20,346 research outputs found
An Evaluation of Truncated Sequential Test
The development of sequential analysis has led to the proposal of tests that are more economical in that the Average Sample Number (A. S. N.) of the sequential test is smaller than the sample size of the fixed sample test. Although these tests usually have a smaller A. S. N. than the equivelent fixed sample procedure, there still remains the possibility that an extremely large sample size will be necessary to make a decision. To remedy this, truncated sequential tests have been developed.
A method of truncation for testing a composite hypotheses is studied. This method is formed by mixing a fixed sample test and a sequential test and is applied to the exponential distribution and normal distribution to establish its usefulness.
It is proved that our truncation method can give a similar Operating Characteristic (O. C.) curve to that of corresponding fixed sample test if the test parameters are properly chosen. The average sample size required by our truncation method as compared with other existing truncation methods gives us a satisfactory result. Though the truncation method we suggested in this study is not an optimum truncation, it is still worthwhile, especially, when we are interested in the testing of a composite hypotheses
Moduli of sheaves and the Chow group of K3 surfaces
Let X be a projective complex K3 surface. Beauville and Voisin singled out a
0-cycle c_X on X of degree 1: it is represented by any point lying on a
rational curve in X. Huybrechts proved that the second Chern class of a rigid
simple vector-bundle on X is a multiple of the Beauville-Voisin class c_X if
certain hypotheses hold and he conjectured that the additional hypotheses are
unnecessary. We believe that the following generalization of Huybrechts'
conjecture holds. Let M and N be moduli spaces of stable pure sheaves on X
(with fixed cohomological Chern characters) and suppose that they have the same
dimension: then the set whose elements are second Chern classes of sheaves
parametrized by the closure of M (in the corresponding moduli spaces of
semistable sheaves) is equal to the set whose elements are second Chern classes
of sheaves parametrized by the closure of N after a translation by a suitable
multiple of c_X (so that degrees match). We will prove that the above statement
holds under some additional assumptions.Comment: Deleted a footnote and replaced it by a sentence in the main body of
the pape
Angiotensin-converting enzyme genotypes in hypertensive patients with left ventricular hypertrophy
published_or_final_versio
A convex formulation for hyperspectral image superresolution via subspace-based regularization
Hyperspectral remote sensing images (HSIs) usually have high spectral
resolution and low spatial resolution. Conversely, multispectral images (MSIs)
usually have low spectral and high spatial resolutions. The problem of
inferring images which combine the high spectral and high spatial resolutions
of HSIs and MSIs, respectively, is a data fusion problem that has been the
focus of recent active research due to the increasing availability of HSIs and
MSIs retrieved from the same geographical area.
We formulate this problem as the minimization of a convex objective function
containing two quadratic data-fitting terms and an edge-preserving regularizer.
The data-fitting terms account for blur, different resolutions, and additive
noise. The regularizer, a form of vector Total Variation, promotes
piecewise-smooth solutions with discontinuities aligned across the
hyperspectral bands.
The downsampling operator accounting for the different spatial resolutions,
the non-quadratic and non-smooth nature of the regularizer, and the very large
size of the HSI to be estimated lead to a hard optimization problem. We deal
with these difficulties by exploiting the fact that HSIs generally "live" in a
low-dimensional subspace and by tailoring the Split Augmented Lagrangian
Shrinkage Algorithm (SALSA), which is an instance of the Alternating Direction
Method of Multipliers (ADMM), to this optimization problem, by means of a
convenient variable splitting. The spatial blur and the spectral linear
operators linked, respectively, with the HSI and MSI acquisition processes are
also estimated, and we obtain an effective algorithm that outperforms the
state-of-the-art, as illustrated in a series of experiments with simulated and
real-life data.Comment: IEEE Trans. Geosci. Remote Sens., to be publishe
Extending Yioop! With Geographical Location Local Search
It is often useful when doing an internet search to get results based on our current location. For example, we might want such results when we search on restaurants, car service center, or hospitals. Current open source search engines like those based on Nutch do not provide this facility. Commercial engines like Google and Yahoo! provide this facility so it would be useful to incorporate it in an open source alternative. The goal of this project is to include location aware search in Yioop!(Pollett, 2012) by using geographical data from OpenStreetMap(“Open Street map wiki”, 2012) and hostip.info (“DMOZ”, n.d.) database to geolocate IP addresses
Decline in frequency of DD genotype in hypertensive patients with age
published_or_final_versio
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Trends in the utilisation of emergency departments in California, 2005-2015: a retrospective analysis.
ObjectiveTo examine current trends in the characteristics of patients visiting California emergency departments (EDs) in order to better direct the allocation of acute care resources.DesignA retrospective study.SettingWe analysed ED utilisation trends between 2005 and 2015 in California using non-public patient data from California's Office of Statewide Health Planning and Development.ParticipantsWe included all ED visits in California from 2005 to 2015.Primary and secondary outcome measuresWe analysed ED visits and visit rates by age, sex, race/ethnicity, payer and urban/rural trends. We further examined age, sex, race/ethnicity and urban/rural trends within each payer group for a more granular picture of the patient population. Additionally, we looked at the proportion of patients admitted from the ED and distribution of diagnoses.ResultsBetween 2005 and 2015, the annual number of ED visits increased from 10.2 to 14.2 million in California. ED visit rates increased by 27.8% (p<0.001), with the greatest increases among patients aged 5-19 (37.4%, p<0.001) and 45-64 years (41.1%, p<0.001), non-Hispanic Black and Hispanic patients (56.8% and 48.8%, p<0.001), the uninsured and Medicaid-insured (36.1%, p=0.002; 28.6%, p<0.001) and urban residents (28.3%, p<0.001). The proportion of ED visits resulting in hospitalisation decreased by 18.3%, with decreases across all payer groups.ConclusionsOur findings reveal an increasing demand for emergency care and may reflect current limitations in accessing care in other parts of the healthcare system. Policymakers may need to recognise the increasingly vital role that EDs are playing in the provision of care and consider ways to incorporate this changing reality into the delivery of health services
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