410 research outputs found
Impact of the invasive plant, Lantana camara, on bird assemblages at Malé Mahadeshwara Reserve Forest, South India
Lantana camara is an invasive species that is widespread in India. Using birds as an indicator taxon, we investigated whether Lantana invasion was correlated with changes in ecosystem health of the moist and dry deciduous forests at the Malé Madeshwara Hills, Karnataka. We studied Lantana at four densities, low, medium, and high, and a no-Lantana control. Bird species diversity, species richness, and abundance were lower at high densities of Lantana in both forest types. Evenness increased with increase in Lantana density. To better understand the observed changes in bird community composition, we segregated birds into 2 guild types: microhabitat guilds and foraging guilds. An increase in Lantana density was correlated with a decline in canopy birds (of the canopy microhabitat guilds) and insectivores (of the insectivore foraging guilds). Our results suggest that Lantana affects the structure of the bird community by decreasing diversity, and that Lantana affects certain guilds more than others
An assessment of high carbon stock and high conservation value approaches to sustainable oil palm cultivation in Gabon
Industrial-scale oil palm cultivation is rapidly expanding in Gabon, where it has the potential to drive economic growth, but also threatens forest, biodiversity and carbon resources. The Gabonese government is promoting an ambitious agricultural expansion strategy, while simultaneously committing to minimize negative environmental impacts of oil palm agriculture. This study estimates the extent and location of suitable land for oil palm cultivation in Gabon, based on an analysis of recent trends in plantation permitting. We use the resulting suitability map to evaluate two proposed approaches to minimizing negative environmental impacts: a High Carbon Stock (HCS) approach, which emphasizes forest protection and climate change mitigation, and a High Conservation Value (HCV) approach, which focuses on safeguarding biodiversity and ecosystems. We quantify the forest area, carbon stock, and biodiversity resources protected under each approach, using newly developed maps of priority species distributions and forest biomass for Gabon. We find 2.7–3.9 Mha of suitable or moderately suitable land that avoid HCS areas, 4.4 million hectares (Mha) that avoid HCV areas, and 1.2–1.7 Mha that avoid both. This suggests that Gabon's oil palm production target could likely be met without compromising important ecosystem services, if appropriate safeguards are put in place. Our analysis improves understanding of suitability for oil palm in Gabon, determines how conservation strategies align with national targets for oil palm production, and informs national land use planning
African forest elephant movements depend on time scale and individual behavior.
The critically endangered African forest elephant (Loxodonta cyclotis) plays a vital role in maintaining the structure and composition of Afrotropical forests, but basic information is lacking regarding the drivers of elephant movement and behavior at landscape scales. We use GPS location data from 96 individuals throughout Gabon to determine how five movement behaviors vary at different scales, how they are influenced by anthropogenic and environmental covariates, and to assess evidence for behavioral syndromes-elephants which share suites of similar movement traits. Elephants show some evidence of behavioral syndromes along an 'idler' to 'explorer' axis-individuals that move more have larger home ranges and engage in more 'exploratory' movements. However, within these groups, forest elephants express remarkable inter-individual variation in movement behaviours. This variation highlights that no two elephants are the same and creates challenges for practitioners aiming to design conservation initiatives
Nocardia macrotermitis sp. nov. and Nocardia aurantia sp. nov., isolated from the gut of the fungus-growing termite Macrotermes natalensis
The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20 and RB56, were determined using a polyphasic approach. Both were isolated from the fungus-farming termite Macrotermes natalensis. Results of 16S rRNA gene sequence analysis revealed that both strains are members of the genus Nocardia with the closest phylogenetic neighbours Nocardia miyunensis JCM12860 (98.9â%) and Nocardia nova DSM44481 (98.5â%) for RB20 and Nocardia takedensis DSM 44801 (98.3â%), Nocardia pseudobrasiliensis DSM 44290 (98.3â%) and Nocardia rayongensis JCM 19832 (98.2â%) for RB56. Digital DNAâDNA hybridization (DDH) between RB20 and N. miyunensis JCM12860 and N. nova DSM 44481 resulted in similarity values of 33.9 and 22.0â%, respectively. DDH between RB56 and N. takedensis DSM44801 and N. pseudobrasiliensis DSM44290 showed similarity values of 20.7 and 22.3â%, respectively. In addition, wet-lab DDH between RB56 and N. rayongensis JCM19832 resulted in 10.2â% (14.5â%) similarity. Both strains showed morphological and chemotaxonomic features typical for the genus Nocardia , such as the presence of meso-diaminopimelic acid (Apm) within the cell wall, arabinose and galactose as major sugar components within whole cell-wall hydrolysates, the presence of mycolic acids and major phospholipids (diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol), and the predominant menaquinone MK-8 (H4, Ï-cyclo). The main fatty acids for both strains were hexadecanoic acid (C), 10-methyloctadecanoic acid (10-methyl C) and cis-9-octadecenoic acid (C Ï9c). We propose two novel species within the genus Nocardia : Nocardia macrotermitis sp. nov. with the type strain RB20 (=VKM Ac-2841=NRRL B65541) and Nocardia aurantia sp. nov. with the type strain RB56 (=VKM Ac-2842=NRRL B65542)
Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon
Poaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon
Interleukin-6 receptor blockade or TNFa inhibition for reducing glycaemia in patients with RA and diabetes: post hoc analyses of three randomised, controlled trials
Background:
Diabetes is common in patients with rheumatoid arthritis (RA). Interleukin (IL)-6 is implicated in both the pathogenesis of RA and in glucose homeostasis; this post hoc analysis investigated the effects of IL-6 receptor vs. tumour necrosis factor inhibition on glycosylated haemoglobin (HbA1c) in patients with RA with or without diabetes.
Methods:
Data were from two placebo-controlled phase III studies of subcutaneous sarilumab 150/200 mg q2w +
methotrexate or conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and a phase III monotherapy study of sarilumab 200 mg q2w vs. adalimumab 40 mg q2w. Patients with diabetes were identified by medical history or use of antidiabetic medication (patients with HbA1c ? 9% were excluded from all three studies). HbA1c was measured at baseline and weeks 12/24. Safety and efficacy were assessed in RA patients with or without diabetes.
Results:
Patients with diabetes (n = 184) were older, weighed more and exhibited higher RA disease activity tan patients without diabetes (n = 1928). Regardless of diabetes status, in patients on background csDMARDs, least squares (LS) mean difference (95% CI) in change from baseline in HbA1c for sarilumab 150 mg/200 mg vs. placebo at week 24 was ? 0.28 (? 0.40, ? 0.16; nominal p < 0.0001) and ? 0.42 (? 0.54, ? 0.31; nominal p < 0.0001), respectively. Without csDMARDs, LS mean difference for sarilumab 200 mg vs. adalimumab 40mg at week 24 was ? 0.13 (? 0.22, ? 0.04; nominal p = 0.0043).
Greater reduction in HbA1c than placebo or adalimumab was observed at week 24 with sarilumab in patients with diabetes and/or baseline HbA1c ? 7%. There was no correlation between baseline/change from baseline in HbA1c and baseline/change from baseline in C-reactive protein, 28-joint Disease Activity Score, or haemoglobin, nor between HbA1c change from baseline and baseline glucocorticoid use. Medical history of diabetes or use of diabetes treatments had limited impact on safety and efficacy of sarilumab and was consistent with overall phase III findings in patients with RA.
Conclusions:
In post hoc analyses, sarilumab was associated with a greater reduction in HbA1c than csDMARDs or adalimumab, independent of sarilumab anti-inflammatory effects. Prospective studies are required to further assess these preliminary findings.
Trial registration:
ClinTrials.gov NCT01061736: date of registration February 03, 2010; ClinTrials.gov NCT01709578: date ofregistration October 18, 2012; ClinTrials.gov NCT02332590: date of registration January 07, 2015.
Arthritis Research & Therapy (2020) 22:20
Climatic and Resource Determinants of Forest Elephant Movements
As a keystone megafaunal species, African forest elephants (Loxodonta cyclotis) influence the structure and composition of tropical forests. Determining the links between food resources, environmental conditions and elephant movement behavior is crucial to understanding their habitat requirements and their effects on the ecosystem, particularly in the face of poaching and global change. We investigate whether fruit abundance or climate most strongly influence forest elephant movement behavior at the landscape scale in Gabon. Trained teams of âelephant trackersâ performed daily fruit availability and dietary composition surveys over a year within two relatively pristine and intact protected areas. With data from 100 in-depth field follows of 28 satellite-collared elephants and remotely sensed environmental layers, we use linear mixed-effects models to assess the effects of sites, seasons, focal elephant identification, elephant diet, and fruit availability on elephant movement behavior at monthly and 3-day time scales. At the month-level, rainfall, and to a lesser extent fruit availability, most strongly predicted the proportion of time elephants spent in long, directionally persistent movements. Thus, even elephants in moist tropical rainforests show seasonal behavioral phenotypes linked to rainfall. At the follow-level (2â4 day intervals), relative support for both rainfall and fruit availability decreased markedly, suggesting that at finer spatial scales forest elephants make foraging decisions largely based on other factors not directly assessed here. Focal elephant identity explained the majority of the variance in the data, and there was strong support for interindividual variation in behavioral responses to rainfall. Taken together, this highlights the importance of approaches which follow individuals through space and time. The links between climate, resource availability and movement behavior provide important insights into the behavioral ecology of forest elephants that can contribute to understanding their role as seed dispersers, improving management of populations, and informing development of solutions to human-elephant conflict
Distinct Community-Wide Responses to Forecasted Climate Change in Afrotropical Forests
More refined knowledge of how tropical forests respond to changes in the abiotic environment is necessary to mitigate climate change, maintain biodiversity, and preserve ecosystem services. To evaluate the unique response of diverse Afrotropical forest communities to disturbances in the abiotic environment, we employ country-wide tree species inventories, remotely sensed climate data, and future climate predictions collected from 104 1-ha plots in the central African country of Gabon. We predict a 3â8% decrease in Afrotropical forest species richness by the end of the century, in contrast to the 30â50% loss of plant diversity predicted to occur with equivalent warming in the Neotropics. This work reveals that forecasts of community species composition are not generalizable across regions, and more representative studies are needed in understudied diverse biomes. This study serves as an important counterpoint to work done in the Neotropics by providing contrasting predictions for Afrotropical forests with substantially different ecological, evolutionary, and anthropogenic histories
Exploring the relation between remotely sensed vertical canopy structure and tree species diversity in Gabon
Mapping tree species diversity is increasingly important in the face of environmental change and biodiversity conservation. We explore a potential way of mapping this diversity by relating forest structure to tree species diversity in Gabon. First, we test the relation between canopy height, as a proxy for niche volume, and tree species diversity. Then, we test the relation between vertical canopy structure, as a proxy for vertical niche occupation, and tree species diversity. We use large footprint full-waveform airborne lidar data collected across four study sites in Gabon (LopĂ©, MabouniĂ©, Mondah, and Rabi) in combination with in situ estimates of species richness (S) and Shannon diversity (HâČ). Linear models using canopy height explained 44% and 43% of the variation in S and HâČ at the 0.25 ha resolution. Linear models using canopy height and the plant area volume density profile explained 71% of this variation. We demonstrate applications of these models by mapping S and HâČ in Mondah using a simulated GEDI-TanDEM-X fusion height product, across the four sites using wall-to-wall airborne lidar data products, and across and between the study sites using ICESat lidar waveforms. The modeling results are encouraging in the context of developing pan-tropical structure diversity models applicable to data from current and upcoming spaceborne remote sensing missions
Superposition of macroscopic numbers of atoms and molecules
We theoretically examine photoassociation of a non-ideal Bose-Einstein
condensate, focusing on evidence for a macroscopic superposition of atoms and
molecules. This problem raises an interest because, rather than two states of a
given object, an atom-molecule system is a seemingly impossible macroscopic
superposition of different objects. Nevertheless, photoassociation enables
coherent intraparticle conversion, and we thereby propose a viable scheme for
creating a superposition of a macroscopic number of atoms with a macroscopic
number of molecules.Comment: 4 pages, 2 figs, to appear in Phys. Rev. Let
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