Dolphin echolocation behaviour during active long-range target approaches

Financial support was provided by the US Office of Naval Research Code 32 (Mine Countermeasures, Acoustics Phenomenology & Modeling Group). M.L. and P.T.M. were funded by frame grants from the National Danish Research Council (Det Frie Forskningsråd) and by a Semper Ardens grant from the Carlsberg Foundation. M.L.’s travel expenses were covered by grants from Augustinus Fonden and DAS-Fonden (Danish Acoustical Society, Dansk Akustisk Selskab). F.H.J. was funded by an AIAS-COFUND fellowship from Aarhus Institute of Advanced Studies under the EU's Seventh Framework Programme (Agreement No. 609033).Echolocating toothed whales generally adjust click intensity and rate according to target range to ensure that echoes from targets of interest arrive before a subsequent click is produced, presumably facilitating range estimation from the delay between clicks and returning echoes. However, this click-echo-click paradigm for the dolphin biosonar is mostly based on experiments with stationary animals echolocating fixed targets at ranges below ∼120 m. Therefore, we trained two bottlenose dolphins instrumented with a sound recording tag to approach a target from ranges up to 400 m and either touch the target (subject TRO) or detect a target orientation change (subject SAY). We show that free-swimming dolphins dynamically increase interclick interval (ICI) out to target ranges of ∼100 m. TRO consistently kept ICIs above the two-way travel time (TWTT) for target ranges shorter than ∼100 m, whereas SAY switched between clicking at ICIs above and below the TWTT for target ranges down to ∼25 m. Source levels changed on average by 17log10(target range), but with considerable variation for individual slopes (4.1 standard deviations for by-trial random effects), demonstrating that dolphins do not adopt a fixed automatic gain control matched to target range. At target ranges exceeding ∼100 m, both dolphins frequently switched to click packet production in which interpacket intervals exceeded the TWTT, but ICIs were shorter than the TWTT. We conclude that the click-echo-click paradigm is not a fixed echolocation strategy in dolphins, and we demonstrate the first use of click packets for free-swimming dolphins when solving an echolocation task.Publisher PDFPeer reviewe

Vital Indicators of the Rural and Agricultural Population in the S. R. Croatia — The Demographical Breakdown

Stanovništvo SR Hrvatske nalazi se na kraju razdoblja demografske tranzicije. Godine 1982. imalo je natalitet 14,5 promila, mortalitet 11,0 promila, prirodni priraštaj 3,5 promila, a vitalni indeks 134,4. Ovakvo kretanje biovitalnih stopa rezultat je utjecaja industrijalizacijskih procesa na demografski razvitak, napose deagrarizacije. Postoje tipična seoska područja sa sekularnim trendovima niskog nataliteta, a nagli je pad naročito izražen između dva posljednja popisna razdoblja (1971—1981), tako da je 1981. imalo negativni prirodni priraštaj čak 49 općina, u kojima živi 24% ukupnog stanovništva republike. Na osnovi popisa stanovništva podataka i demografske statistike, autor analizira promjene u demografskim strukturama seoskog i poljoprivrednog stanovništva (po zajednicama općina i regijama), usporedno kretanje reproduktivnih stopa poljoprivrednog i nepoljoprivrednog stanovništva te seoskog i »neseoskog « stanovništva, starenje seoskog i poljoprivrednog stanovništva te obrazovnu strukturu poljoprivrednog stanovništva. Zaključno ističe da je većina seoskog i poljoprivrednog stanovništva u poodmakloj dobi, da je biološko pomlađivanje simbolično, te da su i dalje naglašene aspiracije prema nepoijoprivrednim zanimanjima.The population of the S. R. Croatia is at the end of a period of demographic transition. In 1982 the birth rate was 14.5 per thousand, the death rate 11.0 per thousand, the natural population increase 3.5 per thousand, and the viital index 134.4. This change in biovital rates is the result of the influence of industrialization on demographic development, and in particular the result of deagrarization. Some rural regions have typical age-old trends towards a low birth-rate, but the sudden decrease came to expression especially between the last two censuses (1971—1981), so that as many as 49 communes had a negative natural population increase in 1981. 24% of the total population of the republic lives in these communes. The author uses data from population censuses and demographic statistics to analyze changes in the demographic structure of the rural and agricultural population (according to communities and regions). He compares changes in rates of reproduction between the agricultural and the non-agricultural population, and between the rural and the »non-rural« population, studies the ageing of the rural and agricultural population, and the educational structure of the agricultural population. He concludes that most of the rural and agricultural population is aged, that biological rejuvenation is symbolic, and that aspirations towards noo-agricultural occupationstions are still very strong

Implications of porpoise echolocation and dive behaviour on passive acoustic monitoring

Funding: The post-doctoral position for J.D.J.M. was funded by a FNU – Danish Natural Science Research Council grant to P.T.M. This study was also funded by the German Federal Agency for Nature Conservation via the grants “Effects of underwater noise on marine vertebrates” (Cluster 7, Z1.2-53302/2010/14) and “Under Water Noise Effects—UWE” (Project No. FKZ 3515822000). The contribution by T.A.M. was funded under the ACCURATE project (U.S. Navy Living Marine Resources Program, Contract No. N3943019C2176) and CEAUL (funded by FCT—Fundação para a Ciência e a Tecnologia, Portugal, through Project No. UIDB/00006/2020).Harbour porpoises are visually inconspicuous but highly soniferous echolocating marine predators that are regularly studied using passive acoustic monitoring (PAM). PAM can provide quality data on animal abundance, human impact, habitat use, and behaviour. The probability of detecting porpoise clicks within a given area ( P ̂ ) is a key metric when interpreting PAM data. Estimates of P ̂ can be used to determine the number of clicks per porpoise encounter that may have been missed on a PAM device, which, in turn, allows for the calculation of abundance and ideally non-biased comparison of acoustic data between habitats and time periods. However, P ̂ is influenced by several factors, including the behaviour of the vocalising animal. Here, the common implicit assumption that changes in animal behaviour have a negligible effect on P ̂ between different monitoring stations or across time is tested. Using a simulation-based approach informed by acoustic biologging data from 22 tagged harbour porpoises, it is demonstrated that porpoise behavioural states can have significant (up to 3× difference) effects on P ̂ . Consequently, the behavioural state of the animals must be considered in analysis of animal abundance to avoid substantial over- or underestimation of the true abundance, habitat use, or effects of human disturbance.Publisher PDFPeer reviewe

Antibiotics increase gut metabolism and antioxidant proteins and decrease acute phase response and necrotizing enterocolitis in preterm neonates

BACKGROUND: The appropriate use of antibiotics for preterm infants, which are highly susceptible to develop necrotizing enterocolitis (NEC), is not clear. While antibiotic therapy is commonly used in neonates with NEC symptoms and sepsis, it remains unknown how antibiotics may affect the intestine and NEC sensitivity. We hypothesized that broad-spectrum antibiotics, given immediately after preterm birth, would reduce NEC sensitivity and support intestinal protective mechanisms. METHODOLOGY/PRINCIPAL FINDINGS: Preterm pigs were treated with antibiotics for 5 d (oral and systemic doses of gentamycin, ampicillin and metrodinazole; AB group) and compared with untreated pigs. Only the untreated pigs showed evidence of NEC lesions and reduced digestive function, as indicated by lowered villus height and activity of brush border enzymes. In addition, 53 intestinal and 22 plasma proteins differed in expression between AB and untreated pigs. AB treatment increased the abundance of intestinal proteins related to carbohydrate and protein metabolism, actin filaments, iron homeostasis and antioxidants. Further, heat shock proteins and the complement system were affected suggesting that all these proteins were involved in the colonization-dependent early onset of NEC. In plasma, acute phase proteins (haptoglobin, complement proteins) decreased, while albumin, cleaved C3, ficolin and transferrin increased. CONCLUSIONS/SIGNIFICANCE: Depressed bacterial colonization following AB treatment increases mucosal integrity and reduces bacteria-associated inflammatory responses in preterm neonates. The plasma proteins C3, ficolin, and transferrin are potential biomarkers of the colonization-dependent NEC progression in preterm neonates

Cognitive Abilities in the Wild: Population-scale game-based cognitive assessment

Psychology and the social sciences are undergoing a revolution: It has become increasingly clear that traditional lab-based experiments fail to capture the full range of differences in cognitive abilities and behaviours across the general population. Some progress has been made toward devising measures that can be applied at scale across individuals and populations. What has been missing is a broad battery of validated tasks that can be easily deployed, used across different age ranges and social backgrounds, and employed in practical, clinical, and research contexts. Here, we present Skill Lab, a game-based approach allowing the efficient assessment of a suite of cognitive abilities. Skill Lab has been validated outside the lab in a crowdsourced population-size sample recruited in collaboration with the Danish Broadcast Company (Danmarks Radio, DR). Our game-based measures are five times faster to complete than the equivalent traditional measures and replicate previous findings on the decline of cognitive abilities with age in a large population sample. Furthermore, by combining the game data with an in-game survey, we demonstrate that this unique dataset has implication for key questions in social science, challenging the Jack-of-all-Trades theory of entrepreneurship and provide evidence for risk preference being independent of executive functioning.Comment: 11 pages, 4 figures, and 2 table