Evaluation of vegetation post-fire resilience in the Alpine region using descriptors derived from MODIS spectral index time series

In this study a method based on the analysis of MODerate-resolution Imaging Spectroradiometer (MODIS) time series is proposed to estimate the post-fire resilience of mountain vegetation (broadleaf forest and prairies) in the Italian Alps. Resilience is defined herewith as the ability of a dynamical system to counteract disturbances. It can be quantified by the amount of time the disturbed system takes to resume, in statistical terms, an ecological functionality comparable with its undisturbed behavior. Satellite images of the Normalized Difference Vegetation Index (NDVI) and of the Enhanced Vegetation Index (EVI) with spatial resolution of 250m and temporal resolution of 16 days in the 2000-2012 time period were used. Wildfire affected areas in the Lombardy region between the years 2000 and 2010 were analysed. Only large fires (affected area >40ha) were selected. For each burned area, an undisturbed adjacent control site was located. Data pre-processing consisted in the smoothing of MODIS time series for noise removal and then a double logistic function was fitted. Land surface phenology descriptors (proxies for growing season start/end/length and green biomass) were extracted in order to characterize the time evolution of the vegetation. Descriptors from a burned area were compared to those extracted from the respective control site by means of the one-way analysis of variance. According to the number of subsequent years which exhibit statistically meaningful difference between burned and control site, five classes of resilience were identified and a set of thematic maps was created for each descriptor. The same method was applied to all 84 aggregated events and to events aggregated by main land cover. EVI index results more sensitive to fire impact than NDVI index. Analysis shows that fire causes both a reduction of the biomass and a variation in the phenology of the Alpine vegetation. Results suggest an average ecosystem resilience of 6-7 years. Moreover, broadleaf forest and prairies show different post-fire behavior in terms of land surface phenology descriptors. In addition to the above analysis, another method is proposed, which derives from the qualitative theory of dynamical systems. The (time dependent) spectral index of a burned area over the period of one year was plotted against its counterpart from the control site. Yearly plots (or scattergrams) before and after the fire were obtained. Each plot is a sequence of points on the plane, which are the vertices of a generally self-intersecting polygonal chain. Some geometrical descriptors were obtained from the yearly chains of each fire. Principal Components Analysis (PCA) of geometrical descriptors was applied to a set of case studies and the obtained results provide a system dynamics interpretation of the natural process.JRC.H.3 - Forest Resources and Climat

Loss to follow-up and re-linkage to care in a single cohort study: who do we re-link to care?

open6noPurpose: Describe the HIV-infected patients lost to follow-up (LTFU) at our Centre and identify variables that might predict a subsequent re-linkage to care (RLTC). Method: We conducted a single center, retrospective study including patients followed at the Infectious Diseases Clinic of San Martino Policlinic Hospital, Genoa. LTFU was defined as missing appointments for both visits and exams for≥12 months. All patients LTFU during the year 2015, who were already in care at the beginning of the previous year, were included. All RLTC up to December 2018 were registered. Data were retrieved through medical records and the electronic MedInfo database. The possible association of different variables with RLTC was assessed through univariable logistic regression model. Results: Sixty-three patients were enrolled, of whom 32 (50.8%) re-entered care. Median time between LTFU and RLTC was 1 year (range 1–3 years). Median viral load at RLTC was 46.5 copies/mL (IQR 0–1500 copies/mL). Seventeen patients (53.1%) had undetectable viral load (HIV RNA<50 copies/mL) at RLTC. Other characteristics of the two populations are illustrated in table 1. At univariable logistic regression, only age showed a statistically significant association with RLTC (OR 0.9; 95% CI 0.9–1.0; p=0.033). No multivariable analysis was performed due to the small sample size. Conclusion: To maintain linkage to care is crucial in the cascade of care of HIV-infected patients. Half of the patients we LTFU in 2015 re-entered care after a median time of 1 year; half of them had an undetectable viral load upon re-linkage, testifying that they carried on antiretroviral treatment despite the apparent LTFU. Younger age was the only factor we found could predict the re-entrance in care. Limitations to the interpretability of our data stem from the small sample size and the retrospective design of the study, with a consistent amount of missing data.openLaura Magnasco, Sara Mora, Mauro Giacomini, Giovanni Sarteschi, Rachele Pincino, Antonio Di BiagioMagnasco, Laura; Mora, Sara; Giacomini, Mauro; Sarteschi, Giovanni; Pincino, Rachele; DI BIAGIO, Antoni

Loss of accumulation zone exposes dark ice and drives increased ablation at Weißseespitze, Austria

In recent years, firn and summer snow cover has decreased on Alpine glaciers, exposing larger areas of ice at higher elevations. This reduces albedo and leads to increased melt. To understand mass loss in former accumulation areas under conditions of rapid glacier recession, it is important to constrain the possible range of ice albedo in newly firn free regions, the duration of ice exposure, and the albedo-ablation connection. We combine data from an on-ice weather station (3492 m.a.s.l.), ablation stakes, and remote sensing derived albedo to provide an overview of albedo and ablation in the summit region of Weißseespitze, the high-point of Gepatschferner (Austria), from 2018 to 2024. Before 2022, low albedo (<0.4) occurred on 3 to 8 days per year. In 2022, 37 days of low albedo conditions were recorded and albedo dropped below previously observed minima of around 0.30 to values similar to those of the surrounding rock. Albedo remained very low in 2023 and 2024. Ice ablation at the stakes generally increased with the duration of ice exposure, reaching up to -1.6 m w.e. in high-melt years. Sensitivity experiments indicate that a five day period of very low albedo conditions (<0.20) results in 31 % more modeled surface melt if it occurs in late July compared to early September, highlighting temporal variability in the impact of ice exposure. The unique Weißseespitze dataset provides a starting point for further studies linking causes and effects of albedo changes in former accumulation zones

mapping the suitability for ice core drilling of glaciers in the european alps and the asian high mountains

ABSTRACTIce cores from mid-latitude mountain glaciers provide detailed information on past climate conditions and regional environmental changes, which is essential for placing current climate change into a longer term perspective. In this context, it is important to define guidelines and create dedicated maps to identify suitable areas for future ice-core drillings. In this study, the suitability for ice-core drilling (SICD) of a mountain glacier is defined as the possibility of extracting an ice core with preserved stratigraphy suitable for reconstructing past climate. Morphometric and climatic variables related to SICD are selected through literature review and characterization of previously drilled sites. A quantitative Weight of Evidence method is proposed to combine selected variables (i.e. slope, local relief, temperature and direct solar radiation) to map the potential drilling sites in mid-latitude mountain glaciers. The method was first developed in the European Alps and then applied to the Asian High Mountains. Model performances and limitations are discussed and first indications of new potential drilling sites in the Asian High Mountains are provided. Results presented here can facilitate the selection of future drilling sites especially on unexplored Asian mountain glaciers towards the understanding of climate and environmental changes

Persistence of Unintegrated HIV DNA Associates With Ongoing NK Cell Activation and CD34+DNAM-1brightCXCR4+ Precursor Turnover in Vertically Infected Patients Despite Successful Antiretroviral Treatment

none11noThe quantification of proviral DNA is raising interest in view of clinical management and functional HIV eradication. Measures of all unintegrated HIV DNA (uDNA) forms in infected reservoir cells provides information on recent replication events that is not found from other proviral DNA assays. To evaluate its actual relevance in a cohort of perinatally-infected adult HIV patients (PHIV), we studied how peripheral blood mononuclear cell uDNA levels correlated with total HIV DNA (tDNA) and with overall replication or innate immune control parameters including NK cell activation/exhaustion and lymphoid turnover. Twenty-two PHIV were included, with successfully controlled HIV (HIV RNA <50 copies/mL) on combined antiretroviral therapy for mean of 8.7 ± 3.9 years. uDNA accounted for 16 [5.2-83.5] copies/µg and was strongly correlated with tDNA (ρ=0.700, p=0.001). Flow cytometric analysis of peripheral NK cells showed that CD69 expression was directly correlated uDNA (p=0.0412), but not with tDNA. Interestingly, CD56-CD16+NK cells which include newly described inflammatory precursors and terminally differentiated cells were directly correlated with uDNA levels (p<0.001), but not with tDNA, and an inverse association was observed between the proportion of NKG2D+ NK cells and uDNA (ρ=-0.548, p=0.015). In addition, CD34+DNAM-1brightCXCR4+ inflammatory precursor frequency correlated directly with uDNA levels (ρ=0.579, p=0.0075). The frequencies of CD56-CD16+ and CD34+DNAM-1brightCXCR4+ cells maintained association with uDNA levels in a multivariable analysis (p=0.045 and p=0.168, respectively). Thus, control of HIV-1 reservoir in aviremic patients on ART is an active process associated with continuous NK cell intervention and turnover, even after many years of treatment. Quantification of linear and circular uDNA provides relevant information on the requirement for ongoing innate immune control in addition to ART, on recent replication history and may help stratify patients for functional HIV eradication protocols with targeted options.openTaramasso, Lucia; Bozzano, Federica; Casabianca, Anna; Orlandi, Chiara; Bovis, Francesca; Mora, Sara; Giacomini, Mauro; Moretta, Lorenzo; Magnani, Mauro; Di Biagio, Antonio; De Maria, AndreaTaramasso, Lucia; Bozzano, Federica; Casabianca, Anna; Orlandi, Chiara; Bovis, Francesca; Mora, Sara; Giacomini, Mauro; Moretta, Lorenzo; Magnani, Mauro; Di Biagio, Antonio; De Maria, Andre

Mapping surface features of an Alpine glacier through multispectral and thermal drone surveys

Glacier surfaces are highly heterogeneous mixtures of ice, snow, light-absorbing impurities and debris material. The spatial and temporal variability of these components affects ice surface characteristics and strongly influences glacier energy and mass balance. Remote sensing offers a unique opportunity to characterize glacier optical and thermal properties, enabling a better understanding of different processes occurring at the glacial surface. In this study, we evaluate the potential of optical and thermal data collected from field and drone platforms to map the abundances of predominant glacier surfaces (i.e., snow, clean ice, melting ice, dark ice, cryoconite, dusty snow and debris cover) on the Zebrù glacier in the Italian Alps. The drone surveys were conducted on the ablation zone of the glacier on 29 and 30 July 2020, corresponding to the middle of the ablation season. We identified very high heterogeneity of surface types dominated by melting ice (30% of the investigated area), dark ice (24%), clean ice (19%) and debris cover (17%). The surface temperature of debris cover was inversely related to debris-cover thickness. This relation is influenced by the petrology of debris cover, suggesting the importance of lithology when considering the role of debris over glaciers. Multispectral and thermal drone surveys can thus provide accurate high-resolution maps of different snow and ice types and their temperature, which are critical elements to better understand the glacier’s energy budget and melt rates

Is it still worthwhile to perform quarterly CD4+ T lymphocyte cell counts on HIV-1 infected stable patients?

Background: In the last twenty years routine T CD4+ lymphocyte (CD4) cell count has proved to be a key factor to determine the stage of HIV infection and start or discontinue of prophylaxis for opportunistic infections. However, several studies recently showed that in stable patients on cART a quarterly CD4 cell count monitoring results in limited (or null) clinical relevance. The research is intended to investigate whether performing quarterly CD4 cell counts in stable HIV-1 patients is still recommendable and to provide a forecast of the cost saving that could be achieved by reducing CD4 monitoring in such a category of patients. Methods: The study is based on data referring to all HIV-infected patients &gt; 18 years of age being treated at two infectious diseases units located in the metropolitan area of Genoa, Italy. The probability of CD4 cell counts dropping below a threshold value set at 350 cells/mm3 is assessed using confidence intervals and Kaplan-Meier survival estimates, whereas multivariate Cox analysis and logistic regression are implemented in order to identify factors associated with CD4 cell count falls below 350 cells/mm3. Results: Statistical analysis reveals that among stable patients the probability of maintaining CD4 &gt;350 cell/mm3 is more than 98%. Econometric models indicate that HCV co-infection and HIV-RNA values &gt;50 copies/mL in previous examinations are associated with CD4 falls below 350 cells/mm3. Moreover, results suggest that the cost saving that could be obtained by reducing CD4 examinations ranges from 33% to 67%. Conclusions: Empirical findings show that patients defined as stable at enrollment are highly unlikely to experience a CD4 value &lt;350 cell/mm3 in the space/arc of a year. The research supports a recommendation for annual CD4 monitoring in stable HIV-1 patients

Prevalence of Viral Hepatitis in Unselected, Consecutively Enrolled Patients Hospitalised for SARS-CoV-2

Diagnosing people living with chronic viral hepatitis is challenging due to the absence of symptoms as long as liver decompensated cirrhosis come out. The aim of this retrospective study was to evaluate the prevalence of HBV and/or HCV infections in a non-selected population, hospitalised for SARS-CoV-2 infection in a tertiary care hospital in Northern Italy. During the study period 1,429 patients were admitted to hospital for SARS-CoV-2 infection, serologic tests for HBV and/or HCV were available for 382 (27%) patients and 3 were excluded due to their previous known serologic status. Among 379 patients, 235 (62%) were male, median age was 70 years (range 21-103), 360 (95%) were Caucasian. Among them, 372/379 (98%) were screened for HBsAg, 320/379 (84%) for HBcAb. HBsAg was positive in 2/372 (0.5%, 95% CI 0.0006-0.02) patients (only in one HBV-DNA was performed that was negative), while HBcAb was found positive in 55/320 (17%, 95% CI 0.13-0.22). Among 370/379 (98%) patients screened for HCV, 11/370 (3%, 95% CI 0.02-0.05) had positive HCV-Ab. Five out of 11 (45%) were tested for HCV-RNA that resulted positive in two patients (0.5%, 95% CI 0.0006-0.02). Considering this data, even though the screening was performed in only 27% of study population, a tailored screening in people with known risk factors for hepatitis might be preferable to universal screening in low prevalence areas. Also a prompt diagnostic workout should begin in case of clinical or laboratory suspicion of hepatitis and in those starting immunosuppressive treatments