Modelling Permafrost Distribution using the Temperature at Top of Permafrost Model in the Boreal Forest Environment of Whatì, NT.

Current permafrost models in Canadian boreal forests are generally low spatial resolution as they cover regional or continental scales. This study aims to understand the viability of creating a temperature at top of permafrost (TTOP) model on a local scale in the boreal wetland environment of Whatì, Northwest Territories from short-term field-collected temperature data. The model utilizes independent variables of vegetation, topographic positioning index and elevation, with the dependent variables being ground surface temperature collected from 60 ground temperature nodes (GTN) and 1.5 m air temperature collected from 10 temperature stations. In doing this the study investigates the relationship vegetation and disturbance have on ground temperature and permafrost distribution. The model predicts that 31 % of the ground is underlain by permafrost, based on a mean annual temperature at TTOP of < 0 °C. This model shows an accuracy of 62.5 % when compared to Cryotic Assessment Sites (CAS). Most inaccuracies, showing the limitation of the TTOP model, came from peat plateaus that had undergone burn in the most recent forest fire in 2014. These resulted in out of equilibrium permafrost and climatic conditions which TTOP cannot handle well. Commonly permafrost mapping places Whatì in the extensive discontinuous zone estimating that between 50 % to 90 % of the ground is underlain by permafrost. The study shows that a climatically driven TTOP model calibrated with CAS can be used to illustrate ground temperature heterogeneity from short-term data in boreal forest wetland environments. However, this approach likely underestimates permafrost extent and is perhaps not the best-suited modelling choice for near-surface permafrost, which is currently out of equilibrium with the current climat

Modelling air, ground surface and permafrost temperature variability across four dissimilar valleys, Yukon, Canada

Spatial maps of the air and ground thermal regime were generated for four Yukon valleys. The aim was to model air, ground surface and ground temperature (at fine spatial resolution) using locally measured inverted surface lapse rates (SLR), to better predict temperature along an elevation gradient. These local models were then compared to a regional permafrost probability model, which utilized differing inversion assumptions, as well as circumpolar and national models generated without considering inversions. Overall, permafrost probability in the regional model matched well with the local models where assumptions of treeline and inverted SLRs held true. When normal SLRs were assumed, permafrost presence was overestimated in each valley. This discrepancy was greatest at high elevations where permafrost was predicted to be coldest and most widespread. However, the difference between valleys was dependent on surface and subsurface characteristics such as higher snow cover, mature forest or thick organic layers showed a greater disassociation from the air temperature overall. Appropriate characterization of the SLR is essential for accurate predictions of the ground thermal regime’s spatial distribution and permafrost presence. These models also provide a starting point for better predictions of warming in these valleys and other areas subject to inversions of similar magnitudes

Exosomes as potent cell-free peptide-based vaccine. II. Exosomes in CpG adjuvants efficiently prime naive Tc1 lymphocytes leading to tumor rejection.

Item does not contain fulltextIdeal vaccines should be stable, safe, molecularly defined, and out-of-shelf reagents efficient at triggering effector and memory Ag-specific T cell-based immune responses. Dendritic cell-derived exosomes could be considered as novel peptide-based vaccines because exosomes harbor a discrete set of proteins, bear functional MHC class I and II molecules that can be loaded with synthetic peptides of choice, and are stable reagents that were safely used in pioneering phase I studies. However, we showed in part I that exosomes are efficient to promote primary MHC class I-restricted effector CD8(+) T cell responses only when transferred onto mature DC in vivo. In this work, we bring evidence that among the clinically available reagents, Toll-like receptor 3 and 9 ligands are elective adjuvants capable of triggering efficient MHC-restricted CD8(+) T cell responses when combined to exosomes. Exosome immunogenicity across species allowed to verify the efficacy of good manufactory procedures-manufactured human exosomes admixed with CpG oligonucleotides in prophylactic and therapeutic settings of melanoma in HLA-A2 transgenic mice. CpG adjuvants appear to be ideal adjuvants for exosome-based cancer vaccines