459 research outputs found
The effects of recruitment to direct predator cues on predator responses in meerkats
Behavioral responses of animals to direct predator cues (DPCs; e.g., urine) are common and may improve their survival. We investigated wild meerkat (Suricata suricatta) responses to DPCs by taking an experimental approach. When meerkats encounter a DPC they often recruit group members by emitting a call type, which causes the group members to interrupt foraging and approach the caller. The aim of this study was to identify the qualities of olfactory predator cues, which affect the strength of response by meerkats, and determine the benefits of responses to such cues. Experimental exposure to dog (Canis lupus) urine as a DPC revealed that the recruited individuals increased vigilance to fresh urine in comparison to older urine, whereas a higher quantity of urine did not induce such an effect. Both freshness and higher quantities increased the proportion of group members recruited. These results indicate that recruitment might play a crucial role in correctly assessing the current level of danger and that recruiting might facilitate group decision making. To test the prediction that the reaction to a DPC enhances early predator response, we presented a DPC of a predator and a control cue of a herbivore, and each time simultaneously moved a full-mounted caracal (Caracal caracal) in the vicinity of the group. Meerkats responded earlier to the caracal when the DPC was presented, indicating that the response to a DPC facilitates predator response and that they use information from the cue that reliably reflects the risk in the current momen
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Nd:YAG laser welding experiments
Laser-beam/plume interaction experiments were conducted with a pulsed Nd:YAG laser. A high speed camera was used to study plume growth phenomena and to determine maximum plume velocities. Tests were done on four different metals: Aluminum 1100, Molybdenum, Nickel 200, and Stainless Steel 304. Previous laser welding experiments have indicated that the vapor plume ejected from the irradiated base material significantly attenuates the laser beam energy for Nickel 200 and Stainless Steel 304. To substantiate this observation, the plume was subjected to a cross flow of argon gas. Metallurgical studies showed a significant increase in weld penetration for all materials except for Aluminum. These experiments also indicated that the plume ejects normal to the base material. Thus, the specimen was tilted at different angles in an attempt to reduce laser beam attenuation. Results showed no significant increase in weld depth when the tilt angle was increased. Mass loss measurements were also performed and the experimental data were an order-of-magnitude less than those predicted by a numerical laser welding code
Massive Stars: Their Environment and Formation
Cloud environment is thought to play a critical role in determining the
mechanism of formation of massive stars. In this contribution we review the
physical characteristics of the environment around recently formed massive
stars. Particular emphasis is given to recent high angular resolution
observations which have improved our knowledge of the physical conditions and
kinematics of compact regions of ionized gas and of dense and hot molecular
cores associated with luminous O and B stars. We will show that this large body
of data, gathered during the last decade, has allowed significant progress in
the understanding of the physical processes that take place during the
formation and early evolution of massive stars.Comment: Pub. Astron. Soc. of Pacific (Invited Review), 95 pages (Latex), 5
pages (tables, Latex), 11 postscript or gif figure
Methane budget estimates in Finland from the CarbonTracker Europe-CH4 data assimilation system
This is the final version. Available from the publisher via the DOI in this record.We estimated the CH4 budget in Finland for 2004â2014 using the CTE-CH4 data assimilation system with an extended atmospheric CH4 observation network of seven sites from Finland to surrounding regions (HyytiĂ€lĂ€, KjĂžlnes, Kumpula, Pallas, Puijo, SodankylĂ€, and Utö). The estimated average annual total emission for Finland is 0.6 ± 0.5 Tg CH4 yrâ1. Sensitivity experiments show that the posterior biospheric emission estimates for Finland are between 0.3 and 0.9 Tg CH4 yrâ1, which lies between the LPX-Bern-DYPTOP (0.2 Tg CH4 yrâ1) and LPJG-WHyMe (2.2 Tg CH4 yrâ1) process-based model estimates. For anthropogenic emissions, we found that the EDGAR v4.2 FT2010 inventory (0.4 Tg CH4 yrâ1) is likely to overestimate emissions in southernmost Finland, but the extent of overestimation and possible relocation of emissions are difficult to derive from the current observation network. The posterior emission estimates were especially reliant on prior information in central Finland. However, based on analysis of posterior atmospheric CH4, we found that the anthropogenic emission distribution based on a national inventory is more reliable than the one based on EDGAR v4.2 FT2010. The contribution of total emissions in Finland to global total emissions is only about 0.13%, and the derived total emissions in Finland showed no trend during 2004â2014. The model using optimized emissions was able to reproduce observed atmospheric CH4 at the sites in Finland and surrounding regions fairly well (correlation > 0.75, bias < ± ppb), supporting adequacy of the observations to be used in atmospheric inversion studies. In addition to global budget estimates, we found that CTE-CH4 is also applicable for regional budget estimates, where small scale (1x1 in this case) optimization is possible with a dense observation network.Natural Environment Research Council (NERC)NordFrosk Nordic Centre of ExcellenceAcademy of FinlandEuropean Research Council (ERC)Swiss National Science Foundation (SNSF)Swedish Research Counci
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Antibiotic knowledge, attitudes, and practices: new insights from cross-sectional rural health behaviour surveys in low- and middle-income South-East Asia
Introduction: Low- and middle-income countries (LMICs) are crucial in the global response to
antimicrobial resistance (AMR), but diverse health systems, healthcare practices, and cultural
conceptions of medicine can complicate global education and awareness-raising campaigns. Social
research can help understand LMIC contexts but remains underrepresented in AMR research.
Objective: To (1) describe antibiotic-related knowledge, attitudes, and practices of the general
population in two LMICs and to (2) assess the role of antibiotic-related knowledge and attitudes on
antibiotic access from different types of healthcare providers.
Design: Observational study: cross-sectional rural health behaviour survey, representative on the
population level.
Setting: General rural population in Chiang Rai (Thailand) and Salavan (Lao PDR), surveyed between
November 2017 and May 2018.
Participants: 2141 adult members (â„18 years) of the general rural population, representing 712,000
villagers.
Outcome measures: Antibiotic-related knowledge, attitudes, and practices across sites and healthcare
access channels.
Findings: Villagers were aware of antibiotics (Chiang Rai: 95.7%; Salavan: 86.4%; p<0.001) and drug
resistance (Chiang Rai: 74.8%; Salavan: 62.5%; p<0.001), but the usage of technical concepts for
antibiotics was dwarfed by local expressions like âanti-inflammatory medicineâ in Chiang Rai (87.6%;
95% confidence interval [CI]: 84.9â90.0) and âampiâ in Salavan (75.6%; 95% CI: 71.4â79.4).
Multivariate linear regression suggested that attitudes against over-the-counter antibiotics were linked
to 0.12 additional antibiotic use episodes from public healthcare providers in Chiang Rai (95% CI:
0.01 â 0.23) and 0.53 in Salavan (95% CI: 0.16 â 0.90).
Conclusions: Locally specific conceptions and counter-intuitive practices around antimicrobials can
complicate AMR communication efforts and entail unforeseen consequences. Overcoming
âknowledge deficitsâ alone will therefore be insufficient for global AMR behaviour change. We call
for an expansion of behavioural AMR strategies towards âAMR-sensitive interventionsâ that address
context-specific upstream drivers of antimicrobial use (e.g. unemployment insurance) and complement
education and awareness campaigns
Direct and seasonal legacy effects of the 2018 heat wave and drought on European ecosystem productivity
In summer 2018, central and northern Europe were stricken by extreme drought and heat (DH2018). The DH2018 differed from previous events in being preceded by extreme spring warming and brightening, but moderate rainfall deficits, yet registering the fastest transition between wet winter conditions and extreme summer drought. Using 11 vegetation models, we show that spring conditions promoted increased vegetation growth, which, in turn, contributed to fast soil moisture depletion, amplifying the summer drought. We find regional asymmetries in summer ecosystem carbon fluxes: increased (reduced) sink in the northern (southern) areas affected by drought. These asymmetries can be explained by distinct legacy effects of spring growth and of water-use efficiency dynamics mediated by vegetation composition, rather than by distinct ecosystem responses to summer heat/drought. The asymmetries in carbon and water exchanges during spring and summer 2018 suggest that future land-management strategies could influence patterns of summer heat waves and droughts under long-term warming
Effect of Weld Schedule on the Residual Stress Distribution of Boron Steel Spot Welds
Press-hardened boron steel has been utilized in anti-intrusion systems in automobiles, providing high strength and weight-saving potential through gage reduction. Boron steel spot welds exhibit a soft heat-affected zone which is surrounded by a hard nugget and outlying base material. This soft zone reduces the strength of the weld and makes it susceptible to failure. Additionally, different welding regimes lead to significantly different hardness distributions, making failure prediction difficult. Boron steel sheets, welded with fixed and adaptive schedules, were characterized. These are the first experimentally determined residual stress distributions for boron steel resistance spot welds which have been reported. Residual strains were measured using neutron diffraction, and the hardness distributions were measured on the same welds. Additionally, similar measurements were performed on spot welded DP600 steel as a reference material. A correspondence between residual stress and hardness profiles was observed for all welds. A significant difference in material properties was observed between the fixed schedule and adaptively welded boron steel samples, which could potentially lead to a difference in failure loads between the two boron steel welds
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