosols and radiative and dynamic processes in the atmospheric column. Atmospheric modellers working with SIRTA observations develop new methods to test their models and innovative analyses to improve parametric representations of sub-grid processes that must be accounted for in the model. SIRTA provides the means to develop data interpretation tools for future active remote sensing missions in space (e.g. CloudSat and CALIPSO). SIRTA observation and research activities take place in networks of atmospheric observatories that allow scientists to access consistent data sets from diverse regions on the globe

    Electrochemical Sensors for Liquid Biopsy and Their Integration into Lab-on-Chip Platforms: Revolutionizing the Approach to Diseases

    Get PDF
    The screening and early diagnosis of diseases are crucial for a patient’s treatment to be successful and to improve their survival rate, especially for cancer. The development of non-invasive analytical methods able to detect the biomarkers of pathologies is a critical point to define a successful treatment and a good outcome. This study extensively reviews the electrochemical methods used for the development of biosensors in a liquid biopsy, owing to their ability to provide a rapid response, precise detection, and low detection limits. We also discuss new developments in electrochemical biosensors, which can improve the specificity and sensitivity of standard analytical procedures. Electrochemical biosensors demonstrate remarkable sensitivity in detecting minute quantities of analytes, encompassing proteins, nucleic acids, and circulating tumor cells, even within challenging matrices such as urine, serum, blood, and various other body fluids. Among the various detection techniques used for the detection of cancer biomarkers, even in the picogram range, voltammetric sensors are deeply discussed in this review because of their advantages and technical characteristics. This widespread utilization stems from their ability to facilitate the quantitative detection of ions and molecules with exceptional precision. A comparison of each electrochemical technique is discussed to assist with the selection of appropriate analytical methods
    corecore