Aim
Species differ in their degree of specialization when interacting with other species, with significant consequences for the function and robustness of ecosystems. In order to better estimate such ...consequences, we need to improve our understanding of the spatial patterns and drivers of specialization in interaction networks.
Methods
Here, we used the extensive environmental gradient of Mt. Kilimanjaro (Tanzania, East Africa) to study patterns and drivers of specialization, and robustness of plant–pollinator interactions against simulated species extinction with standardized sampling methods. We studied specialization, network robustness and other network indices of 67 quantitative plant–pollinator networks consisting of 268 observational hours and 4,380 plant–pollinator interactions along a 3.4 km elevational gradient. Using path analysis, we tested whether resource availability, pollinator richness, visitation rates, temperature, and/or area explain average specialization in pollinator communities. We further linked pollinator specialization to different pollinator taxa, and species traits, that is, proboscis length, body size, and species elevational ranges.
Results
We found that specialization decreased with increasing elevation at different levels of biological organization. Among all variables, mean annual temperature was the best predictor of average specialization in pollinator communities. Specialization differed between pollinator taxa, but was not related to pollinator traits. Network robustness against simulated species extinctions of both plants and pollinators was lowest in the most specialized interaction networks, that is, in the lowlands.
Conclusions
Our study uncovers patterns in plant–pollinator specialization along elevational gradients. Mean annual temperature was closely linked to pollinator specialization. Energetic constraints, caused by short activity timeframes in cold highlands, may force ectothermic species to broaden their dietary spectrum. Alternatively or in addition, accelerated evolutionary rates might facilitate the establishment of specialization under warm climates. Despite the mechanisms behind the patterns have yet to be fully resolved, our data suggest that temperature shifts in the course of climate change may destabilize pollination networks by affecting network architecture.
We studied specialization patterns in plant–pollinator interactions along a 3.4 km elevational gradient on Mt. Kilimanjaro (Tanzania) and demonstrated that specialization decreased with elevation across networks, communities, and pollinator species. Temperature predicted the degree of specialization better than pollinator richness, resource availability, area, or pollinator traits. Despite the mechanisms behind the patterns have yet to be fully resolved, we conclude that temperature shifts in the course of climate change may destabilize pollination networks by affecting network architecture.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We reviewed 122 peer-reviewed studies on the effects of organic toxicants and heavy metals on three fundamental ecosystem functions in freshwater ecosystems, i.e. leaf litter breakdown, primary ...production and community respiration. From each study meeting the inclusion criteria, the concentration resulting in a reduction of at least 20% in an ecosystem function was standardized based on median effect concentrations of standard test organisms (i.e. algae and daphnids). For pesticides, more than one third of observations indicated reductions in ecosystem functions at concentrations that are assumed being protective in regulation. Moreover, the reduction in leaf litter breakdown was more pronounced in the presence of invertebrate decomposers compared to studies where only microorganisms were involved in this function. High variability within and between studies hampered the derivation of a concentration–effect relationship. Hence, if ecosystem functions are to be included as protection goal in chemical risk assessment standardized methods are required.
•Quantitative review of 122 studies on effects of toxicants on ecosystem functions.•Variation between studies hampered derivation of concentration–effect relationships.•Adverse effects of pesticide were observed below thresholds corresponding to regulation.•Effects on leaf breakdown were greater when invertebrates were involved.
Concentrations assumed as protective in chemical regulation cause adverse effects in three fundamental ecosystem functions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The formation of branched lariat RNA is an evolutionarily conserved feature of splicing reactions for both group II and spliceosomal introns. The lariat is important for the fidelity of 5' ...splice-site selection and consists of a 2'-5' phosphodiester bond between a bulged adenosine and the 5' end of the intron. To gain insight into this ubiquitous intramolecular linkage, we determined the crystal structure of a eukaryotic group IIB intron in the lariat form at 3.7 Å. This revealed that two tandem tetraloop-receptor interactions, η-η' and π-π', place domain VI in the core to position the lariat bond in the post-catalytic state. On the basis of structural and biochemical data, we propose that π-π' is a dynamic interaction that mediates the transition between the two steps of splicing, with η-η' serving an ancillary role. The structure also reveals a four-magnesium-ion cluster involved in both catalysis and positioning of the 5' end. Given the evolutionary relationship between group II and nuclear introns, it is likely that this active site configuration exists in the spliceosome as well.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose We determined the efficacy and safety of pelvic floor myofascial physical therapy compared to global therapeutic massage in women with newly symptomatic interstitial cystitis/painful bladder ...syndrome. Materials and Methods A randomized controlled trial of 10 scheduled treatments of myofascial physical therapy vs global therapeutic massage was performed at 11 clinical centers in North America. We recruited women with interstitial cystitis/painful bladder syndrome with demonstrable pelvic floor tenderness on physical examination and a limitation of no more than 3 years' symptom duration. The primary outcome was the proportion of responders defined as moderately improved or markedly improved in overall symptoms compared to baseline on a 7-point global response assessment scale. Secondary outcomes included ratings for pain, urgency and frequency, the O'Leary-Sant IC Symptom and Problem Index, and reports of adverse events. We compared response rates between treatment arms using the exact conditional version of the Mantel-Haenszel test to control for clustering by clinical center. For secondary efficacy outcomes cross-sectional descriptive statistics and changes from baseline were calculated. Results A total of 81 women randomized to the 2 treatment groups had similar symptoms at baseline. The global response assessment response rate was 26% in the global therapeutic massage group and 59% in the myofascial physical therapy group (p = 0.0012). Pain, urgency and frequency ratings, and O'Leary-Sant IC Symptom and Problem Index decreased in both groups during followup, and were not significantly different between the groups. Pain was the most common adverse event, occurring at similar rates in both groups. No serious adverse events were reported. Conclusions A significantly higher proportion of women with interstitial cystitis/painful bladder syndrome responded to treatment with myofascial physical therapy than to global therapeutic massage. Myofascial physical therapy may be a beneficial therapy in women with this syndrome.
If one nondescript object's volume is twice that of another, is it necessarily twice as heavy? As larger objects are typically heavier than smaller ones, one might assume humans use such heuristics ...in preparing to lift novel objects if other informative cues (e.g., material, previous lifts) are unavailable. However, it is also known that humans are sensitive to statistical properties of our environments, and that such sensitivity can bias perception. Here we asked whether statistical regularities in properties of liftable, everyday objects would bias human observers' predictions about objects' weight relationships. We developed state-of-the-art computer vision techniques to precisely measure the volume of everyday objects, and also measured their weight. We discovered that for liftable man-made objects, "twice as large" doesn't mean "twice as heavy": Smaller objects are typically denser, following a power function of volume. Interestingly, this "smaller is denser" relationship does not hold for natural or unliftable objects, suggesting some ideal density range for objects designed to be lifted. We then asked human observers to predict weight relationships between novel objects without lifting them; crucially, these weight predictions quantitatively match typical weight relationships shown by similarly-sized objects in everyday environments. These results indicate that the human brain represents the statistics of everyday objects and that this representation can be quantitatively abstracted and applied to novel objects. Finally, that the brain possesses and can use precise knowledge of the nonlinear association between size and weight carries important implications for implementation of forward models of motor control in artificial systems.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Species' functional traits set the blueprint for pair-wise interactions in ecological networks. Yet, it is unknown to what extent the functional diversity of plant and animal communities controls ...network assembly along environmental gradients in real-world ecosystems. Here we address this question with a unique dataset of mutualistic bird-fruit, bird-flower and insect-flower interaction networks and associated functional traits of 200 plant and 282 animal species sampled along broad climate and land-use gradients on Mt. Kilimanjaro. We show that plant functional diversity is mainly limited by precipitation, while animal functional diversity is primarily limited by temperature. Furthermore, shifts in plant and animal functional diversity along the elevational gradient control the niche breadth and partitioning of the respective other trophic level. These findings reveal that climatic constraints on the functional diversity of either plants or animals determine the relative importance of bottom-up and top-down control in plant-animal interaction networks.
This paper presents a method for obtaining time dependent back face deformation (BFD) data for body armor during ballistic impact using a clear ballistics gelatin backing and high-speed cameras to ...capture the deformation profile. Using this method, baseline fabric characterization data was obtained for samples comprised of varying layers of 467 g/m2 Kevlar K29 fabric impacted with 8.24 g steel ball projectile and backed with NATO standard 20% clear ballistics gelatin. For these tests, deformation depths were seen to increase with increasing impact energy and decreasing total areal density. A limited study of the various test parameters was performed by testing one additional fabric, projectile, and ballistics gelatin. From these comparisons, it was observed that 122 g/m2 Kevlar KM2+ fabric performs better per weight than 467 g/m2 Kevlar K29 fabric in terms of BFD, 9 mm FMJ projectiles produce deeper BFDs than 12.7 mm steel ball projectiles, and backing a sample with FBI standard 10% ballistics gel increases the BFD considerably over NATO standard 20% ballistics gel.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The lumped‐structure approach for condensing organic chemical mechanisms is attractive, since it yields fewer species and reactions and reduces computational costs. This paper leads through the ...development of a new lumped‐structure mechanism, largely based on the widely used Carbon Bond Mechanism (CBM‐IV) developed by Gery et al. 1989. The new mechanism called CBM‐Z extends the original framework to function properly at larger spatial and longer timescales. The major modifications in the mechanism include revised inorganic chemistry; explicit treatment of the lesser reactive paraffins, methane and ethane; revised parameterizations of the reactive paraffin, olefin, and aromatic reactions; inclusion of alkyl and acyl peroxy radical interactions and their reactions with NO3; inclusion of organic nitrates and hydroperoxides; and refined isoprene chemistry based on the condensed one‐product mechanism of Carter 1996. CBM‐Z was successfully evaluated along with the CBM‐IV, a partially revised CBM‐IV, and a revised Regional Acid Deposition Model (RADM2) mechanism Stockwell et al., 1990; Kirchner and Stockwell, 1996 using the low NOx and volatile organic compound concentration smog chamber experiments of Simonaitis et al. 1997. Box model versions of the four mechanisms were also evaluated under a variety of hypothetical urban and rural scenarios for a period of 30 days. Results from CBM‐Z and revised RADM2 were found to be within ±20% of each other, while CBM‐IV and revised CBM‐IV results deviated significantly by up to 50–95%. Sensitivity tests were performed to elucidate the effects of some of the new features added in CBM‐Z. Relative computational memory and time requirements of these mechanisms are also discussed.
Urogenital schistosomiasis (UGS) caused by Schistosoma haematobium is endemic in the South West Region of Cameroon. An understanding of the abundance and distribution of the Bulinus snail, ...intermediate host can inform strategic snail control programmes at a local scale. This study investigated seasonal dynamics and environmental factors influencing occurrence and abundance of freshwater snail intermediate hosts in Tiko, a semi-urban endemic focus in the Mount Cameroon area. A longitudinal malacological field survey was conducted between December 2019 and December 2020 in the Tiko municipality. Snails were collected for one year monthly at 12 different human water contact sites along a stretch of the Ndongo stream using a standardized sampling technique. Freshwater snails were identified using shell morphological features. In addition, water temperature, pH, electrical conductivity, total dissolved solutes, salinity, water depth, width and flow velocity were measured, and vegetation cover as well as substrate type were determined. Bayesian regression models were used to identify the main environmental factors affecting the occurrence and abundance of Bulinus intermediate host. In total, 2129 fresh water snails were collected during the study period. Physa (51.4%) was the most abundant genus followed by Melanoides (28.6%) then, Bulinus (15.5%), Lymnaea (4.2%), Indoplanorbis (0.2%) and Potadoma (0.1%). Seasonality in abundance was significant in Bulinus sp as well as other genera, with greater numbers in the dry season (peaks between December and February). Water temperature, a rocky or sandy substrate type associated positively with Bulinus sp, meanwhile a higher water flow rate and medium vegetation negatively influenced the snail intermediate host population. These findings underscore the importance of timing behavioural and snail control interventions against schistosomiasis as well as increase vigilance of other trematode diseases in the study area. The continuous spread of planorbid snail hosts is a major concern.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Fiber Bragg grating (FBG) sensors are excellent transducers for collecting ultrasonic wave signals for structural health monitoring (SHM). Typically, FBG sensors are directly bonded to the surface of ...a structure to detect signals. Unfortunately, demodulating relevant information from the collected signal demands a high signal-to-noise ratio because the structural ultrasonic waves have low amplitudes. Our previous experimental work demonstrated that the optical fiber could be bonded at a distance away from the FBG location, referred to here as remote bonding. This remote bonding technique increased the output signal amplitude compared to the direct bonding case, however the mechanism causing the increase was not explored. In this work, we simulate the previous experimental work through transient analysis based on the finite element method, and the output FBG response is calculated through the transfer matrix method. The model is first constructed without an adhesive to assume an ideal bonding condition, investigating the difference in excitation signal coherence along the FBG length between the two bonding configurations. A second model is constructed with an adhesive to investigate the effect of the presence of the adhesive around the FBG. The results demonstrate that the amplitude increase is originated not from the excitation signal coherence, but from the shear lag effect which causes immature signal amplitude development in the direct bonding case compared to the remote bonding case. The results also indicate that depending on the adhesive properties the surface-bonded optical fiber manifests varying resonant frequency, therefore resulting in a peak amplitude response when the input excitation frequency is matched. This work provides beneficial reference for selecting adhesive and calibrating sensing system for maximum ultrasonic detection sensitivity using the FBG sensor.
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