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Estimating the stochastic uncertainty in sample-based estimates of infant mortality in Ghana
The Infant Mortality Rate (IMR) is an important population health statistic often used as one of the indicators of the health status of a nation. In many countries lacking adequate vital registration systems, sample methods are used to estimate IMRs. However, evaluations of this approach are rare and the literature contains no assessments of the stochastic uncertainty underlying these estimated IMRs. Stochastic uncertainty reflects the fact that even where the underlying IMR is constant in a small population over time, there is a likelihood of yearly fluctuation in its empirical observations even if it is measured from a complete count of the events of interest. In this study a method is presented that can be used to assess this stochastic uncertainty. We use the country of Ghana as a case study for this purpose. The method, a beta-binomial model, is described, tested for validity, and illustrated using 2014 sample-based estimates of IMR for 13 sample regions in Ghana. As such, the approach we described regarding the revision of sample-based IMR estimates is aimed at taking into account of the stochastic uncertainty while preserving the information concerning the uncertainty due to sampling. In applying the method to Ghana, we find that the sample-based IMR estimates perform well in accounting for stochastic uncertainty and could be applied elsewhere
Estimating the underlying infant mortality rates for small populations, including those reporting zero infant deaths: A case study of counties in California
Infant mortality is an important population health statistic that is often used to make health policy decisions. For a small population, an infant mortality rate is subject to high levels of uncertainty and may not indicate the âunderlyingâ mortality regime affecting the population. This situation leads some agencies to either not report infant mortality for these populations or report infant mortality aggregated over space, time or both. A method is presented for estimating âunderlyingâ infant mortality rates that reflect the intrinsic mortality regimes of small populations. The method is described and illustrated in a case study by estimating IMRs for the 15 counties in California where zero infant deaths are reported at the county level for the period 2009-2011. We know that among these 15 counties there are 50 infant deaths reported at the state level but not for the counties in which they occurred. The methodâs validity is tested using a synthetic population in the form of a simulated data set generated from a model life table infant mortality rate, representing Level 23 of the West Family Model Life Table for both sexes. The test indicates that the method is capable of producing estimates that represent underlying rates. In this regard, the method described here may assist in the generation of information about the health status of small populations
A Psychotic Reaction in a Sex-Chromatin Negative Female
Neuropsychiatric disorders found in association with Turner's syndrome (gonadal agenesis) are unusual. The case report describes a patient with Turner's syndrome who suffered an acute psychotic reaction. A brief review of the literature concerning this association is surveyed.S. Afr. Med. J., 47, 146 (1973
Magma mixing and high fountaining during the 1959 K Ä«lauea Iki eruption, Hawai'i
The 1959 KÄ«lauea Iki eruption provides a unique opportunity to investigate the process of shallow magma mixing, its impact on the magmatic volatile budget and its role in triggering and driving episodes of Hawaiian fountaining. Melt inclusions hosted by olivine record a continuous decrease in H2O concentration through the 17 episodes of the eruption, while CO2 concentrations correlate with the degree of post-entrapment crystallization of olivine on the inclusion walls. Geochemical data, when combined with the magma budget and with contemporaneous eruption observations, show complex mixing between episodes involving hot, geochemically heterogeneous melts from depth, likely carrying exsolved vapour, and melts which had erupted at the surface, degassed and drained-back into the vent. The drained-back melts acted as a coolant, inducing rapid cooling of the more primitive melts and their olivines at shallow depths and inducing crystallization and vesiculation and triggering renewed fountaining. A consequence of the mixing is that the melts became vapor-undersaturated, so equilibration pressures cannot be inferred from them using saturation models. After the melt inclusions were trapped, continued growth of vapor bubbles, caused by enhanced post-entrapment crystallization, sequestered a large fraction of CO2 from the
melt within the inclusions. This study, while cautioning against accepting melt inclusion CO2
concentrations âas measuredâ in mixed magmas, also illustrates that careful analysis and
interpretation of post-entrapment modifications can turn this apparent challenge into a way to
yield novel useful insights into the geochemical controls on eruption intensity.IS was supported by a NERC-funded studentship and a USGS Jack Kleinman Grant for Volcano
Research. ME acknowledges NERC ion probe grant IMF376/0509. BHâs participation was
funded by NSF EAR-1145159. We acknowledge the NERC Edinburgh Ion Microprobe facility,
where we undertook the SIMS analyses.This version is the author accepted manuscript and will be under embargo until the 6th of June 2015. The final version has been published by Elsevier in Earth and Planetary Science Letters here: http://www.sciencedirect.com/science/article/pii/S0012821X14003264
Magma decompression rates during explosive eruptions of KiÌlauea volcano, Hawai'i, recorded by melt embayments
The decompression rate of magma as it ascends during volcanic eruptions is an important but poorly constrained parameter that controls many of the processes that influence eruptive behaviour. In this study we quantify decompression rates for basaltic magmas using volatile diffusion in olivine-hosted melt tubes (embayments) for three contrasting eruptions of KÄ«lauea volcano, Hawai'i. Incomplete exsolution of HâO, COâ and S from the embayment melts during eruptive ascent creates diffusion profiles that can be measured using microanalytical techniques, and then modelled to infer the average decompression rate. We obtain average rates of ~0.05-0.45 MPa s-1 for eruptions ranging from Hawaiian style fountains to basaltic subplinian, with the more intense eruptions having higher rates. The ascent timescales for these magmas vary from around ~5 to ~36 minutes from depths of ~2 to ~4 km respectively. Decompression-exsolution models based on the embayment data also allow for an estimate of the mass fraction of pre-existing exsolved volatiles within the magma body. In the eruptions studied this varies from 0.1-3.2 wt%, but does not appear to be the key control on eruptive intensity. Our results do not support a direct link between the concentration of pre-eruptive volatiles and eruptive intensity; rather they suggest that for these eruptions decompression rates are proportional to independent estimates of mass discharge rate. Although the intensity of eruptions is defined by the discharge rate, based on the currently available dataset of embayment analyses it does not appear to scale linearly with average decompression rate. This study demonstrates the utility of the embayment method for providing quantitative constraints on magma ascent during explosive basaltic eruptions
Walking through volcanic mud : the 2,100 year-old Acahualina footprints (Nicaragua) II: the Acahualina people, environmental conditions and motivation
We analyzed bare human footprints in Holocene tuff preserved in two pits in the Acahualinca barrio in the northern outskirts of Managua (Nicaragua). Lithology, volcanology, and age of the deposits are discussed in a companion paper (Schmincke et al. Bull Volcanol doi: 10.1007/s00445-008-0235-9, 2008). The footprint layer occurs within a series of rapidly accumulated basalticâandesitic tephra that is regionally correlated to the Masaya Triple Layer Tephra. The people were probably trying to escape from a powerful volcanic eruption at Masaya Caldera 20 km farther south that occurred at 2.1 ka BP. We subdivided the swath of footprints, up to 5.6 m wide, in the northern pit (Pit I) into (1) a central group of footprints made by about six individuals, the total number being difficult to determine because people walked in each otherâs footsteps one behind the other and (2) two marginal groups on either side of the central group with more widely spaced tracks. The western band comprises tracks of three adjacent individuals and an isolated single footprint farther out. The eastern marginal area comprises an inner band of deep footprints made by three individuals and, farther out, three clearly separated individuals. We estimate the total number of people as 15â16. In the southern narrow and smaller pit (Pit II), we recognize tracks of ca. 12 individuals, no doubt made by the same group. The group represented in both pits probably comprised male and female adults, teenagers and children based on differences in length of footprints and of strides and depth of footprints made in the soft wet ash. The smallest footprints (probably made by children) occur in the central group, where protection was most effective. The footprint layer is composed of a lower 5â15-cm thick, coarse-grained vesicle tuff capped by a medium to fine-grained tuff up to 3 cm thick. The surface on which the people walked was muddy, and the soft ash was squeezed up on the sides of the foot imprints and between toes. Especially, deep footprints are mainly due to local thickening of the water-rich ash, multiple track use, and differences in weight of individuals. The excellent preservation of the footprints, ubiquitous mudcracks, sharp and well-preserved squeeze-ups along the margins of the tracks and toe imprints, and the absence of raindrop impressions all suggest that the eruption occurred during the dry season. The people walked at a brisk pace, as judged from the tight orientation of the swath and the length of the strides. The directions of a major erosional channel in the overlying deposits that probably debouched into Lake Managua and the band of footprints are strictly parallel, indicating that people walked together in stride along the eastern margin of a channel straight toward the lake shore, possibly a site with huts and/or boats for protection and/or escape
Methods for Rapidly Processing Angular Masks of Next-Generation Galaxy Surveys
As galaxy surveys become larger and more complex, keeping track of the
completeness, magnitude limit, and other survey parameters as a function of
direction on the sky becomes an increasingly challenging computational task.
For example, typical angular masks of the Sloan Digital Sky Survey contain
about N=300,000 distinct spherical polygons. Managing masks with such large
numbers of polygons becomes intractably slow, particularly for tasks that run
in time O(N^2) with a naive algorithm, such as finding which polygons overlap
each other. Here we present a "divide-and-conquer" solution to this challenge:
we first split the angular mask into predefined regions called "pixels," such
that each polygon is in only one pixel, and then perform further computations,
such as checking for overlap, on the polygons within each pixel separately.
This reduces O(N^2) tasks to O(N), and also reduces the important task of
determining in which polygon(s) a point on the sky lies from O(N) to O(1),
resulting in significant computational speedup. Additionally, we present a
method to efficiently convert any angular mask to and from the popular HEALPix
format. This method can be generically applied to convert to and from any
desired spherical pixelization. We have implemented these techniques in a new
version of the mangle software package, which is freely available at
http://space.mit.edu/home/tegmark/mangle/, along with complete documentation
and example applications. These new methods should prove quite useful to the
astronomical community, and since mangle is a generic tool for managing angular
masks on a sphere, it has the potential to benefit terrestrial mapmaking
applications as well.Comment: New version 2.1 of the mangle software now available at
http://space.mit.edu/home/tegmark/mangle/ - includes galaxy survey masks and
galaxy lists for the latest SDSS data release and the 2dFGRS final data
release as well as extensive documentation and examples. 14 pages, 9 figures,
matches version accepted by MNRA
Stronger or longer: Discriminating between Hawaiian and Strombolian eruption styles
The weakest explosive volcanic eruptions globally, Strombolian explosions and Hawaiian fountaining, are also the most common. Yet, despite over a hundred years of observations, no classifications have offered a convincing, quantitative way of demarcating these two styles. New observations show that the two styles are distinct in their eruptive time scale, with the duration of Hawaiian fountaining exceeding Strombolian explosions by âŒ300â10,000 s. This reflects the underlying process of whether shallow-exsolved gas remains trapped in the erupting magma or is decoupled from it. We propose here a classification scheme based on the duration of events (brief explosions versus prolonged fountains) with a cutoff at 300 s that separates transient Strombolian explosions from sustained Hawaiian fountains.The authors wish to acknowledge grants from NSF (EAR-0409303, 0810332, 1145159, 1427357) and ARRA (113153 via the Hawaiian Volcano Observatory), which funded this research.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1130/G37423.
Hybrid exotic meson with J^{PC}=1^{-+} in AdS/QCD
We investigate the hybrid exotic meson with within the
framework of an AdS/QCD model. Introducing a holographic field dual to the
operator for hybrid exotic meson, we obtain the eigen-value equation for its
mass. Fixing all free parameters by QCD observables such as the -meson
mass, we predict the masses of the hybrid exotic meson. The results turn out to
be for the ground state, and for the
first excited one. Being compared with the existing experimental data for the
, which is known to be , the
present result seems to be qualitative in agreement with it. We also predict
the decay constant of (1400): MeV.Comment: 10 pages, 1 Tabl
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