Tromsø research foundation

Multiple propagation modes between different bistatic radar links were measured during the operations of a very high frequency (VHF) 32.55 MHz radar system in northern Norway. The Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) Norway system detected meteor trails, direct transmitter to receiver signal propagation, over-the-horizon signal propagation from the SIMONe Germany system, ground and/or sea scatter, and ionospheric scatter on 27 August 2021 between 16:30–20:00 UT. These simultaneous detections were during an active ionospheric period with multiple occurrences of energetic charged particle precipitation. The SIMONe systems used continuous-wave (CW) pseudo-random phase modulated transmit signals and interferometry to make it possible to isolate each of these propagation modes and examine their characteristics. Different multistatic links at three receiver locations were analyzed, providing multistatic measurements of the regions with spatial and temporal resolutions on the order of 1.5 km and 2 s. The analysis techniques are described, with characteristics of the radar signal presented for each propagation mode and multistatic link. This study serves to highlight the capabilities of the SIMONe Norway system to research multiple aspects of ionospheric phenomena, specifically in the lower thermosphere-mesosphere boundary region.

Abstract Alpine areas are well known biodiversity hotspots, but their future may be threatened by expanding forest and changing human land use. Here, we reconstructed past vegetation, climate, and livestock over the past ~ 12,000 years from Lake Sulsseewli (European Alps), based on sedimentary ancient DNA, pollen, spores, chironomids, and microcharcoal. We assembled a highly-complete local DNA reference library (PhyloAlps, 3,923 plant species), and used this to obtain an exceptionally rich sedaDNA record of 366 plant taxa. The vegetation mainly responded to temperature during the first half of the Holocene, while human activity drove changes from 6 ka onwards. Land-use shifted from episodic grazing (Neolithic, Bronze Age) to agropastoral intensification (Medieval Age). This prompted a coexistence of species typically found at different elevational belts, thereby increasing plant richness to levels that characterise present-day alpine diversity. Our results indicate that traditional agropastoral activities should be maintained to prevent reforestation and preserve alpine plant biodiversity.

Traditionally, studies of historical mortality have focused on the national, regional, or local levels. Currently, the creation of individual level databases has made it possible to study mortality at the individual and family levels, also following people over generations. However, this research rarely considered non-family relations; at the same time, rapid urbanisation during the late nineteenth century severed many family ties and hindered the transmission of traditional models for demographic behaviour. Thus, the role of non-family factors increased, the main of which was the church parish, which since the end of the nineteenth century gradually transformed into a neighborhood community — the prototype of the urban microdistrict. This research aims to study the mortality of the adult population of Ekaterinburg during the decades around 1900, differentiating between the parishes of the Russian Orthodox Church. The sources consist of official statistics and the Ural Population Project database, which was created based on the metric (church) books. The authors reconstruct the full development of mortality for each parish and for Ekaterinburg as a whole; map the structure of mortality, calculate the average age at death, as well as analyse the causes of death and its seasonality. As a result, it may be concluded that each of the five Orthodox parishes indeed had a certain demographic specificity. Mortality was influenced by the economic profile of the area and the trend of urban development, where the location of social facilities on the territory of each parish was of great importance.

Identification of the cognitive mechanisms behind gait changes in aging is a prime endeavor in gerontology and geriatrics. For this reason, we have implemented a new dual-task paradigm where an auditory attentional task is performed during over-ground walking. Dichotic listening assesses spontaneous attention and voluntary attention directed to right and left-ear. The uniqueness of dichotic listening relies on its requirements that vary in difficulty and recruitment of resources from whole brain to one brain hemisphere. When used in dual-tasking, asymmetric effects on certain gait parameters have been reported. The present study aims to acquire a more global understanding on how dichotic listening affects gait domains. Specifically, we aimed to understand how spontaneous vs lateralized auditory attention altered the Principal Component Analysis (PCA) structure of gait in healthy older adults. Seventy-eight healthy older adults (mean age: 71.1years; 44 women and 34 men) underwent the Bergen dichotic listening test while walking. As this study only focuses on the effects of the cognitive task on gait, only dual-task costs for gait were calculated and entered into the PCA analyses. We explored the PCA structure for the effects on bilateral gait parameters (i.e., both limbs together) as well as on lateralized gait parameters (i.e, separate parameters by limb). We first established gait domains during single-task walking. Then, dual-task cost scores for gait were entered in a series of PCAs. Results from the PCAs for bilateral gait parameters showed limited alterations on gait structure. In contrast, PCAs for lateralized data demonstrated modifications of the gait structure during dichotic listening. The PCAs corresponding for all dichotic listening conditions showed different factor solutions ranging between 4 and 6 factors that explained between 73.8% to 80% of the total variance. As a whole, all conditions had an impact on "pace", "pace variability" and "base of support variability" domains. In the spontaneous attention condition, a six-factor solution explaining 78.3% of the variance showed asymmetrical disruptions on the PCA structure. When attention was focused to right-ear, a five-factor solution explaining 89% of the variance and similar to baseline was found. When attention was directed to left-ear, a four-factor solution explaining 73.8% of the variance was found with symmetrical impact on all factors. These findings demonstrate for the first time that specific facets of attentional control affects gait domains both symmetrically and asymmetrically in healthy older adults.

The syntheses of metallo-β-lactamase inhibitors comprising chelating moieties, with varying zinc affinities, and peptides partly inspired from bacterial peptide sequences, have been undertaken. The zinc chelator strength was varied using the following chelators, arranged in order of ascending binding affinity: dipicolylamine (DPA, tridentate), dipicolyl-1,2,3-triazolylmethylamine (DPTA, tetradentate) dipicolyl ethylenediamine (DPED, tetradentate) and trispicolyl ethylenediamine (TPED, pentadentate). The chosen peptides were mainly based on the known sequence of the C-terminus of the bacterial peptidoglycan precursors. Biological evaluation on clinical bacterial isolates, harbouring either the NDM-1 or VIM-2 metallo-β-lactamase, showed a clear relationship between the zinc chelator strength and restoration of meropenem activity. However, evaluation of toxicity on different cancer cell lines demonstrated a similar trend, and thus inclusion of the bacterial peptides did possess rather high toxicity towards eukaryotic cells.

In this work, we study the surface energy of monolayer, bilayer and multilayer graphene coatings, produced through exfoliation of natural graphite flakes and chemical vapor deposition. We employ bimodal atomic force microscopy and micro-Raman spectroscopy for high spatial resolution and large area scanning of force of adhesion on the regions of the graphene/SiO2 surface with different graphene layers. Our measurements show that the interface conditions between graphene and SiO2 dominate the experimentally observed graphene surface energy. This finding sheds new light on the controversy surrounding graphene transparency studies. By separating the surface energy into polar and non-polar interactions, our findings suggest that monolayer graphene is nearly van der Waals opaque but partially transparent (near 60%) to polar interactions, which is further supported by characterizing graphene on the copper surface and two levels of density functional theory simulation. In addition to providing quantitative insight into the surface interactions of complicated graphene coatings, this work demonstrates a new route to nondestructively monitor the interface between graphene and coated substrates.

Rates of intersystem crossing (kISC) of two platinum(ii) complexes containing acetylacetonate (acac) and extended cyclometalated ppy (Hppy = 2-phenylpyridine) (1) and thpy (Hthpy = 2-(2' thienyl)pyridine) (2) ligands are calculated using the Condon approximation to the Golden Rule and employing the second-order cumulant expansion method. The emission wavelengths obtained at the RI-CC2 level for the lowest excited singlet (S1) and triplet (T1) states of the two complexes are well in agreement with the experimental results. Our analysis based on kISC evinces that the major pathway involved with the phosphorescence process in complex 1 arises from the S1 → T2 intersystem crossing while the S1 → T1 intersystem crossing is the key step towards the commencement of dual emission in complex 2. Furthermore, it is found that the different pathways are mostly guided by two factors namely, the energy gap and the spin-orbit interaction between the concerned states. Interestingly, the calculated kISC for complex 1 is found to be 107 times larger than that of complex 2, which suggests a rapid depletion of the S1 state population vis-à-vis radiative emission only by phosphorescence from the internally converted lowest excited triplet state while for complex 2, the relatively lower kISC is attributed to the dual emission from this complex.