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1.
Rev Sci Instrum ; 95(3)2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38436450

ABSTRACT

Magnetized Liner Inertial Fusion experiments have been performed at the Z facility at Sandia National Laboratories. These experiments use deuterium fuel, which produces 2.45 MeV neutrons on reaching thermonuclear conditions. To study the spatial structure of neutron production, the one-dimensional imager of neutrons diagnostic was fielded to record axial resolved neutron images. In this diagnostic, neutrons passing through a rolled edge aperture form an image on a CR-39-based solid state nuclear track detector. Here, we present a modified generalized expectation-maximization algorithm to reconstruct an axial neutron emission profile of the stagnated fusion plasma. We validate the approach by comparing the reconstructed neutron emission profile to an x-ray emission profile provided by a time-integrated pinhole camera.

2.
Rev Med Interne ; 43(12): 696-702, 2022 Dec.
Article in French | MEDLINE | ID: mdl-36372632

ABSTRACT

INTRODUCTION: Infections are responsible for a part of the overall mortality in primary Sjögren's syndrome patients (pSS). Our retrospective monocentric study aimed at describing infections reported in a population of pSS hospitalized patients, along with the characteristics of their disease. METHODS: Patients with SS have been randomly selected from our hospital database claim, between 2009 and 2018. After careful analysis of their medical chart, only patients with pSS and fulfilling ACR/EULAR 2016 diagnosis criteria were included. We collected main clinical, biological and pathological characteristics of SS, along with all the reported infections during the follow-up. The characteristics of the disease were compared according to the presence of an infection in hospitalization. RESULTS: In total, 109 pSS patients were included (93% of women, mean age 53.6±14.3 years, mean follow-up 8.2±8.4 years). Fifty-one percent had been exposed to hydroxychloroquine (HCQ). Seventy-eight infections were recorded in 47 (43%) patients. Twenty-five infections were recorded in hospitalization (5 in critical care) in 20 (18%) patients, whom leading causes were urinary tract (28%), pulmonary (24%), ENT (16%), and intestinal (12%) infections. pSS patients with infections in hospitalization were older, exhibited more hypocomplementemia, and were less exposed to HCQ. We found no difference in immunosuppressive treatments exposure. CONCLUSIONS: The impact of HCQ exposure on infectious risk needs further investigations. Broad vaccination campaign and tight control of sicca syndrome could lead to a better control of infection risk.


Subject(s)
Sjogren's Syndrome , Adult , Aged , Female , Humans , Middle Aged , Hospitals , Hydroxychloroquine , Lung , Retrospective Studies , Sjogren's Syndrome/complications , Sjogren's Syndrome/epidemiology , Sjogren's Syndrome/diagnosis , Male
3.
Intensive Care Med Exp ; 9(1): 19, 2021 Apr 07.
Article in English | MEDLINE | ID: mdl-33825987

ABSTRACT

BACKGROUND: To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis. METHODS: A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 h after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the proinflammatory interleukin-1ß (IL-1ß) in diaphragms. RESULTS: CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1ß mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome c oxidase activity. CONCLUSION: In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

5.
Antimicrob Agents Chemother ; 64(12)2020 11 17.
Article in English | MEDLINE | ID: mdl-33020154

ABSTRACT

Cefuroxime (CXM) is an antibiotic recommended for surgical site infection prevention in cardiac surgery. However, the dosing regimens commonly used do not sustain therapeutic concentrations throughout surgery. The aim of this study was to conduct a population analysis of CXM pharmacokinetics (PK), and to propose an optimized dosing regimen. Adult patients undergoing cardiac surgery under cardiopulmonary bypass (CPB) received a 1,500 mg CXM intravenous bolus followed by a 750 mg bolus at CPB priming, then every 2 h thereafter. Model-based PK simulations were used to develop an optimized dosing regimen and evaluate its efficacy in attaining various concentration thresholds, including those recommended in US and European guidelines. In total, 447 CXM measurements were acquired in 50 patients. A two-compartment model best fit the data, with total body weight and creatinine clearance determining interpatient variability in the central and peripheral volumes of distribution, and in elimination clearance, respectively. Using our optimized dosing regimen, different dosing schemes adapted to body weight and renal function were calculated to attain total concentration thresholds ranging from 12 to 96 mg/liter. Our simulations showed that the dosing regimens recommended in US and European guidelines failed to maintain concentrations above 48 mg/liter. Our individualized dosing strategy was capable of ensuring therapeutic CXM concentrations conforming to each target threshold. Our model yielded an optimized CXM dosing regimen adapted to body weight and renal function, and sustaining therapeutic concentrations consistent with each desired threshold. The optimal target concentration and necessary duration of its maintenance in cardiac surgery still remain unclear.


Subject(s)
Cardiac Surgical Procedures , Cefuroxime , Adult , Anti-Bacterial Agents/therapeutic use , Antibiotic Prophylaxis , Cardiopulmonary Bypass , Humans , Surgical Wound Infection/drug therapy
7.
Anaesthesia ; 75(3): 323-330, 2020 03.
Article in English | MEDLINE | ID: mdl-31802485

ABSTRACT

We aimed to compare the reliability of aspiration via a nasogastric tube with ultrasound for assessment of residual gastric volume. Sixty-one adult patients who were mechanically ventilated and received continuous enteral feeding through a nasogastric tube for > 48 h were included. A first qualitative and quantitative ultrasound examination of the gastric antrum was followed by gastric suctioning, performed by an operator blinded to the result of the ultrasound examination. A second ultrasound examination was performed thereafter, followed by re-injection of the aspirated gastric contents (≤ 250 ml) into the stomach. A third ultrasound assessment was then immediately performed. If the suctioned volume was ≥ 250 ml, 250 mg erythromycin was infused over 30 min. A fourth ultrasound was performed 90 min after the third. Sixty (98%) patients had a qualitatively assessed full stomach at first ultrasound examination vs. 52 (85%) after gastric suctioning (p = 0.016). The calculated gastric volume significantly decreased after gastric suctioning, without a significant decrease in the number of patients with volume ≥ 250 ml. Four of the nine patients with calculated gastric volume ≥ 250 ml had vomiting within the last 24 h (p = 0.013). The antral cross-sectional area significantly decreased between the third and the fourth ultrasound examination (p = 0.015). Erythromycin infusion did not make a significant difference to gastric volume (n = 10). Our results demonstrate that gastric suctioning is not a reliable tool for monitoring residual gastric volume. Gastric ultrasound is a feasible and promising tool for gastric volume monitoring in clinical practice.


Subject(s)
Respiratory Aspiration of Gastric Contents/diagnostic imaging , Stomach/diagnostic imaging , Suction/methods , Adult , Aged , Anti-Bacterial Agents/adverse effects , Cohort Studies , Erythromycin/adverse effects , Female , Gastric Emptying , Gastrointestinal Contents , Humans , Intubation, Gastrointestinal , Male , Middle Aged , Monitoring, Intraoperative , Prospective Studies , Reproducibility of Results , Stomach/anatomy & histology , Stomach/drug effects , Ultrasonography , Vomiting/etiology
8.
Clin Radiol ; 74(8): 653.e19-653.e25, 2019 Aug.
Article in English | MEDLINE | ID: mdl-31078275

ABSTRACT

AIM: To review all cases of B3 lesion diagnosed at initial image-guided needle biopsy over two 5-year cohorts to identify upgrade rates to malignancy and the effect of changing guidance on the management of such lesions. MATERIALS AND METHODS: Data was collected retrospectively. Mammographic features, biopsy type and management were recorded for each lesion. Upgrade rates for each B3 histological category were quantified. Statistical analysis was performed using SPSS. RESULTS: There were 224 cases in 2005-2010 and 240 cases in 2010-2015. Mammographically 211 lesions were microcalcifications, 182 masses, 65 distortions and six asymmetric densities with no difference in the mammographic features in the two cohorts. Two hundred and eight 14 G core biopsies and 256 initial vacuum-assisted biopsies were performed. There was a statistically significant reduction in benign surgical biopsies and an increase in second-line vacuum biopsy/excision in the latter cohort, with no significant change in the upgrade rate. There was an overall 6% upgrade to invasive malignancy and 13% upgrade to ductal carcinoma in situ (DCIS). The upgrade rates for the following histological categories were atypical intraductal epithelial proliferation (AIDEP) 33.2% (21/63); classical (not pleomorphic) in situ lobular neoplasia (ISLN) 18.2% (6/33); flat epithelial hyperplasia (FEA) 21.7% (20/92); papilloma with atypia 53.8% (7/13), without atypia 12.1% (8/66); and radial scar/complex sclerosing lesion with atypia 16.7% (2/12), and without atypia 7.9% (6/76). CONCLUSION: Upgrade rates remain high for some histological categories even with first-line use of vacuum biopsy. Management of borderline lesions should be considered carefully in a multidisciplinary meeting. In many cases, the need for diagnostic surgical excision has been replaced by image-guided vacuum sampling.


Subject(s)
Breast Neoplasms/diagnostic imaging , Breast Neoplasms/pathology , Mammography/methods , Medical Audit/statistics & numerical data , Practice Patterns, Physicians'/statistics & numerical data , Breast/diagnostic imaging , Breast/pathology , Female , Humans , Image-Guided Biopsy , Medical Audit/methods , Retrospective Studies
9.
Clin Radiol ; 74(4): 327.e1-327.e5, 2019 04.
Article in English | MEDLINE | ID: mdl-30745157

ABSTRACT

AIM: To evaluate whether digital breast tomosynthesis (DBT) can predict if circumscribed masses are benign or malignant by assessing margin sharpness. MATERIALS AND METHODS: Circumscribed masses were evaluated on co-registered two-dimensional digital mammography (2DDM) and DBT. Lesions were categorised as follows: category 1=visible sharp border 0-25% of the total margin; category 2 = 26-50% category 3= 51-75%, and category 4=76-100%. Changes in category between 2DDM and DBT were analysed; if the category was lower on DBT the change was negative, if higher the change was positive. RESULTS: Of 759 lesions, 121 masses classified as circumscribed on DBT were included; 25 were malignant and 96 benign. Of the benign lesions, 8/96 were within category 3 or 4 on 2DDM compared with 48/96 benign lesions within category 3 or 4 on DBT (Fisher's exact test p<0.000527). Forty-eight of 51 (94.1%) lesions categorised as 3 or 4 on DBT were benign and 65/67 (97.01%) of the positive category change group were benign. Lesions in category 1 on DBT had 45.4% chance of being malignant (20/44) compared with 22.72% (20/88) on 2DDM (chi-squared test p<0.001). Sixty-five of 67 (97.01%) lesions in the positive category change group were benign and 23/54 (42.6%) lesions with either no or negative category change were malignant. CONCLUSION: The present study demonstrates 97% accuracy in predicting circumscribed lesions as benign when using positive category change and 94% accuracy when >50% of the margin is sharply defined on DBT.


Subject(s)
Breast Neoplasms/diagnostic imaging , Mammography/methods , Breast/diagnostic imaging , Diagnosis, Differential , Female , Humans , Predictive Value of Tests , Reproducibility of Results
10.
Int J Phytoremediation ; 21(3): 224-229, 2019.
Article in English | MEDLINE | ID: mdl-30656958

ABSTRACT

The aim of this work is to study and evaluate in situ, the Artemisia herba alba responses to hexavalent chromium stress in the arid and semi-arid steppe Algerian soil. This metallic pollutant was selected to its high toxicity and to its great release from several industrial and agricultural activities emissions in the area of the study region. Artemisia herba alba is a medicinal plant but also a forage species widely used in pasture. It has dominated then adapted to the arid and semi-arid climate of Algerian steppe region, due principally to their morphological and physiological characteristics. To establish this work, A. herba alba species were selected in the Algerian steppe region, and their soils were treated weekly with K2CrO4 solution for about three months. Chromium concentrations were determined in the soil and in the different plants' parts to verify its absorption and translocation with and without pollution simulation. This study demonstrated that A. herba alba has a strong resistance to high concentrations of hexavalent chromium. An increase in chromium concentrations at the different parts of plant's has been noticed, without affecting its growth and vegetative development. The results of physiological and elementary analysis indicated that chromium was absorbed by A. herba alba. Cr (VI) accumulation in plant increase when they are increasing in soil. Translocation factor results indicated that Cr (VI) was mainly accumulated by A. herba alba roots. Particle size analysis showed that the soil is poor in organic substances and mostly sandy loams with 79.77% of sand and 9.76% of clay minerals.


Subject(s)
Artemisia , Soil Pollutants , Biodegradation, Environmental , Chromium , Soil
11.
Ann Phys Rehabil Med ; 62(2): 77-83, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30273680

ABSTRACT

BACKGROUND: Flap surgery for deep pelvic pressure ulcers (PPUs) has been found effective, but the recurrence rate remains high and few risk factors have been identified. OBJECTIVE: We evaluated risk factors for PU recurrence after primary flap surgery in people with spinal cord injury (SCI). PATIENTS AND METHODS: This observational retrospective study based on medical charts included all individuals with SCI who underwent primary flap surgery for a PPU in the Hérault department in France between 2006 and 2014. Overall, 100 biomedical, psychological, socioeconomic and care management factors were studied. The primary outcome was PPU recurrence (surgical site and/or other pelvic site). The secondary outcome was recurrence at the surgical site. Cox proportional hazards regression was used to determine associated factors, estimating hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: We included 85 patients. Half had a PPU recurrence, and in one-third, the recurrence was at the surgical site. On multivariate analysis, global PPU recurrence was associated with colostomy (HR=2.79) and living with a partner (HR=2.29). Non-traumatic SCI and sacral wound were associated with PPU recurrence (HR=3.39, HR=0.48) and recurrence at the surgical site (HR=3.3, HR=0.3). CONCLUSION: Risk factors of PPU recurrence are based on both biomedical and social models. After primary flap surgery, the risk of recurrence justifies regular follow-up and strict monitoring.


Subject(s)
Postoperative Complications/etiology , Pressure Ulcer/etiology , Skin Transplantation/adverse effects , Spinal Cord Injuries/surgery , Surgical Flaps/adverse effects , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Pelvis , Postoperative Complications/pathology , Pressure Ulcer/pathology , Proportional Hazards Models , Recurrence , Regression Analysis , Retrospective Studies , Risk Factors , Spinal Cord Injuries/complications , Treatment Outcome , Young Adult
12.
J Med Vasc ; 43(6): 369-370, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30522709

ABSTRACT

Vascular leiomyosarcoma is a very rare soft tissue neoplasma. We are reporting a vascular leiomyosarcoma case arising from an unusual site: the radiocephalic vein. Despite a poor prognosis, after surgery and radiotherapy, the patient was alive without signs of recurrence two years later.


Subject(s)
Leiomyosarcoma/pathology , Upper Extremity/blood supply , Vascular Neoplasms/pathology , Veins/pathology , Aged, 80 and over , Biopsy , Female , Humans , Leiomyosarcoma/therapy , Radiotherapy, Adjuvant , Time Factors , Treatment Outcome , Vascular Neoplasms/therapy , Veins/radiation effects , Veins/surgery
13.
Osteoporos Int ; 29(11): 2389-2397, 2018 Nov.
Article in English | MEDLINE | ID: mdl-29909470

ABSTRACT

Inflammatory bowel diseases (IBDs) are associated with a decreased bone mineral density, but the impact on fractures is unknown. In our study, global risk of fracture is increased for patients with IBDs versus controls. This result will help to determine the appropriate assessment with early screening and management of osteoporosis. Inflammatory bowel diseases (IBDs), such as Crohn's disease (CD) and ulcerative colitis (UC), are associated with a decreased bone mineral density (BMD). However, the impact on fracture risk is unknown and data are contradictory across studies. In this systematic review and meta-analysis, we aimed to assess the risk of fracture and presence of low BMD in patients with IBDs compared to healthy controls. A systematic search of literature was conducted of MEDLINE, EMBASE, the Cochrane library and abstracts from appropriate scientific congresses. Studies were selected if they compared the incidence of fractures and/or BMD measurement by dual-energy X-ray absorptiometry in patients with IBDs and healthy sex- and age-matched controls. Data were extracted by two independent investigators. Meta-analysis was performed with the inverse variance approach to estimate pooled odds ratios (ORs) and risk ratios (RRs) with their 95% confidence intervals (CIs). Twenty-four studies met the inclusion criteria. On the basis of nine studies, global risk of fracture was increased for patients with IBDs versus controls (RR = 1.38, 95% CI 1.11-1.73; p = 0.005). Fracture risk with IBDs was significantly increased for vertebral fractures (OR = 2.26, 95% CI 1.04-4.90; p < 0.001), but not for any other site. The analysis of 16 studies evaluating BMD showed a significant decrease in mean BMD and Z-scores for IBD patients versus controls at all sites. In our meta-analysis, patients with IBDs have an increased risk of fractures, especially in the spine, and significant decreased BMD at all sites, which suggests the need for identifying high-risk individuals among this population.


Subject(s)
Inflammatory Bowel Diseases/complications , Osteoporosis/etiology , Osteoporotic Fractures/etiology , Bone Density/physiology , Humans , Inflammatory Bowel Diseases/epidemiology , Inflammatory Bowel Diseases/physiopathology , Osteoporosis/epidemiology , Osteoporosis/physiopathology , Osteoporotic Fractures/epidemiology , Osteoporotic Fractures/physiopathology , Risk Assessment/methods
14.
J Hazard Mater ; 324(Pt B): 516-525, 2017 Feb 15.
Article in English | MEDLINE | ID: mdl-27856050

ABSTRACT

Dissolved organic matter (DOM) released from forest leaf litter is potentially effective for the degradation of polycyclic aromatic hydrocarbons (PAHs), yet the inherent mechanism remains insufficiently elucidated. In this study, we investigated the effects of DOM derived from Pinus elliottii and Schima superba leaf litter on the degradation of phenanthrene by the phenanthrene degrading bacterium Sphingobium sp. Phe-1. DOM from different origins and at a large range of concentrations enhanced the degradation rate of phenanthrene. DOM derived from P. elliottii leaf litter decomposed for 12 months used at a concentration of 100mg/L yielded the highest degradation rate (16.9% in 36h) and shortened the degradation time from 48h to 24h. Changes in the composition of DOM during degradation as measured by EEMs-FRI showed that proteins and tyrosine in the DOM supplied readily available nutrients that stimulated biological activity of Phe-1, increasing its growth rate and catechol 2,3-dioxygenase activity. Simultaneously, fulvic acid and humic acid in the DOM enhanced phenanthrene bioavailability by increasing the solubility and mass transfer of phenanthrene, enhancing the uptake kinetics of Phe-1, and increasing the bacteria's direct access to DOM-associated phenanthrene. Humic acid was co-metabolized by Phe-1, resulting in further stimulation of phenanthrene degradation.


Subject(s)
Humic Substances/analysis , Phenanthrenes/analysis , Pinus/chemistry , Plant Leaves/chemistry , Theaceae/chemistry , Water Pollutants, Chemical/analysis , Biodegradation, Environmental , Forests , Models, Theoretical , Phenanthrenes/metabolism , Solubility , Sphingomonadaceae/metabolism , Water Pollutants, Chemical/metabolism
15.
RMD Open ; 2(2): e000226, 2016.
Article in English | MEDLINE | ID: mdl-27651922

ABSTRACT

OBJECTIVES: The RANK/RANKL/osteoprotegerin (OPG) system plays a central role in the pathogenesis of bone erosions in rheumatoid arthritis (RA). The aim of this study was to test the association between 11 single-nucleotide polymorphisms (SNPs) located on RANK, RANKL and OPG genes and anticitrullinated peptide antibody (ACPA) presence or erosions in RA. PATIENTS: This work was performed on three independent samples of French patients with RA: the Etude de Suivi des PolyArthrites Indifférenciées Récentes (ESPOIR) (n=632), Rangueil Midi-Pyrénées (RMP) (n=249) and French Rheumatoid Arthritis Genetic Consortium (FRAGC) (n=590) cohorts. Genotyping: the genotyping of 11 SNPs located on RANK, RANKL and OPG were performed by PCR. STATISTICAL ANALYSES: The association between the genotypes with ACPA or erosions was first tested in the ESPOIR cohort using a χ(2) test and, in the case of significant association, replicated in the RMP and FRACG cohorts. A meta-analysis on the three cohorts was performed using the Mantel-Haenszel method. RESULTS: One SNP on RANK (rs8086340) and three SNPs on RANKL (rs7984870, rs7325635, rs1054016) were significantly associated with ACPA presence, while one SNP on OPG (rs2073618) and one SNP on RANKL (rs7325635) were significantly associated with erosions in the ESPOIR cohort. Following meta-analysis performed on the three samples, the SNP on RANK and the GGG haplotype of the three SNPs located on RANKL were both significantly associated with ACPA presence, while only the SNP on OPG remained significantly associated with erosions. CONCLUSIONS: This study identified one SNP located on RANK, one haplotype on RANKL associated with ACPA presence, and one SNP located on OPG associated with erosions in three different samples of French patients with RA.

16.
BMC Plant Biol ; 16: 17, 2016 Jan 16.
Article in English | MEDLINE | ID: mdl-26772971

ABSTRACT

BACKGROUND: Receptor-like kinases are well-known to play key roles in disease resistance. Among them, the Wall-associated kinases (WAKs) have been shown to be positive regulators of fungal disease resistance in several plant species. WAK genes are often transcriptionally regulated during infection but the pathways involved in this regulation are not known. In rice, the OsWAK gene family is significantly amplified compared to Arabidopsis. The possibility that several WAKs participate in different ways to basal defense has not been addressed. Moreover, the direct requirement of rice OSWAK genes in regulating defense has not been explored. RESULTS: Here we show using rice (Oryza sativa) loss-of-function mutants of four selected OsWAK genes, that individual OsWAKs are required for quantitative resistance to the rice blast fungus, Magnaporthe oryzae. While OsWAK14, OsWAK91 and OsWAK92 positively regulate quantitative resistance, OsWAK112d is a negative regulator of blast resistance. In addition, we show that the very early transcriptional regulation of the rice OsWAK genes is triggered by chitin and is partially under the control of the chitin receptor CEBiP. Finally, we show that OsWAK91 is required for H2O2 production and sufficient to enhance defense gene expression during infection. CONCLUSIONS: We conclude that the rice OsWAK genes studied are part of basal defense response, potentially mediated by chitin from fungal cell walls. This work also shows that some OsWAKs, like OsWAK112d, may act as negative regulators of disease resistance.


Subject(s)
Magnaporthe/physiology , Mitogen-Activated Protein Kinases/metabolism , Oryza/enzymology , Oryza/microbiology , Plant Diseases/microbiology , Plant Proteins/metabolism , Cell Wall/enzymology , Chitin/immunology , Gene Expression , Genes, Plant , Mitogen-Activated Protein Kinases/genetics , Mutation , Oryza/genetics , Oryza/immunology , Plant Diseases/genetics , Plant Diseases/immunology , Plant Proteins/genetics
17.
Sci Total Environ ; 545-546: 40-7, 2016 Mar 01.
Article in English | MEDLINE | ID: mdl-26745291

ABSTRACT

Soil quality is related to soil characteristics such as fertility and contamination. The aim of this study is to assess the effect of land use on these soil characteristics and to confirm the following anthropisation gradient: (i) forest, (ii) grassland, (iii) cultivated, (iv) orchard and vineyard, (v) urban vegetable garden, and (vi) SUITMA (urban, industrial, traffic, mining and military areas). A database comprising the characteristics of 2451 soils has been constituted. In order to compare the topsoils from six contrasting land uses, a principal components analysis (PCA) was performed on nine geochemical variables (C, N, pH, POlsen, total Cd, Cu, Ni, Pb, Zn). The first axis of the PCA is interpreted as a global increase of topsoil metallic elements along the anthropisation gradient. Axis 2 reflects the variability of fertility levels. Human activity increases the pressure on soils along the proposed gradient according to six different distribution patterns. This better knowledge of topsoil quality and its dependence on current land use should therefore help to manage and preserve the soil mantle.

18.
Vision Res ; 126: 192-206, 2016 09.
Article in English | MEDLINE | ID: mdl-26363415

ABSTRACT

Quantitative approaches are part of the understanding of contour integration and the Gestalt law of good continuation. The present study introduces a new quantitative approach based on the a contrario theory, which formalizes the non-accidentalness principle for good continuation. This model yields an ideal observer algorithm, able to detect non-accidental alignments in Gabor patterns. More precisely, this parameterless algorithm associates with each candidate percept a measure, the Number of False Alarms (NFA), quantifying its degree of masking. To evaluate the approach, we compared this ideal observer with the human attentive performance on three experiments of straight contours detection in arrays of Gabor patches. The experiments showed a strong correlation between the detectability of the target stimuli and their degree of non-accidentalness, as measured by our model. What is more, the algorithm's detection curves were very similar to the ones of human subjects. This fact seems to validate our proposed measurement method as a convenient way to predict the visibility of alignments. This framework could be generalized to other Gestalts.


Subject(s)
Attention/physiology , Form Perception/physiology , Pattern Recognition, Visual/physiology , Adult , Algorithms , Female , Gestalt Theory , Humans , Male , Middle Aged , Models, Theoretical , Perceptual Masking , Photic Stimulation/methods , Psychophysics , Young Adult
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