Data about the long-term duration of antibodies after SARS-CoV-2 vaccination are still scarce and are important to design vaccination strategies. In this study, 231 healthcare professionals received ...the two-dose regimen of BNT162b2. Of these, 158 were seronegative and 73 were seropositive at baseline. Samples were collected at several time points. The neutralizing antibodies (NAbs) and antibodies against the nucleocapsid and the spike protein of SARS-CoV-2 were measured. At day 180, a significant antibody decline was observed in seronegative (−55.4% with total antibody assay; −89.6% with IgG assay) and seropositive individuals (−74.8% with total antibody assay; −79.4% with IgG assay). The estimated half-life of IgG from the peak humoral response was 21 days (95% CI: 13–65) in seronegative and 53 days (95% CI: 40–79) in seropositive individuals. The estimated half-life of total antibodies was longer and ranged from 68 days (95% CI: 54–90) to 114 days (95% CI: 87–167) in seropositive and seronegative individuals, respectively. The decline of NAbs was more pronounced (−98.6%) and around 45% of the subjects tested were negative at day 180. Whether this decrease correlates with an equivalent drop in the clinical effectiveness against the virus would require appropriate clinical studies.
Chemokines and their receptors are involved in tumourigenicity and clinicopathological significance of chemokines receptor expression in pancreatic adenocarcinoma (PA) is not fully understood. This ...study was conducted to determine patients' outcome according to the expressions of CXCR4, CXCR7 and HIF-1alpha after resection of PA. Immunohistochemistry for CXCR4, CXCR7 and HIF-1alpha expressions as well as cell proliferative index (Ki-67) was conducted in 71 resected (R0) PA and their 48 related lymph nodes (LN) using tissue microarray. CXCR4 and CXCR7 expressions were positively correlated to HIF-1alpha suggesting a potential role of HIF-1alpha in CXCR4 and CXCR7 transcription activation. Patients with CXCR4(high) tumour expression had shorter OS than those with low expression (median survival: 9.7 vs 43.2 months, P=0.0006), a higher risk of LN metastases and liver recurrence. In multivariate analysis, high CXCR4 expression, LN metastases and poorly differentiated tumour are independent negative prognosis factors. In a combining analysis, patients with a CXCR7(high)/CXCR4(high) corrected tumour had a significantly shorter DFS and OS than patients with a CXCR4(low)/CXCR7(low) corrected tumour. CXCR4 in resected PA may represent a valuable prognostic factor as well as an attractive target for therapeutic purpose.
Non-invasive geophysical methods are often used for detecting near-surface defects and monitoring seepage in river dykes or dams. Between 2008 and 2009, a series of geophysical experiments was ...conducted to detect karst features below the dykes of the Loire River, Orléans, France. Multi-channel analysis of seismic surface waves (MASW) was used to obtain the shear wave velocity (Vs) profile of the subsurface below the dykes. As an effective approach to investigating the structure of the dykes, multi-channel resistivity surveys were also used to evaluate the electrical properties of material inside and under the dykes. This study discusses the exploration strategy and results for several sections of the dyke system. Based on the experimental data, Vs contours are used to geometrically and qualitatively describe the subsurface under the dykes and identify areas of mechanical weakness corresponding to karst features, while resistivity contours allow distinguishing interactions between the karst and the dykes through the identification of areas of downward material movement. Known and unknown anomalies are identified. A practical approach that combines seismic and electric resistivity results is proposed to assess karst presence and sinkhole hazards along the investigated dykes using a susceptibility index referring to the likelihood level of the events. As a validation method, areas of strong karst susceptibility index along the dykes are compared to known collapse event (sinkholes, dyke breaches, etc.) locations, available in databases.
•A series of geophysical experiments was conducted to detect karst features below a dyke system.•The mapping of weak areas in limestone allowed the assessment of karst presence probability level.•Resistivity surveying was useful to detect potential flow of near-surface materials into karsts.•By integrating results, interaction between karsts and the near-surface formations was highlighted.•It then allowed mapping of these sinkhole-susceptible areas with a better accuracy than did former studies.
The Antarctic Silicon Trap Closset, Ivia; Cassarino, Lucie
Frontiers for young minds,
12/2023, Letnik:
11
Journal Article
Odprti dostop
The Southern Ocean, the ocean encircling Antarctica, has been described by explorers as cold, empty, and dangerous. Despite this, it is a paradise for tiny algae called diatoms that are crucial ...players in the regulation of our climate. Why are these tiny organisms so happy in this cold and far away ocean? Diatoms have a solid shell made of a glass-like material called silica, so they need to find silicon in surface waters to build it. The Southern Ocean is the perfect place for diatoms because it is full of silicon compared to the other oceans. This is due to a special phenomenon called the silicon pump, which makes the Southern Ocean a giant trap for silicon. In this article, we point out the central role of the Southern Ocean in the regulation of Earth’s climate and how it controls the distribution of silicon and the wellbeing of diatoms in Antarctic waters.
Abstract We revisit the 3d GLSM computation of the equivariant quantum K-theory ring of the complex Grassmannian from the perspective of line defects. The 3d GLSM onto X = Gr(N c , n f ) is a circle ...compactification of the 3d N $$ \mathcal{N} $$ = 2 supersymmetric gauge theory with gauge group U N c k , k + l N c $$ \textrm{U}{\left({N}_c\right)}_{k,k+l{N}_c} $$ and n f fundamental chiral multiplets, for any choice of the Chern-Simons levels (k, l) in the ‘geometric window’. For k = N c − n f 2 $$ k={N}_c-\frac{n_f}{2} $$ and l = −1, the twisted chiral ring generated by the half-BPS lines wrapping the circle has been previously identified with the quantum K-theory ring QK T (X). We identify new half-BPS line defects in the UV gauge theory, dubbed Grothendieck lines, which flow to the structure sheaves of the (equivariant) Schubert varieties of X. They are defined by coupling N $$ \mathcal{N} $$ = 2 supersymmetric gauged quantum mechanics of quiver type to the 3d GLSM. We explicitly show that the 1d Witten index of the defect worldline reproduces the Chern characters for the Schubert classes, which are written in terms of double Grothendieck polynomials. This gives us a physical realisation of the Schubert-class basis for QK T (X). We then use 3d A-model techniques to explicitly compute QK T (X) as well as other K-theoretic enumerative invariants such as the topological metric. We also consider the 2d/0d limit of our 3d/1d construction, which gives us local defects in the 2d GLSM, the Schubert defects, that realise equivariant quantum cohomology classes.
Nitrogen and gallium co-doped ZnO films have been successfully obtained by a sol-gel technology using spin coating. ZnO:N, ZnO:Ga and co-doped (N, Ga) ZnO films are deposited on silicon and quartz ...substrates. The structural, morphological and optical properties of ZnO:N:Ga thin films are studied depending on the thermal treatments (300–600 °C) and the two dopants: N and Ga. The investigations of the doped ZnO films have been performed by using X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Field Emission Scanning Electron microscope (FESEM) and UV–VIS–NIR spectrophotometry. It has been found that the co-doped (N, Ga) ZnO films are crystallized in the wurtzite structure with no impurity phases. The optical transparency of ZnO:Ga and ZnO:N:Ga films is above 80% in the spectral range of 400–800 nm, revealing a significant improvement compared to undoped ZnO films. Gallium and nitrogen co-doping in ZnO results in the modification of the surface morphologies changing from wrinkle-like (undoped ZnO) to closed packed grained microstructure (ZnO:N:Ga films).
Display omitted
•Successfull sol-gel deposition of co-doped ZnO:N:Ga thin films.•Crystallite sizes, texture coefficients and lattice parameters for ZnO, ZnO:N, ZnO:Ga and ZnO:N:Ga films are studied.•Improved transmittance and enlarged optical band gap of ZnO:Ga and ZnO:N:Ga films.•N and Ga co-doping modifies film morphology from wrinkle network (ZnO) to grained structure of ZnO:N:Ga films.
The relative importance of local, regional and historical factors in controlling the spatial patterns of plant species distribution is still poorly known and challenging for conservation ecology. We ...conducted an empirical study to link the spatial variation of species and environments among forest patches embedded in contrasted agricultural matrices. We compared how forest herb communities responded to spatial environmental gradients and past forest cover. We found low values of β-diversity in both unfragmented and highly fragmented systems, independently from local and regional diversities. As fragmentation increased, the spatial structure of local plant communities was more complex and spatial effects explained an increasing proportion of β-diversity, suggesting that the importance of dispersal limitations increased and played out at broad spatial scales. However, where spatio-temporal isolation of forest patches was the highest, local species assemblages could not be explained, suggesting that the metacommunity functioning was disrupted. Where the historical continuity was high, local environmental characteristics explained a significant amount of species assemblages within metacommunities, suggesting habitat-selection processes. Beta-diversity and variations in presence-absence of species were also influenced by the intensity of landscape management, via the permeability of both forest edges and the matrix. This spatially-explicit analysis of metacommunities revealed that forest fragmentation impacts beta-diversity by altering not only the relative importance of deterministic and stochastic processes, but also the spatial scales at which they act. These results provide empirical support for the conservation of ancient forests and the maintenance of a high connectedness between fragments within agricultural landscapes.
B-branes and supersymmetric quivers in 2d Closset, Cyril; Guo, Jirui; Sharpe, Eric
The journal of high energy physics,
02/2018, Letnik:
2018, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
We study 2d
N
= (0, 2) supersymmetric quiver gauge theories that describe the low-energy dynamics of D1-branes at Calabi-Yau fourfold (CY
4
) singularities. On general grounds, the ...holomorphic sector of these theories — matter content and (classical) superpotential interactions — should be fully captured by the topological
B
-model on the CY
4
. By studying a number of examples, we confirm this expectation and flesh out the dictionary between B-brane category and supersymmetric quiver: the matter content of the supersymmetric quiver is encoded in morphisms between B-branes (that is, Ext groups of coherent sheaves), while the superpotential interactions are encoded in the
A
∞
algebra satisfied by the morphisms. This provides us with a derivation of the supersymmetric quiver directly from the CY
4
geometry. We also suggest a relation between triality of
N
= (0
,
2) gauge theories and certain mutations of exceptional collections of sheaves. 0d
N
= 1 supersymmetric quivers, corresponding to D-instantons probing CY
5
singularities, can be discussed similarly.
Context
Habitat fragmentation and land use intensification are major threats to biodiversity worldwide, affecting both species (SD) and genetic (GD) diversity. It remains unclear whether SD and GD ...respond to the same components of landscape changes and to what extent they correlate in fragmented systems.
Objectives
We explore the role of current and historical patch and landscape features on SD and GD, in and between forest fragments, along a gradient of landscape matrix permeability. We seek the circumstances under which SD and GD correlate.
Methods
Within three contrasted agricultural landscapes of northern France, we assessed vascular plant SD and the GD of two plant species with contrasted life history traits in all forest fragments. Species richness and expected heterozygosity were taken as proxies for SD and GD respectively. Using regression and correlation analyses, we explored relationships between SD/GD and local, landscape and historical factors; and between SD and GD.
Results
When landscape permeability is above a certain threshold, SD and GD appear to be patterned by the same processes, which results in a positive SD-GD correlation. This permeability threshold is species-specific, depending upon species’ dispersal traits and niche width. The SD-GD correlation depends upon current and past landscape permeability, so that the lack of correlation emerges as the rule in weakly permeable landscape matrices, especially when fragments are small.
Conclusions
Landscape matrix permeability and patch features drive SD and GD of vascular plants within and between forest fragments. A generalist, fast-colonizing species better reflects diversity patterns in fragmented forests.
Hedgerows are semi-natural wooded habitats and an important element in agricultural landscapes across Western and North-Western Europe. They reduce erosion, function as carbon sinks and thus provide ...essential ecosystem services. Moreover, they form a structurally diverse ecosystem for numerous taxa and connect otherwise fragmented forest habitats. This study compiled data from the hedgerow-rich oceanic regions of Europe, covering a gradient from Southern Sweden to Northern France, to analyse the influence of management, landscape context and climate variables on the number of herbaceous forest specialists in hedgerows. The species frequencies in hedgerows were related to their functional traits to identify plant characteristics that are beneficial for species dispersal and persistence in hedgerows. Our results show that numerous forest plant species, but not all, can thrive in hedgerows. Those are likely thermophilic, tolerant against regular disturbance and able to disperse efficiently. Hedgerows in regions that are warm or that are impacted by heat and drought events contain fewer forest species. Intensive adjacent land-use had a negative impact on forest species richness, while the surrounding forest cover was not significantly important. In congruence with previous regional studies, wider hedgerows contain more forest species, which is most likely caused by a more effective buffering of the microclimate. Thus, hedgerow width gains in importance in times of climate change and increasing extreme weather events. It is a key factor for habitat quality also on a European scale that needs to be considered for future management strategies.
•Numerous forest plant species, but not all, can thrive in hedgerows across Europe.•Frequent species are likely tolerant against high temperatures and regular disturbance.•Heat and drought events are linked to a reduced forest plant richness in hedgerows.•Hedgerow width is a key factor for habitat quality.
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