1,024 research outputs found
Biodiversity and biomass of algae in the Okavango Delta (Botswana), a subtropical flood-pulsed wetland
In freshwater bodies algae provide key ecosystem services such as food and water purification. This is the first systematic assessment of biodiversity, biomass and distribution patterns of these aquatic primary producers in the Okavango Delta (Botswana), a subtropical flood-pulsed wetland in semiarid Southern Africa. This study delivers the first estimate of algal species and genera richness at the Delta scale; 496 species and 173 genera were observed in 132 samples. A new variety of desmid (Chlorophyta) was discovered, Cosmarium pseudosulcatum var. okavangicum, and species richness estimators suggest that a further few hundred unidentified species likely live in this wetland. Rare species represent 81% of species richness and 30% of total algal biovolume. Species composition is most similar within habitat types, thus varying more significantly at the Delta scale. In seasonally inundated floodplains, algal species / genera richness and diversity are significantly higher than in permanently flooded open water habitats. The annual flood pulse has historically allowed more diverse algal communities to develop and persist in these shallower and warmer environments with higher mean nutrient levels and more substrata and more heterogenous habitats for benthic taxa. These results support the Intermediate Disturbance Hypothesis, Species-Energy Theory and Habitat Heterogeneity Diversity hypotheses. Higher algal biodiversity supports higher algal biomass in the floodplains, where species form three-dimensional communities of attached and periphytic algae requiring more nutrients than phytoplankton assemblages. Multivariate analyses demonstrate that habitat type, flooding frequency and conductivity most importantly influence the relative abundance of algal species, genera and phyla in the Okavango Delta. This studyâs findings highlight how the preservation of water level fluctuations and habitat heterogeneity is crucial to maintaining biodiverse and thus resilient food webs in this unique ecosystem which faces increasing anthropogenic threats, such as global warming and upstream water abstraction plans
Endovascular Treatment of a Ruptured Pararenal Abdominal Aortic Aneurysm in a Patient With Coronavirus Disease-2019: Suggestions and Case Report
The aim of this report is to discuss emergent repair for complex aortic diseases in patients affected by novel coronavirus pneumonia (coronavirus disease-2019 [COVID-19]), describing a case of ruptured pararenal aortic aneurysm. An eighty-year-old man with COVID-19 was admitted for ruptured aneurysm of the pararenal aorta and hemorrhagic shock. Endovascular repair was chosen, and a proximal extension of the previous abdominal endograft was performed with parallel stents in the right renal artery and the superior mesenteric artery. Endovascular treatment and early anticoagulation are the key for success for vascular emergencies in patients with COVID-19, despite the risk of late endoleak
Behavioral spillovers in local public good provision: an experimental study
In a circular neighborhood, each member has a left and a right neighbor with whom(s) he interacts repeatedly. From their two separate endowment amounts individuals can contribute to each of their two structurally independent public goods, either shared only with their left, respectively right, neighbor. If most group members are discrimination averse and conditionally cooperating with their neighbors, this implies intra- as well as inter personal spillovers which link all neighbors. Investigating individual adaptations in oneâs two games with differing freeriding incentives confirms, through behavioral spillovers, that both individual contributions anchor on the local public good with the smaller free-riding incentive. Therefore asymmetry in gaining from local public goods allows to establish a higher level of voluntary cooperation
Does heterogeneity spoil the basket? The role of productivity and feedback information on public good provision
In a circular neighborhood of eight, each member contributes repeatedly to two local public goods, one with the left and one with the right neighbor. All eight two-person games provide only local feedback information and are structurally independent in spite of their overlapping player sets. Heterogeneity is induced intra-personally by asymmetric productivity in left and right games and inter-personally by two randomly selected group members who are less privileged (LP) by being either less productive or excluded from end-of-period feedback information about their payoffs and neighborsâ contributions. Although both LP-types let the neighborhood as a whole evolve less cooperatively, their spillover dynamics differ. While less productive LPs initiate âspoiling the basketâ via their low contributions, LPs with no-end-of-round information are exploited by their neighbors. Furthermore, LP-positioning, closest versus most distant, affects how the neighborhood evolves
Consumer-based actions to reduce plastic pollution in rivers: a multi-criteria decision analysis approach
The use and management of single use plastics is a major area of concern for the public, regulatory and business worlds. Focusing on the most commonly occurring consumer plastic items present in European freshwater environments, we identified and evaluated consumer-based actions with respect to their direct or indirect potential to reduce macroplastic pollution in freshwater environments. As the main end users of these items, concerned consumers are faced with a bewildering array of choices to reduce their plastics footprint, notably through recycling or using reusable items. Using a Multi-Criteria Decision Analysis approach, we explored the effectiveness of 27 plastic reduction actions with respect to their feasibility, economic impacts, environmental impacts, unintended social/environmental
impacts, potential scale of change and evidence of impact. The top ranked consumer-based actions were identified as: using wooden or reusable cutlery; switching to reusable water bottles; using wooden or reusable stirrers; using plastic free cotton-buds; and using refill detergent/ shampoo bottles. We examined the feasibility of top-ranked actions using a SWOT analysis (Strengths, Weaknesses, Opportunities and Threats) to explore the complexities inherent in their implementation for consumers, businesses, and government to reduce the presence of plastic in the environment
Diversity and evolution of a trait mediating ant-plant interactions: insights from extrafloral nectaries in Senna (Leguminosae)
Background and Aims Plants display a wide range of traits that allow them to use animals for vital tasks. To attract and reward aggressive ants that protect developing leaves and flowers from consumers, many plants bear extrafloral nectaries (EFNs). EFNs are exceptionally diverse in morphology and locations on a plant. In this study the evolution of EFN diversity is explored by focusing on the legume genus Senna, in which EFNs underwent remarkable morphological diversification and occur in over 80 % of the approx. 350 species. Methods EFN diversity in location, morphology and plant ontogeny was characterized in wild and cultivated plants, using scanning electron microscopy and microtome sectioning. From these data EFN evolution was reconstructed in a phylogenetic framework comprising 83 Senna species. Key Results Two distinct kinds of EFNs exist in two unrelated clades within Senna. âIndividualized' EFNs (iEFNs), located on the compound leaves and sometimes at the base of pedicels, display a conspicuous, gland-like nectary structure, are highly diverse in shape and characterize the species-rich EFN clade. Previously overlooked ânon-individualized' EFNs (non-iEFNs) embedded within stipules, bracts, and sepals are cryptic and may represent a new synapomorphy for clade II. Leaves bear EFNs consistently throughout plant ontogeny. In one species, however, early seedlings develop iEFNs between the first pair of leaflets, but later leaves produce them at the leaf base. This ontogenetic shift reflects our inferred diversification history of iEFN location: ancestral leaves bore EFNs between the first pair of leaflets, while leaves derived from them bore EFNs either between multiple pairs of leaflets or at the leaf base. Conclusions EFNs are more diverse than previously thought. EFN-bearing plant parts provide different opportunities for EFN presentation (i.e. location) and individualization (i.e. morphology), with implications for EFN morphological evolution, EFN-ant protective mutualisms and the evolutionary role of EFNs in plant diversificatio
The impact of integrating food supplementation, nutritional education and HAART (Highly Active Antiretroviral Therapy) on the nutritional status of patients living with HIV/AIDS in Mozambique: result from the DREAM programme
DREAM (Drug Resources Enhancement against AIDS and Malnutrition) is
a multiregional health program active in Mozambique since 2002 and provides free of charge an integrating package of care consisting of peer to peer nutritional and health education,
food supplementation, voluntary counseling and testing, immunological, virological, clinical
assessment and HAART (Highly Active AntiRetroviral Treatment). The main goals of this
paper are to describe the state of health and nutrition and the adequacy of the diet of a
sample of HIV/AIDS patients in Mozambique on HAART and not.
A single-arm retrospective cohort study was conducted. 106 HIV/AIDS adult patients (84 in
HAART), all receiving food supplementation and peer-to-peer nutritional education, were
randomly recruited in Mozambique in two public health centres where DREAM is running.
The programme is characterized by: provision of HAART, clinical and laboratory monitoring,
peer to peer health and nutritional education and food supplementation. We measured
BMI, haemoglobin, viral load, CD4 count at baseline (T0) and after at least 1 year (T1).
Dietary intake was estimated using 24h food recall and dietary diversity was assessed by
using the Dietary Diversity Score (DDS) at T1.
Overall, the patients'diet appeared to be quite balanced in nutrients. In the cohort not in
HAART the mean BMI values showed an increases but not significant (initial value: 21.9±2.9;
final value: 22.5±3.3 ) and the mean haemoglobin values (g/dl) showed a significant increases
(initial value: 10.5+ 2.1; final value: 11.5±1.7 p< 0.024) . In the cohort in HAART, both the
mean of BMI value (initial value: 20.7±3.9; final value: 21.9±3.3 p< 0.001) and of haemoglobin
(initial value: 9.9±2.2; final value: 10.8±1.7 p< 0.001) showed a higher significant increase.
The increase in BMI was statistically associated with the DDS in HAART patients.
In conclusion nutritional status improvement was observed in both cohorts. The improvement
in BMI was significant and substantially higher in HAART patients because of the impact
of HAART on nutritional status of AIDS patients. Subjects on HAART and with a DDS >
5, showed a substantial BMI gain. This association showed an additional expression of the
synergic effect of integrating food supplementation, nutritional education and HAART on
the nutritional status of African AIDS patients and also highlights the complementary role
of an adequate and diversified diet in persons living with HIV/AIDS in resources limited
settings
Competing ultrafast photoinduced electron transfer and intersystem crossing of [Re(CO)(3)(Dmp)(His124)(Trp122)]+ in Pseudomonas aeruginosa azurin:a nonadiabatic dynamics study
We present a computational study of sub-picosecond nonadiabatic dynamics in a rhenium complex coupled electronically to a tryptophan (Trp) side chain of Pseudomonas aeruginosa azurin, a prototypical protein used in the study of electron transfer in proteins. To gain a comprehensive understanding of the photoinduced processes in this system, we have carried out vertical excitation calculations at the TDDFT level of theory as well as nonadiabatic dynamics simulations using the surface hopping including arbitrary couplings (SHARC) method coupled to potential energy surfaces represented with a linear vibronic coupling model. The results show that the initial photoexcitation populates both singlet metal-to-ligand charge transfer (MLCT) and singlet charge-separated (CS) states, where in the latter an electron was transferred from the Trp amino acid to the complex. Subsequently, a complex mechanism of simultaneous intersystem crossing and electron transfer leads to the sub-picosecond population of triplet MLCT and triplet CS states. These results confirm the assignment of the sub-ps time constants of previous experimental studies and constitute the first computational evidence for the ultrafast formation of the charge-separated states in Re-sensitized azurin
Hypertension in adult Fabry's disease: is cardiotrophin-1 a diagnostic biomarker?
Background: Cardiotrophin-1 (CT-1), a cytokine produced by cardiomyocytes and non-cardiomyocytes in conditions of stress, can be used as a biomarker of left ventricular hypertrophy and dysfunction in hypertensive patients. Hypertension is one of the main adverse events in the third and last phase of Fabry's disease (FD). We measured CT-1 in order to examine its correlation with the vascular and cardiac alterations at different ages and assess its potential for use as a biomarker of hypertension in FD.
Findings: The level of CT-1 was clearly higher in hypertensive adults than in adult FD patients. FD patients show a small, non-significant decrease in plasma CT-1 with age, while in hypertensive patients CT-1 in plasma rises strongly and highly significantly with age.
Conclusions: CT-1 can be considered a good biomarker of the progression of hypertension with age, but particular care is needed when following hypertension in FD patients, since CT-1 does not correlate the same way with this disease
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