tt-Martin boundary of killed random walks in the quadrant

We compute the $t$-Martin boundary of two-dimensional small steps random walks killed at the boundary of the quarter plane. We further provide explicit expressions for the (generating functions of the) discrete $t$-harmonic functions. Our approach is uniform in $t$, and shows that there are three regimes for the Martin boundary.Comment: 18 pages, 2 figures, to appear in S\'eminaire de Probabilit\'e

Determinants of methicillin-susceptible Staphylococcus aureus native bone and joint infection treatment failure: a retrospective cohort study.

BACKGROUND: Although methicillin-susceptible Staphylococcus aureus (MSSA) native bone and joint infection (BJI) constitutes the more frequent clinical entity of BJI, prognostic studies mostly focused on methicillin-resistant S. aureus prosthetic joint infection. We aimed to assess the determinants of native MSSA BJI outcomes. METHODS: Retrospective cohort study (2001-2011) of patients admitted in a reference hospital centre for native MSSA BJI. Treatment failure determinants were assessed using Kaplan-Meier curves and binary logistic regression. RESULTS: Sixty-six patients (42 males [63.6%]; median age 61.2 years; interquartile range [IQR] 45.9-71.9) presented an acute (n = 38; 57.6%) or chronic (n = 28; 42.4%) native MSSA arthritis (n = 15; 22.7%), osteomyelitis (n = 19; 28.8%) or spondylodiscitis (n = 32; 48.5%), considered as "difficult-to-treat" in 61 cases (92.4%). All received a prolonged (27.1 weeks; IQR, 16.9-36.1) combined antimicrobial therapy, after surgical management in 37 cases (56.1%). Sixteen treatment failures (24.2%) were observed during a median follow-up period of 63.3 weeks (IQR, 44.7-103.1), including 13 persisting infections, 1 relapse after treatment disruption, and 2 super-infections. Independent determinants of treatment failure were the existence of a sinus tract (odds ratio [OR], 5.300; 95% confidence interval [CI], 1.166-24.103) and a prolonged delay to infectious disease specialist referral (OR, 1.134; 95% CI 1.013-1.271). CONCLUSIONS: The important treatment failure rate pinpointed the difficulty of cure encountered in complicated native MSSA BJI. An early infectious disease specialist referral is essential, especially in debilitated patients or in presence of sinus tract

Dilemma of nitrogen management for future food security in sub-Saharan Africa – a review

Article purchased; Published online: 13 July 2017Food security entails having sufficient, safe, and nutritious food to meet dietary needs. The need to optimise nitrogen (N) use for nutrition security while minimising environmental risks in sub-Saharan Africa (SSA) is overdue. Challenges related to managing N use in SSA can be associated with both insufficient use and excessive loss, and thus the continent must address the ‘too little’ and ‘too much’ paradox. Too little N is used in food production (80% of countries have N deficiencies), which has led to chronic food insecurity and malnutrition. Conversely, too much N load in water bodies due mainly to soil erosion, leaching, limited N recovery from wastewater, and atmospheric deposition contributes to eutrophication (152 Gg N year–1 in Lake Victoria, East Africa). Limited research has been conducted to improve N use for food production and adoption remains low, mainly because farming is generally practiced by resource-poor smallholder farmers. In addition, little has been done to effectively address the ‘too much’ issues, as a consequence of limited research capacity. This research gap must be addressed, and supportive policies operationalised, to maximise N benefits, while also minimising pollution. Innovation platforms involving key stakeholders are required to address N use efficiency along the food supply chain in SSA, as well as other world regions with similar challenges

Broad-Spectrum Antibiotic Treatment and Subsequent Childhood Type 1 Diabetes: A Nationwide Danish Cohort Study

International audienceBackground: Treatment with antibiotics in early childhood is effective for bacterial infections but may have long-term side effects. We evaluated the effect of broad-spectrum antibiotics treatment during the first two years of life in association with mode of delivery on subsequent onset of childhood type 1 diabetes.Methods: A Danish Nationwide cohort study included all singletons born during 1997-2010. Five national registers provided information on antibiotic redemption, outcome and confounders. The risk of type 1 diabetes with onset before the age of 15 years was assessed by Cox regression. A total of 858,201 singletons contributed 5,906,069 person- years, during which 1,503 children were diagnosed with type 1 diabetes.Results: Redemption of broad-spectrum antibiotics during the first two years of life was associated with an increased rate of type 1 diabetes during the following 13 years of life (HR 1.13; 95% CI 1.02 to 1.25), however, the rate was modified by mode of delivery. Broad- spectrum antibiotics were associated with an increased rate of type 1 diabetes in children delivered by either intrapartum cesarean section (HR 1.70; 95% CI 1.15 to 2.51) or prelabor cesarean section (HR 1.63; 95% CI 1.11 to 2.39), but not in vaginally delivered children. Number needed to harm was 433 and 562, respectively. The association with broad-spectrum antibiotics was not modified by parity, genetic predisposition or maternal redemption of antibiotics during pregnancy or lactation.Conclusions: Redemption of broad-spectrum antibiotics during infancy is associated with an increased risk of childhood type 1 diabetes in children delivered by cesarean section

Agrarian Dynamics and Landscape Dynamics in the Tleta Watershed, Western Rif (Morocco).

Le Tangérois est en plein évolution socioéconomique avec le développement des zones franches et l’installation d’une nouvelle population. Les besoins en eau et en produits agricoles augmentent. L’urbanisation et l’industrialisation font que la terre change d’utilisation et de fonction.Ces changements impacteraient le comportement hydrologique du bassin du Tleta (17 700 ha) qui alimente le barrage Ibn Batouta ; source importante d’eau pour le Tangérois. L’hypothèse posée est que ces changements paysagers impactent la production en eau, l’érosion des sols et la productivité des terres. C’est la finalité principale du projet de recherche ALMIRA dans lequel s’insère cette étude. Elle vise à contribuer à la vérification de cette hypothèse en analysant la dynamique agraire et paysagère dans le Tleta. Le diagnostic du bassin Tleta a permis un zonage agroécologique des terres et une description des systèmes d’exploitation agricole (56 exploitations enquêté). Huit quadrats de 1,75 km² en moyenne ont été choisis pour analyser la dynamique des occupations des terres et des parcellaires entre 2000 et 2015 à partir de l’exploitation de cartes des occupations produites à différentes dates et d’images Google de 2003, 2009 et 2015. Pour chaque quadra, le parcellaire a été digitalisé. L’étude a confirmé l’intense évolution des espaces dans le Tleta. Les facteurs de changement importants sont le développement économique, l’implantation de la ville nouvelle de Chrafate, l’apport de capitaux extérieurs, l’exode des jeunes, le développement de l’arboriculture (Plan Maroc Vert) et la valorisation du matorral. L’analyse des quadrats a montré que la part des parcelles avec bâti varie de 0 à 30% ; celles avec haie de 0 à 90%; la taille médiane des parcelles est inférieure à 0,5 ha mais varie de quelques m² à 2 ha ; la part du matorral varie entre 2 et 57%. Le système d’exploitation dominant est la polyculture-polyélevage. La taille moyenne d’une exploitation est de 7,7ha répartie sur 6 parcelles. 50% des exploitations ont une taille de 5 à 10 ha. Elles produisent des céréales (blé, orge, avoine), du sorgho et des légumineuses (fève, lentilles, pois chiche), destinées à l’autoconsommation et à l’élevage. La rotation dominante est culture (céréales)/jachère qui sert de pâture au cheptel. La plantation de l’olivier est récemment développée. Le troupeau moyen est composé de 4 bovins, 3 ovins et 3 caprins. Cette étude a posé les bases d’une analyse prospective du bassin : comment ces évolutions vont-elles se combiner à l’horizon 2040 ? Quels seront les impacts sur l’économie agricole, l’érosion et la fourniture d’eau pour le barrage ? Mots clés : Dynamique agraire, Dynamique paysagère, Bassin versant Tleta, Rif Occidental, MarocThe Tangérois region is into full socio-economic evolution with the development of free zones and the establishment of a new population. The requirements of water and agricultural produce increase. The urbanization and industrialization cause the land to change use and function. These changes would affect the hydrological behavior of Tleta watershed (17 700 ha), which feeds Ibn Batouta dam; a significant source of water for the Tangérois. The assumption sit for is that these landscape changes affect the production of water, soil erosion and the productivity of land. It is the principal purpose of the ALMIRA research project, within which this study is being implemented. It aims at contributing to check this assumption by analyzing agrarian and landscape dynamics in Tleta. The diagnosis of the Tleta watershed allowed the agroecological zoning of land and the description of the agricultural farming systems (56 surveyed farms). Eight quadrats (of 1,75 km² on average) were selected to analyze the dynamics of land use and parcellar between 2000 and 2015 starting from the exploitation of land use maps produced on different dates and Google images of quadrats selected for 2003, 2009 and 2015. For each quadrat, the parcellar was digitalized. The study confirmed the intense evolution of spaces in Tleta. The significant factors of change are the economic development, the establishment of the new city of Chrafate, the contributions of external capital, the exodus of young people, the development of tree crops (Morocco Green Plan) and the valorization of matorral. The analysis of quadrats showed that the share of parcels with built environment varies from 0 to 30%; those with hedge from 0 to 90%; the median size of the parcels is lower than 0.5 ha but varies from some m² to 2 ha; the share of matorral varies between 2 and 57%. The dominating farming system is the mixed-farming-livestock. The average size is 7.7 ha, distributed on six parcels. 50% of the farms have a size from 5 to 10 ha. They produce cereals (wheat, barley, oats), sorghum and leguminous plants (beans, lentils, chickpea), intended for auto consumption and livestock. Dominant crop rotation is cereal/fallow, used as pasture for livestock. The olive-tree plantation is recently developed. The average animal herd is composed of four cattle, three sheep and three goats. This study posed the bases of a prospective analysis of the watershed: How these evolutions will combine by 2040? What would be the impacts on agricultural economics, erosion and the supply of water for the dam? Key words: Agrarian dynamics, Landscape dynamics, Tleta watershed, Western Rif, Morocc

Association between ATN profiles and mortality in a clinical cohort of patients with cognitive disorders

BACKGROUND: Alzheimer's disease (AD) is the 5th leading cause of death in people 65 years and older. The ATN classification reflects a biological definition of AD pathology with markers of Aβ deposition (A), pathologic tau (T), and neurodegeneration (N). Little is known about the relationship between ATN status and the risk of mortality, leading us to examine this association in a relatively large population of patients seen at a memory clinic for cognitive disorders. METHODS: Data were drawn from the BioCogBank Study, including patients seen for cognitive disorders in Lariboisiere Hospital (Paris, France), followed up to 15 years. All participants underwent a lumbar puncture for an assessment of the levels of CSF tau (tau), phosphorylated tau (p-tau181), and β-amyloid 42 peptide (Aβ42). Vital status on July 1, 2020, was recorded for each participant using the national mortality register. Individuals were categorized according to their ATN profiles based on CSF Aβ42 or Aβ42/40 ratio, p-tau181, and tau. Kaplan-Meier and multivariate Cox analyses were performed with A-T-N - participants as the reference using a short (5 years) and long follow-up (15 years). RESULTS: Of the 1353 patients in the study (mean age: 68 years old, 53% of women, mean MMSE score: 22.6), 262 died during the follow-up. At 5 years of follow-up, A-T-N + individuals had the highest risk of mortality in Kaplan-Meier and adjusted Cox analyses [HR (95% CI) = 2.93 (1.31-6.56)]. At 15 years of follow-up, patients in the AD spectrum had a higher mortality risk with a gradient effect for biomarker positivity: A-T + [HR = 1.63 (1.04-2.55)], A + T - [HR = 2.17 (1.44-3.26)], and A + T + individuals [HR = 2.38 (1.66-3.39)], compared to A-T-N - patients. Adjustments on potential confounders had little impact on these associations. CONCLUSION: This study shows ATN profiles to be associated with mortality in a relatively large patient cohort based on a memory clinic. Patients with isolated evidence of neurodegeneration had a higher mortality rate in the short follow-up, and patients with the AD profile had the highest mortality rate in the long follow-up

CSF levels of the BACE1 substrate NRG1 correlate with cognition in Alzheimer’s disease

Background: The presynaptic protein neuregulin1 (NRG1) is cleaved by beta-site APP cleaving enzyme 1 (BACE1) in a similar way as amyloid precursor protein (APP) NRG1 can activate post-synaptic receptor tyrosine-protein kinase erbB4 (ErbB4) and was linked to schizophrenia. The NRG1/ErbB4 complex is neuroprotective, can trigger synaptogenesis and plasticity, increases the expression of NMDA and GABA receptors, and can induce neuroinflammation. This complex can reduce memory formation. In Alzheimer’s disease (AD) brains, NRG1 accumulates in neuritic plaques. It is difficult to determine if NRG1 has beneficial and/or detrimental effects in AD. BACE1 levels are increased in AD brains and cerebrospinal fluid (CSF) and may lead to enhanced NRG1 secretion, but no study has assessed CSF NRG1 levels in AD and mild cognitive impairment (MCI) patients. / Methods: This retrospective study included 162 patients suffering from AD dementia (54), MCI with progression to AD dementia (MCI-AD) (27), non-AD MCI (30), non-AD dementias (30), and neurological controls (27). All patients had neurological examinations, brain MRI, and neuropsychological evaluations. After written informed consent and using enzyme-linked immunosorbent assays (ELISAs), CSF samples were evaluated for Aβ1–42, Aβ1–40, total tau (T-tau), phosphorylated tau on threonine 181 (P-tau), BACE1, growth-associated protein 43 (GAP 43), neurogranin (Ng), and NRG1. / Results: Levels of NRG1 were significantly increased in the CSF of AD (+ 36%) and MCI-AD (+ 28%) patients compared to neurological controls and also non-AD MCI and non-AD dementias. In addition, in AD and MCI-AD patients, NRG1 levels positively correlated with Aβ1–42 but not with T-tau, P-tau, and BACE1 levels and negatively correlated with MMSE scores. A longitudinal follow-up study of AD patients revealed a trend (p = 0.08) between CSF NRG1 levels and cognitive decline. In the overall population, NRG1 correlated with MMSE and the synaptic biomarkers GAP 43 and neurogranin. / Conclusions: Our results showed that CSF NRG1 levels are increased in AD and MCI-AD as compared to controls and other dementias. CSF NRG1 levels are associated with cognitive evolution, and a major outcome of our findings is that synaptic NRG1 could be involved in the pathophysiology of AD. Modulating brain NRG1 activity may represent a new therapeutic target in AD

Full-length and C-terminal neurogranin in Alzheimer's disease cerebrospinal fluid analyzed by novel ultrasensitive immunoassays

Background: Neurogranin (Ng) is a neuron-specific and postsynaptic protein that is abundantly expressed in the brain, particularly in the dendritic spine of the hippocampus and cerebral cortex. The enzymatic cleavage of Ng produces fragments that are released into cerebrospinal (CSF), which have been shown to be elevated in Alzheimer’s disease (AD) patients and predict cognitive decline. Thus, quantification of distinctive cleavage products of Ng could elucidate different features of the disease. Methods: In this study, we developed novel ultrasensitive single molecule array (Simoa) assays for measurement of full-length neurogranin (FL-Ng) and C-terminal neurogranin (CT-Ng) fragments in CSF. The Ng Simoa assays were evaluated in CSF samples from AD patients (N = 23), mild cognitive impairment due to AD (MCI-AD) (N = 18), and from neurological controls (N = 26). Results: The intra-assay repeatability and inter-assay precision of the novel methods had coefficients of variation below 7% and 14%, respectively. CSF FL-Ng and CSF CT-Ng median concentrations were increased in AD patients (6.02 ng/L, P < 0.00001 and 452 ng/L, P = 0.00001, respectively) and in patients with MCI-AD (5.69 ng/L, P < 0.00001 and 566 ng/L, P < 0.00001) compared to neurological controls (0.644 ng/L and 145 ng/L). The median CSF ratio of CT-Ng/FL-Ng were decreased in AD patients (ratio = 101, P = 0.008) and in patients with MCI-AD (ratio = 115, P = 0.016) compared to neurological controls (ratio = 180). CSF of FL-Ng, CT-Ng, and ratio of CT-Ng/FL-Ng could each significantly differentiate AD patients from controls (FL-Ng, AUC = 0.907; CT-Ng, AUC = 0.913; CT-Ng/FL-Ng, AUC = 0.775) and patients with MCI-AD from controls (FL-Ng, AUC = 0.937; CT-Ng, AUC = 0.963; CT-Ng/FL-Ng, AUC = 0.785). Conclusions: Assessments of the FL-Ng and CT-Ng levels in CSF with the novel sensitive immunoassays provide a high separation of AD from controls, even in early phase of the disease. The novel Ng assays are robust and highly sensitive and may be valuable tools to study synaptic alteration in AD, as well as to monitor the effect on synaptic integrity of novel drug candidates in clinical trials

Growth of Cu2SnS3 thin films by solid reaction under sulphur atmosphere

Cu2SnS3 thin film have been synthesized by solid state reaction under vapour sulphur pressure at 530 °C, during 6 h, via a sequentially deposited copper and tin layers Cu/Sn/Cu…Sn/Cu/Sn. The structure and the composition were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA). X-ray diffraction revealed that as the deposited film crystallizes in the cubic structure and the crystallites exhibit preferential 111 orientation of the grains. Moreover, EPMA analysis confirmed that the obtained film is stoichiometric. The SEM study shows the presence of spherical particles of ≈100–120 nm diameters. The optical absorption coefficient and band gap of the film were estimated by means of transmission and reflection optical measurements at room temperature. A relatively high absorption coefficient in the range of 104 cm−1 was indeed obtained and the band gap value is of the order of 1.1 eV. On the other hand, the electrical conductivity of Cu2SnS3 film prepared in the present experiment is suitable for fabricating a thin film solar cell based on not cheaper and environmental friendly material