285 research outputs found
Scientific Rationale and Requirements for a Global Seismic Network on Mars
Following a brief overview of the mission concepts for a Mars Global Network Mission as of the time of the workshop, we present the principal scientific objectives to be achieved by a Mars seismic network. We review the lessons for extraterrestrial seismology gained from experience to date on the Moon and on Mars. An important unknown on Mars is the expected rate of seismicity, but theoretical expectations and extrapolation from lunar experience both support the view that seismicity rates, wave propagation characteristics, and signal-to-noise ratios are favorable to the collection of a scientifically rich dataset during the multiyear operation of a global seismic experiment. We discuss how particular types of seismic waves will provide the most useful information to address each of the scientific objectives, and this discussion provides the basis for a strategy for station siting. Finally, we define the necessary technical requirements for the seismic stations
Gravid Anopheles gambiae sensu stricto avoid ovipositing in Bermuda grass hay infusion and it's volatiles in two choice egg-count bioassays.
BACKGROUND: A number of mosquito species in the Culex and Aedes genera prefer to lay eggs in Bermuda grass (Cynodon dactylon) hay infusions compared to water alone. These mosquitoes are attracted to volatile compounds from the hay infusions making the infusions effective baits in gravid traps used for monitoring vectors of arboviral and filarial pathogens. Since Bermuda grass is abundant and widespread, it is plausible to explore infusions made from it as a potential low cost bait for outdoor monitoring of the elusive malaria vector Anopheles gambiae s.s. METHODS: This study investigated preferential egg laying of individual An. gambiae s.s. in hay infusion or in tap water treated with volatiles detected in hay infusion headspace compared to tap water alone, using two-choice egg-count bioassays. Infusions were prepared by mixing 90 g of dried Bermuda grass (hay) with 24 L of unchlorinated tap water in a bucket, and leaving it for 3 days at ambient temperature and humidity. The volatiles in the headspace of the hay infusion were sampled with Tenax TA traps for 20 h and analysed using gas chromatography coupled to mass spectrometry. RESULTS: In total, 18 volatiles were detected in the infusion headspace. Nine of the detected compounds and nonanal were selected for bioassays. Eight of the selected compounds have previously been suggested to attract/stimulate egg laying in An. gambiae s.s. Gravid females were significantly (p < 0.05) less likely to lay eggs in hay infusion dilutions of 25, 50 and 100 % and in tap water containing any of six compounds (3-methylbutanol, phenol, 4-methylphenol, nonanal, indole, and 3-methylindole) compared to tap water alone. The oviposition response to 10 % hay infusion or any one of the remaining four volatiles (4-hepten-1-ol, phenylmethanol, 2-phenylethanol, or 4-ethylphenol) did not differ from that in tap water. CONCLUSIONS: Anopheles gambiae s.s. prefers to lay eggs in tap water rather than Bermuda grass hay infusion. This avoidance of the hay infusion appears to be mediated by volatile organic compounds from the infusion. It is, therefore, unlikely that Bermuda grass hay infusion as formulated and used in gravid traps for Culex and Aedes mosquitoes will be suitable baits for monitoring gravid An. gambiae s.s
Analysing chemical attraction of gravid Anopheles gambiae sensu stricto with modified BG-Sentinel traps.
BACKGROUND: Cues that guide gravid Anopheles gambiae sensu lato to oviposition sites can be manipulated to create new strategies for monitoring and controlling malaria vectors. However, progress towards identifying such cues is slow in part due to the lack of appropriate tools for investigating long-range attraction to putative oviposition substrates. This study aimed to develop a relatively easy-to-use bioassay system that can effectively analyse chemical attraction of gravid Anopheles gambiae sensu stricto. METHODS: BG-Sentinelâą mosquito traps that use fans to dispense odourants were modified to contain aqueous substrates. Choice tests with two identical traps set in an 80 m(2) screened semi-field system were used to analyse the catch efficacy of the traps and the effectiveness of the bioassay. A different batch of 200 gravid An. gambiae s.s. was released on every experimental night. Choices tested were (1) distilled versus distilled water (baseline) and (2) distilled water versus soil infusion. Further, comparisons were made of distilled water and soil infusions both containing 150 g/l of Sodium Chloride (NaCl). Sodium Chloride is known to affect the release rate of volatiles from organic substrates. RESULTS: When both traps contained distilled water, 45% (95 confidence interval (CI) 33-57%) of all released mosquitoes were trapped. The proportion increased to 84% (95 CI 73-91%) when traps contained soil infusions. In choice tests, a gravid female was twice as likely to be trapped in the test trap with soil infusion as in the trap with distilled water (odds ratio (OR) 1.8, 95% CI 1.3-2.6). Furthermore, the attraction of gravid females towards the test trap with infusion more than tripled (OR 3.4, 95% CI 2.4-4.8) when salt was added to the substrates. CONCLUSION: Minor modifications of the BG-Sentinelâą mosquito trap turned it into a powerful bioassay tool for evaluating the orientation of gravid mosquitoes to putative oviposition substrates using olfaction. This study describes a useful tool for investigating olfactory attraction of gravid An. gambiae s.s. and provides additional evidence that gravid mosquitoes of this species are attracted to and can be baited with attractive substrates such as organic infusions over a distance of several metres
The barycentric motion of exoplanet host stars: tests of solar spin-orbit coupling
Empirical evidence suggests a tantalising but unproven link between various
indicators of solar activity and the barycentric motion of the Sun. The latter
is exemplified by transitions between regular and more disordered motion
modulated by the motions of the giant planets, and rare periods of retrograde
motion with negative orbital angular momentum. An examination of the
barycentric motion of exoplanet host stars, and their stellar activity cycles,
has the potential of proving or disproving the Sun's motion as an underlying
factor in the complex patterns of short- and long-term solar variability
indices, by establishing whether such correlations exist in other planetary
systems. A variety of complex patterns of barycentric motions of exoplanet host
stars is demonstrated, depending on the number, masses and orbits of the
planets. Each of the behavioural types proposed to correlate with solar
activity are also evident in exoplanet host stars: repetitive patterns
influenced by massive multiple planets, epochs of rapid change in orbital
angular momentum, and intervals of negative orbital angular momentum. The study
provides the basis for independent investigations of the widely-studied but
unproven suggestion that the Sun's motion is somehow linked to various
indicators of solar activity. We show that, because of the nature of their
barycentric motions, the host stars HD168443 and HD74156 offer particularly
powerful tests of this hypothesis.Comment: 7 pages, 3 figures. Accepted for publication in A&
Insights on the source of the 28 September 2018 Sulawesi tsunami, Indonesia based on spectral analyses and numerical simulations
The 28 September 2018 Sulawesi tsunami has been a puzzle because extreme deadly tsunami waves were generated
following an Mw 7.5 strike-slip earthquake, while such earthquakes
are not usually considered to produce large tsunamis. Here, we
obtained, processed and analyzed two sea level records of the
tsunami in the near-field (Pantoloan located inside the Palu Bay)
and far-field (Mamuju located outside the Palu Bay) and conducted
numerical simulations to shed light on the tsunami source. The two
tide gauges recorded maximum tsunami trough-to-crest heights of
380 and 24 cm, respectively, with respective dominating wave
periods of 3.6-4.4 and 10 min, and respective high-energy wave
duration of 5.5 and [14 h. The two observed waveforms were
significantly different with wave amplitude and period ratios of
*16 and *3, respectively. We infer tsunamigenic source dimen19
sions of 3.4â4.1 km and 32.5 km, for inside and outside of the Palu
Bay, respectively. Our numerical simulations fairly well repro21
duced both tsunami observations in Pantoloan and Mamuju; except
for the arrival time in Mamuju. However, it was incapable of
reproducing the maximum reported coastal amplitudes of 6â11 m.
It is possible that these two sources are different parts of the same tectonic source. A bay oscillation mode of *85 min was revealed
for the Palu Bay through numerical modeling. Actual sea surface disturbances and landslide-generated waves were captured by two
video recordings from inside the Palu Bay shortly after the earthquake. It is possible that a large submarine landslide contributed to
and intensified the Sulawesi tsunami. We identify the southern part of the Palu Bay, around the latitude of -0.82o
S, as the most likely location of a potential landslide based on our backward tsunami ray tracing analysis. However, marine geological data from the Palu Bay are required to confirm such hypothesis
Observing calving-generated ocean waves with coastal broadband seismometers, Jakobshavn IsbrĂŠ, Greenland
We use time-lapse photography, MODIS satellite imagery, ocean wave measurements and
regional broadband seismic data to demonstrate that icebergs that calve from Jakobshavn IsbrĂŠ,
Greenland, can generate ocean waves that are detectable over 150 km from their source.We use time-lapse photography, MODIS satellite imagery, ocean wave measurements and
regional broadband seismic data to demonstrate that icebergs that calve from Jakobshavn IsbrĂŠ,
Greenland, can generate ocean waves that are detectable over 150 km from their source. The waves,
which are recorded seismically, have distinct spectral peaks, are not dispersive and persist for several
hours. On the basis of these observations, we suggest that calving events at Jakobshavn IsbrĂŠ can
stimulate seiches, or basin eigenmodes, in both Ilulissat Icefjord and Disko Bay. Our observations
furthermore indicate that coastal, land-based seismometers located near calving termini (e.g. as part
of the new Greenland Ice Sheet Monitoring Network (GLISN)) can aid investigations into the largely
unexplored, oceanographic consequences of iceberg calving.Funding for this project was provided by NASAâs Cryospheric
Sciences Program (NNG06GB49G), the US National
Science Foundation (ARC0531075, ARC0909552 and
ANT0944193), the Swiss National Science Foundation
(200021-113503/1) and a Cooperative Institute for Arctic
Research (CIFAR) International Polar Year (IPY) student
fellowship under US National Oceanic and Atmospheric
Administration (NOAA) cooperative agreement NA17RJ1224
with the University of Alaska. The seismic data were col-
lected and distributed by the Greenland Ice Sheet Monitoring
Network (GLISN) federation and its members: data from
GDH were collected by the Geological Survey of Denmark
and Greenland (GEUS); data from ASI, ILU and SUMG were
collected by GEOFON; data from SFJ/SFJD were collected
by GEUS, GEOFON, Incorporated Research Institutions for
Seismology (IRIS) and the Comprehensive Test-Ban Treaty
Organization (CTBTO); and data from ILULI were collected
by ETH. We thank J. Brown and D. Podrasky for assistance
with fieldwork and D.R. MacAyeal and E.A. Okal for
discussions that led to and improved the manuscript. The
manuscript benefited from the comments of O. Sergienko,
an anonymous reviewer and editor P. Christoffersen.Ye
Cedrol, a malaria mosquito oviposition attractant is produced by fungi isolated from rhizomes of the grass Cyperus rotundus
A Taxonomy and Results from a Comprehensive Review of 28 Maternal Health Voucher Programmes
It is increasingly clear that Millennium Development Goal 4 and 5 will
not be achieved in many low- and middle-income countries with the
weakest gains among the poor. Recognizing that there are large
inequalities in reproductive health outcomes, the post-2015 agenda on
universal health coverage will likely generate strategies that target
resources where maternal and newborn deaths are the highest. In 2012,
the United States Agency for International Development convened an
Evidence Summit to review the knowledge and gaps on the utilization of
financial incentives to enhance the quality and uptake of maternal
healthcare. The goal was to provide donors and governments of the low-
and middle-income countries with evidenceinformed recommendations on
practice, policy, and strategies regarding the use of financial
incentives, including vouchers, to enhance the demand and supply of
maternal health services. The findings in this paper are intended to
guide governments interested in maternal health voucher programmes with
recommendations for sustainable implementation and impact. The Evidence
Summit undertook a systematic review of five financing strategies. This
paper presents the methods and findings for vouchers, building on a
taxonomy to catalogue knowledge about voucher programme design and
functionality. More than 120 characteristics under five major
categories were identified: programme principles (objectives and
financing); governance and management; benefits package and beneficiary
targeting; providers (contracting and service pricing); and
implementation arrangements (marketing, claims processing, and
monitoring and evaluation). Among the 28 identified maternal health
voucher programmes, common characteristics included: a stated objective
to increase the use of services among the means-tested poor;
contracted-out programme management; contracting either exclusively
private facilities or a mix of public and private providers;
prioritizing community-based distribution of vouchers; and tracking
individual claims for performance purposes. Maternal voucher programmes
differed on whether contracted providers were given training on
clinical or administrative issues; whether some form of service
verification was undertaken at facility or communitylevel; and the
relative size of programme management costs in the overall programme
budget. Evidence suggests voucher programmes can serve populations with
national-level impact. Reaching scale depends on whether the voucher
programme can: (i) keep management costs low, (ii) induce a large
demand-side response among the bottom two quintiles, and (iii) achieve
a quality of care that translates a greater number of facility-based
deliveries into a reduction in maternal morbidity and mortality
Earthquake scaling relations for mid-ocean ridge transform faults
Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): B12302, doi:10.1029/2004JB003110.A mid-ocean ridge transform fault (RTF) of length L, slip rate V, and moment release rate dot above M can be characterized by a seismic coupling coefficient Ï = A E/A T, where A E ⌠dot above M/V is an effective seismic area and A T â L 3/2 V â1/2 is the area above an isotherm T ref. A global set of 65 RTFs with a combined length of 16,410 km is well described by a linear scaling relation (1) A E â A T, which yields Ï = 0.15 ± 0.05 for T ref = 600°C. Therefore about 85% of the slip above the 600°C isotherm must be accommodated by subseismic mechanisms, and this slip partitioning does not depend systematically on either V or L. RTF seismicity can be fit by a truncated Gutenberg-Richter distribution with a slope ÎČ = 2/3 in which the cumulative number of events N 0 and the upper cutoff moment M C = ÎŒD C A C depend on A T. Data for the largest events are consistent with a self-similar slip scaling, D C â A C 1/2, and a square root areal scaling (2) A C â A T 1/2. If relations 1 and 2 apply, then moment balance requires that the dimensionless seismic productivity, Îœ0 â inline equation 0/A T V, should scale as Îœ0 â A T â1/4, which we confirm using small events. Hence the frequencies of both small and large earthquakes adjust with A T to maintain constant coupling. RTF scaling relations appear to violate the single-mode hypothesis, which states that a fault patch is either fully seismic or fully aseismic and thus implies A C †A E. The heterogeneities in the stress distribution and fault structure responsible for relation 2 may arise from a thermally regulated, dynamic balance between the growth and coalescence of fault segments within a rapidly evolving fault zone.M.B. was supported by a NSF
Graduate Research Fellowship, a MIT Presidential Fellowship, and the
WHOI DOEI Fellowship. This research was supported by the Southern
California Earthquake Center. SCEC is funded by NSF Cooperative Agreement
EAR-0106924 and USGS Cooperative Agreement 02HQAG0008
Lessons learned and study results from HIVCore, an HIV implementation science initiative
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138261/1/jia21261.pd
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