Does a Carbonatite Deposit Influence Its Surrounding Ecosystem?

Carbonatites are unusual alkaline rocks with diverse compositions. Although previous work has characterized the effects these rocks have on soils and plants, little is known about their impacts on local ecosystems. Using a deposit within the Great Lakes–St. Lawrence forest in northern Ontario, Canada, we investigated the effect of a carbonatite on soil chemistry and on the structure of plant and soil microbial communities. This was done using a vegetation survey conducted above and around the deposit, with corresponding soil samples collected for determining soil nutrient composition and for assessing microbial community structure using 16S/ITS Illumina Mi-Seq sequencing. In some soils above the deposit a soil chemical signature of the carbonatite was found, with the most important effect being an increase in soil pH compared with the non-deposit soils. Both plants and microorganisms responded to the altered soil chemistry: the plant communities present in carbonatite-impacted soils were dominated by ruderal species, and although differences in microbial communities across the surveyed areas were not obvious, the abundances of specific bacteria and fungi were reduced in response to the carbonatite. Overall, the deposit seems to have created microenvironments of relatively basic soil in an otherwise acidic forest soil. This study demonstrates for the first time how carbonatites can alter ecosystems in situ

Social and cultural factors affecting rates of regular retreatment of mosquito nets with insecticide in Bagamoyo District, Tanzania

Insecticide-treated mosquito nets have an impact on mortality and morbidity in young children under controlled conditions. When integrated into larger control programs, there is the danger that rates of regular retreatment of the nets with insecticide will drop, greatly limiting their effectiveness as a public health intervention. In Bagamoyo District, Tanzania, rates of retreatment dropped significantly when payment for the insecticide was introduced. A series of neighbourhood (hamlet) meetings were held in all study villages to discuss people\u27s concerns about the insecticide and ways to increase rates of retreatment. Although changes were made in the procedure for retreatment, rates of retreatment remained lower than expected and showed marked variation within as well as between villages. We then conducted unstructured key informant interviews as well as informal discussions in a village with strong variation between different sectors of the village in rates of retreatment. While logistical problems were most frequently cited as reasons not to bring nets for retreatment, political and social divisions within the community provided a better explanation. This is borne out by the low response to rearrangements in logistics which made retreating the nets significantly easier for households, and the higher response when changes were made in the channels of communication as well as the logistic features. It is clearly more difficult for villagers to appreciate the benefits of the insecticide than those of the nets. Great emphasis needs to be placed on the insecticide and its beneficial effects from the outset for any large-scale programme to be sustainable

Vastus lateralis/vastus medialis cross-sectional area ratio impacts presence and degree of knee joint abnormalities and cartilage T2 determined with 3T MRI – an analysis from the incidence cohort of the Osteoarthritis Initiative

SummaryObjectiveTo study the role of vastus lateralis/vastus medialis cross-sectional area CSA ratio (VL/VM CSA ratio) in preclinical knee osteoarthritis (OA) using magnetic resonance imaging (MRI)-based cartilage T2 mapping technique and morphological analysis at 3.0T in non-symptomatic, middle-aged subjects.Material and methods174 non-symptomatic individuals aged 45–55 years with OA risk factors were selected from the Osteoarthritis Initiative (OAI) incidence cohort. OA-related knee abnormalities were analyzed using the whole-organ magnetic resonance imaging score (WORMS). Knee cartilage T2 maps were generated using sagittal 2D multi-echo spin-echo images of the right knee. CSA of thigh muscles was measured using axial T1W images of the right mid thigh. Spline-based segmentation of cartilage and muscles was performed on a SUN/SPARC workstation. Muscle measurements were normalized to body size using body surface area (BSA). Statistical significance was determined using Student’s t-test, Pearson correlation test, and multiple regression models. To correct for multiple testing, Bonferroni adjustments were applied across all tests within each of the primary results tables (Tables III–VII).ResultsHigher T2 values were associated with increased prevalence and severity of cartilage degeneration. In our study, male and female subjects with higher VL/VM CSA ratio demonstrated significantly lower mean cartilage T2 values (all compartments combined) (mean 44.10 vs 45.17, P=0.0017), and significantly lower WORMS scores (mean 14.12 vs 18.68, P=0.0316). Regression analyses of combined mean cartilage T2 using VL/VM CSA ratio as a continuous predictor showed a significant curvilinear relationship between these two variables (P=0.0082).ConclusionOur results suggested that higher VL/VM CSA ratio is associated with lower T2 values and decreased presence and severity of OA-related morphological changes. Additional studies will be needed to determine causality

Severe radiographic knee osteoarthritis – does Kellgren and Lawrence grade 4 represent end stage disease? – the MOST study

SummaryObjectiveTo determine what MRI-detectable osteoarthritis features that are not visualized on radiography demonstrate progression longitudinally in Kellgren and Lawrence (KL) grade 4 knees.MethodsWe studied subjects from the Multicenter Osteoarthritis Study who had KL grade 4 knees at baseline and had baseline and 30-month MRI. Cartilage damage, bone marrow lesions (BMLs), meniscal damage, synovitis (signal changes in Hoffa fat pad), and effusion (fluid equivalent signal in the joint cavity) were semiquantitatively scored using the Whole Organ MRI Score (WORMS) system in five subregions of the medial and lateral tibiofemoral (TF) compartments. Analysis was performed for the compartment showing bone-on-bone appearance (“index”) on radiograph and also for the other TF compartment of the same knee. Synovitis and effusion were assessed for the whole knee. Changes in scores at follow-up were noted for each feature. For cartilage and BML, within-grade changes were also recorded.Results140 subjects (164 knees) were included (50% women, mean age 66.0 ± 8.6 years, mean BMI 30.4 ± 5.1 kg/m2). Longitudinally, 51 index compartments (34%) showed an increase in the sum of cartilage scores from all subregions. In the other compartment, 25% showed an increase in the sum score for cartilage damage. For BMLs in the index compartment, 50 knees (33%) showed an increase in maximum score and 32 (21%) showed a decrease. Meniscal status mostly remained stable. Effusion worsened in 36 knees (25%) and improved in 13 knees (9%). Synovitis worsened in 14 knees (10%) and improved in six knees (4%).ConclusionIn KL grade 4 knees, MRI-detected cartilage loss and fluctuation of BMLs, effusion, and synovitis occurred frequently over a 30-month period

Synchronous counting and computational algorithm design

Consider a complete communication network on n nodes, each of which is a state machine with s states. In synchronous 2-counting, the nodes receive a common clock pulse and they have to agree on which pulses are “odd” and which are “even”. We require that the solution is self-stabilising (reaching the correct operation from any initial state) and it tolerates f Byzantine failures (nodes that send arbitrary misinformation). Prior algorithms are expensive to implement in hardware: they require a source of random bits or a large number of states s. We use computational techniques to construct very compact deterministic algorithms for the first non-trivial case of f = 1. While no algorithm exists for n < 4, we show that as few as 3 states are sufficient for all values n ≥ 4. We prove that the problem cannot be solved with only 2 states for n = 4, but there is a 2-state solution for all values n ≥ 6.Peer reviewe