127 research outputs found
How effectively do horizontal and vertical response strategies of long-finned pilot whales reduce sound exposure from naval sonar?
PJW was supported with studentships of The Netherlands Ministry of Defence (grant number 032.30370/01.02) and the VSB Foundation (grant number VSB.08/228-E) and Ren e Dekeling is acknowledged for making funding possible. The 3S project was supported by the US OfïŹce of Naval Research, The Netherlands Ministry of Defence, Royal Norwegian Navy and Norwegian Ministry of Defence, and by World Wildlife Fund Norway. PLT received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged.The behaviour of a marine mammal near a noise source can modulate the sound exposure it receives. We demonstrate that two long-finned pilot whales both surfaced in synchrony with consecutive arrivals of multiple sonar pulses. We then assess the effect of surfacing and other behavioural response strategies on the received cumulative sound exposure levels and maximum sound pressure levels (SPLs) by modelling realistic spatiotemporal interactions of a pilot whale with an approaching source. Under the propagation conditions of our model, some response strategies observed in the wild were effective in reducing received levels (e.g. movement perpendicular to the source's line of approach), but others were not (e.g. switching from deep to shallow diving; synchronous surfacing after maximum SPLs). Our study exemplifies how simulations of source-whale interactions guided by detailed observational data can improve our understanding about motivations behind behaviour responses observed in the wild (e.g., reducing sound exposure, prey movement).PostprintPeer reviewe
The Subak in Diaspora: Balinese Farmers and the Subak in South Sulawesi
The subak has a long history as an irrigatorsâ institution on Bali. It has also spread across Indonesia along with Balinese farmers who were resettled by colonial and post-colonial governments or who have migrated spontaneously since colonial times. While subaks have been much researched in Bali itself, little is known about subaks outside Bali. Luwu District in South Sulawesi is one of the areas where thousands of Balinese families settled in the last four decades. Based on research in this transmigration area, this paper analyzes the emergence and development of the subak in relation to the development of irrigation infrastructure of a state-built irrigation system. A comparison between two Balinese settlements in the same system shows that differences in infrastructural and managerial conditions and arrangements between parts of the irrigation system were major determinants of the institutional space allowed for the subak and ways in which the subaks developed
Modeling potential masking of echolocating sperm whales exposed to continuous 1â2 kHz naval sonar
This study was sponsored by the U.S. Living Marine Resources program, Office of Naval Research (ONR) Grant Nos. N00014-18-1-2062 and N00014-20-1-2709, UK Defence Science and Technology Laboratory (DSTL), French Direction gĂ©nĂ©rale de l'armement (DGA), and the Netherlands Ministry of Defence.Modern active sonar systems can (almost) continuously transmit and receive sound, which can lead to more masking of important sounds for marine mammals than conventional pulsed sonar systems transmitting at a much lower duty cycle. This study investigated the potential of 1â2âkHz active sonar to mask echolocation-based foraging of sperm whales by modeling their echolocation detection process. Continuous masking for an echolocating sperm whale facing a sonar was predicted for sonar sound pressure levels of 160âdB re 1 ÎŒPa2, with intermittent masking at levels of 120âdB re 1 ÎŒPa2, but model predictions strongly depended on the animal orientation, harmonic content of the sonar, click source level, and target strength of the prey. The masking model predicted lower masking potential of buzz clicks compared to regular clicks, even though the energy source level is much lower. For buzz clicks, the lower source level is compensated for by the reduced two-way propagation loss to nearby prey during buzzes. These results help to predict what types of behavioral changes could indicate masking in the wild. Several key knowledge gaps related to masking potential of sonar in echolocating odontocetes were identified that require further investigation to assess the significance of masking.Publisher PDFPeer reviewe
Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions
Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose-response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance. © The authors 2016
The Possibly Remnant Massive Outflow in G5.89-0.39: I - Observations and Initial MHD Simulations
We have obtained maps of the large scale outflow associated with the UCHII
regionG5.89-0.39 in CO and 13CO (J=3-2), SiO (J=8-7,J=5-4), SO2
(13(2,12)-13(1,13)) and H13CO+(J=4-3). From these maps we have been able to
determine the mass (3.3 M_sun), momentum (96 M_sun km/s), energy (3.5x10^{46}
erg), mechanical luminosity (141 L_sun), and mass loss rate
(~1x10^{-3}M_sun/yr) in the large scale outflow. The observationally derived
parameters were used toguide 3D magnetohydrodynamic models of the jet entrained
outflow. Through the combination of observations and simulations, we suggest
that the large scale outflowmay be inclined by approximately 45 deg to the line
of sight, and that the jet entraining the observed molecular outflow may have
been active for as little as 1000 years, half the kinematic age of the outflow.Comment: 27 Pages, 9 Figures, Accepted to ApJ. For full (High) resolution
figures, please see http://www.ism.ucalgary.ca/~pamela/papers/index.htm
First indications that northern bottlenose whales are sensitive to behavioural disturbance from anthropogenic noise
-Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attached dataloggers to 13 northern bottlenose whales and compared their natural sounds and movements to those of one individual exposed to escalating levels of 1â2âkHz upsweep naval sonar signals. At a received sound pressure level (SPL) of 98âdB re 1âÎŒPa, the whale turned to approach the sound source, but at a received SPL of 107âdB re 1âÎŒPa, the whale began moving in an unusually straight course and then made a near 180° turn away from the source, and performed the longest and deepest dive (94âmin, 2339âm) recorded for this species. Animal movement parameters differed significantly from baseline for more than 7âh until the tag fell off 33â36âkm away. No clicks were emitted during the response period, indicating cessation of normal echolocation-based foraging. A sharp decline in both acoustic and visual detections of conspecifics after exposure suggests other whales in the area responded similarly. Though more data are needed, our results indicate high sensitivity of this species to acoustic disturbance, with consequent risk from marine industrialization and naval activity
Modelling the broadband propagation of marine mammal echolocation clicks for click-based population density estimates
Funding: U.S. Office of Naval Research (ONR Grant No. N00014-14-1-0409); P.L.T. acknowledges funding received from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (Grant No. HR09011) and contributing institutions.Passive acoustic monitoring with widely-dispersed hydrophones has been suggested as a cost-effective method to monitor population densities of echolocating marine mammals. This requires an estimate of the area around each receiver over which vocalizations are detectedâthe âeffective detection areaâ (EDA). In the absence of auxiliary measurements enabling estimation of the EDA, it can be modelled instead. Common simplifying model assumptions include approximating the spectrum of clicks by flat energy spectra, and neglecting the frequency-dependence of sound absorption within the click bandwidth (narrowband assumption), rendering the problem amenable to solution using the sonar equation. Here, it is investigated how these approximations affect the estimated EDA and their potential for biasing the estimated density. EDA was estimated using the passive sonar equation, and by applying detectors to simulated clicks injected into measurements of background noise. By comparing model predictions made using these two approaches for different spectral energy distributions of echolocation clicks, but identical click source energy level and detector settings, EDA differed by up to a factor of 2 for Blainville's beaked whales. Both methods predicted relative density bias due to narrowband assumptions ranged from 5% to more than 100%, depending on the species, detector settings, and noise conditions.Publisher PDFPeer reviewe
The cosmic web for density perturbations of various scales
We follow the evolution of galaxy systems in numerical simulation. Our goal
is to understand the role of density perturbations of various scales in the
formation and evolution of the cosmic web. We perform numerical simulations
with the full power spectrum of perturbations, and with spectrum cut at long
wavelengths. Additionally, we have one model, where we cut the intermediate
waves. We analyze the density field and study the void sizes and density field
clusters in different models. Our analysis shows that the fine structure
(groups and clusters of galaxies) is created by small-scale density
perturbations of scale \Mpc. Filaments of galaxies and clusters are
created by perturbations of intermediate scale from to \Mpc,
superclusters of galaxies by larger perturbations. We conclude that the scale
of the pattern of the cosmic web is determined by density perturbations of
scale up to \Mpc. Larger perturbations do not change the pattern of
the web, but modulate the richness of galaxy systems, and make voids emptier.
The stop of the increase of the scale of the pattern of the cosmic web with
increasing scale of density perturbations can probably be explained as the
freezing of the web at redshift .Comment: 12 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
J0454-0309: Evidence for a strong lensing fossil group falling into a poor galaxy cluster
We have discovered a strong lensing fossil group (J0454) at z=0.26, projected
near the well-studied cluster MS0451-0305. Using multicolour Subaru/Suprime-Cam
and CFHT/Megaprime imaging together with Keck spectroscopy we identify member
galaxies. A VLT/FORS2 spectrum was taken to determine the redshifts of the
brightest elliptical and the lensed arc. Using HST/ACS images we determine the
group's weak lensing signal and model the strong lens system. This is the first
time that a fossil group is analysed with lensing methods. The X-ray luminosity
and temperature are derived from XMM-Newton data.
We find two filaments extending over 4 Mpc, and within the virial radius we
identify 31 members spectroscopically and 33 via the red sequence with i<22
mag. They segregate into spirals and a dynamically cooler central concentration
of ellipticals with a velocity dispersion of 480 km/s. Weak lensing and cluster
richness relations yield r200 = 830 kpc and M200 = 0.85 x 10^14 Msun. The
brightest group galaxy (BGG) is inconsistent with the dynamic centre of J0454.
It strongly lenses a galaxy at z~2.1, and we model the lens with a
pseudo-isothermal elliptical mass distribution. A large external shear requires
that the BGG must be offset from J0454's dark halo centre by at least 90-130
kpc. The X-ray halo is offset by 24 kpc from the BGG, shows no signs of a
cooling flow and is well described by a beta-model. With L = 1.4 x 10^43 erg/s
J0454 falls well onto standard X-ray cluster scaling relations, but appears
cooler (1.1 keV) than expected (2 keV). We conclude that J0454 consists of two
systems, a sparse cluster and an infalling fossil group, the latter seeding the
BCG. An alternative explanation is that galaxies in a filament, projected along
the line of sight, stream towards the denser fossil group.Comment: 20 pages, 17 figures; Identical to the publication in A+A. Small
language corrections. Minor additions: We check the influence of individual
galaxy haloes to the external shear (Sect. 8.1.1). Alternative interpretation
of the data: Galaxies ina filament projected along the l.o.s. fall into the
fossil group (Section 8.1.2
Living Law, Legal Pluralism, and Corruption in Post-Soviet Uzbekistan
This paper aims to explore the multifaceted meaning, logic, and morality of informal transactions in order to better understand the social context that informs the meaning of corruption and bribery in post-Soviet Uzbekistan. It will be argued that the informal transactions in Uzbek society reflect different cultural and functional meanings from those in most of the Western world, and hence transactions that from a Western-centric perspective would be labelled as bribes can be morally accepted transactions in the Uzbek cultural context. If this is true, there may be reasons to re-evaluate the relevance of the Western-centric interpretations of corruption in the context of Uzbekistan, and possibly other Central Asian countries. These issues will be investigated with reference to observations and informal interviews from post-Soviet Uzbekistan. This study is based on three periods of ethnographic field research between 2009 and 2012 in the Ferghana Province of Uzbekistan. It draws on concepts of âliving lawâ and legal pluralism to provide a theoretical framework
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