616 research outputs found
Minimax Estimation of Nonregular Parameters and Discontinuity in Minimax Risk
When a parameter of interest is nondifferentiable in the probability, the
existing theory of semiparametric efficient estimation is not applicable, as it
does not have an influence function. Song (2014) recently developed a local
asymptotic minimax estimation theory for a parameter that is a
nondifferentiable transform of a regular parameter, where the nondifferentiable
transform is a composite map of a continuous piecewise linear map with a single
kink point and a translation-scale equivariant map. The contribution of this
paper is two fold. First, this paper extends the local asymptotic minimax
theory to nondifferentiable transforms that are a composite map of a Lipschitz
continuous map having a finite set of nondifferentiability points and a
translation-scale equivariant map. Second, this paper investigates the
discontinuity of the local asymptotic minimax risk in the true probability and
shows that the proposed estimator remains to be optimal even when the risk is
locally robustified not only over the scores at the true probability, but also
over the true probability itself. However, the local robustification does not
resolve the issue of discontinuity in the local asymptotic minimax risk
Maximum likelihood drift estimation for a threshold diffusion
We study the maximum likelihood estimator of the drift parameters of a
stochastic differential equation, with both drift and diffusion coefficients
constant on the positive and negative axis, yet discontinuous at zero. This
threshold diffusion is called drifted Oscillating Brownian motion.For this
continuously observed diffusion, the maximum likelihood estimator coincide with
a quasi-likelihood estimator with constant diffusion term. We show that this
estimator is the limit, as observations become dense in time, of the
(quasi)-maximum likelihood estimator based on discrete observations. In long
time, the asymptotic behaviors of the positive and negative occupation times
rule the ones of the estimators. Differently from most known results in the
literature, we do not restrict ourselves to the ergodic framework: indeed,
depending on the signs of the drift, the process may be ergodic, transient or
null recurrent. For each regime, we establish whether or not the estimators are
consistent; if they are, we prove the convergence in long time of the properly
rescaled difference of the estimators towards a normal or mixed normal
distribution. These theoretical results are backed by numerical simulations
Added value of second biopsy target in screen-detected widespread suspicious breast calcifications
Introduction: There is controversy on the optimal workâup of screenâdetected widespread breast calcifications: whether to biopsy a single target or multiple targets. This study evaluates agreement between multiple biopsy targets within the same screenâdetected widespread (â„25 mm) breast calcification to determine if the second biopsy adds value.
Methods: Retrospective observational study of women screened in a statewide general population risk breast cancer mammographic screening program from 2009 to 2016. Screening episodes recalled for widespread calcifications where further views indicated biopsy, and two or more separate target areas were sampled within the same lesion were included. Percentage agreement and Cohen\u27s Kappa were calculated.
Results: A total of 293317 women were screened during 761124 separate episodes with recalls for widespread calcifications in 2355 episodes. In 171 women, a second target was biopsied within the same lesion. In 149 (86%) cases, the second target biopsy result agreed with the first biopsy (Îș = 0.6768). Agreement increased with increasing mammography score (85%, 86% and 92% for score 3, 4 and 5 lesions). Same day multiple biopsied lesions were three times more likely to yield concordant results compared to postâhoc second target biopsy cases.
Conclusion: While a single target biopsy is sufficient to discriminate a benign vs. malignant diagnosis in most cases, in 14% there is added value in performing a second target biopsy. Biopsies performed prospectively are more likely to yield concordant results compared to postâhoc second target biopsy cases, suggesting a single prospective biopsy may be sufficient when results are radiologicalâpathological concordant; discordance still requires repeat sampling
Specific protease activity indicates the degree of Pseudomonas aeruginosa infection in chronic infected wounds
Chronic non-healing wounds are a major health problem with resident bacteria strongly implicated in their impaired healing. A rapid-screen to provide detailed knowledge of wound bacterial populations would therefore be of value and help prevent unnecessary and indiscriminate use of antibioticsâa process associated with promoting antibiotic resistance. We analysed chronic wound fluid samples, which had been assessed for microbial content, using 20 different fluorescent labelled peptide substrates to determine whether protease activity correlated with the bacterial load. Eight of the peptide substrates showed significant release of fluorescence after reaction with some of the wound samples. Comparison of wound fluid protease activities with the microbiological data indicated that there was no correlation between bacterial counts and enzyme activity for most of the substrates tested. However, two of the peptide substrates produced a signal corresponding with the microbial data revealing a strong positive correlation with Pseudomonas aeruginosa numbers. This demonstrated that short fluorescent labelled peptides can be used to detect protease activity in chronic wound fluid samples. The finding that two peptides were specific indicators for the presence of P. aeruginosa may be the basis for a diagnostic test to determine wound colonisation by this organism
Reduced Life- and Healthspan in Mice Carrying a Mono-Allelic BubR1 MVA Mutation
Mosaic Variegated Aneuploidy (MVA) syndrome is a rare autosomal recessive disorder characterized by inaccurate chromosome segregation and high rates of near-diploid aneuploidy. Children with MVA syndrome die at an early age, are cancer prone, and have progeroid features like facial dysmorphisms, short stature, and cataracts. The majority of MVA cases are linked to mutations in BUBR1, a mitotic checkpoint gene required for proper chromosome segregation. Affected patients either have bi-allelic BUBR1 mutations, with one allele harboring a missense mutation and the other a nonsense mutation, or mono-allelic BUBR1 mutations combined with allelic variants that yield low amounts of wild-type BubR1 protein. Parents of MVA patients that carry single allele mutations have mild mitotic defects, but whether they are at risk for any of the pathologies associated with MVA syndrome is unknown. To address this, we engineered a mouse model for the nonsense mutation 2211insGTTA (referred to as GTTA) found in MVA patients with bi-allelic BUBR1 mutations. Here we report that both the median and maximum lifespans of the resulting BubR1(+/GTTA) mice are significantly reduced. Furthermore, BubR1(+/GTTA) mice develop several aging-related phenotypes at an accelerated rate, including cataract formation, lordokyphosis, skeletal muscle wasting, impaired exercise ability, and fat loss. BubR1(+/GTTA) mice develop mild aneuploidies and show enhanced growth of carcinogen-induced tumors. Collectively, these data demonstrate that the BUBR1 GTTA mutation compromises longevity and healthspan, raising the interesting possibility that mono-allelic changes in BUBR1 might contribute to differences in aging rates in the general population
The Exomars Climate Sounder (EMCS) Investigation
The ExoMars Climate Sounder (EMCS) investigation is developed at the Jet Propulsion Laboratory (Principal Investigator J. T. Schofield) in collaboration with an international scientific team from France, the United Kingdom and the USA.
EMCS plans to map daily, global, pole-to-pole profiles of temperature, dust, water and CO2 ices, and water vapor from the proposed 2016 ExoMars Trace Gas Orbiter (EMTGO). These profiles are to be assimilated into Mars General Circulation Models (MGCMs) to generate global, interpolated fields of measured and derived parameters such as wind
The unstable coastline: navigating dispossession and belonging in Colombo
This article explores how residents of a small coastal fishing enclave in Colombo live with cumulative waves of dispossession brought on by exclusionary projects of urban development. Drawing on ethnographic fieldwork, I introduce the analytic of navigation to describe how people move, plan and live with both present and future threats of dispossession. Navigation offers a unique perspective on questions of agency and resistance in oppressive conditions. Rather than framing subjects as âresistingâ projects of world-class city-making, this analysis shows that urban residents instead engage in complex and occasionally contradictory modes of living with uncertainty. I complicate existing understandings of the term ânavigationâ by describing how questions of nation and belonging are crucial to comprehending how people navigate. Ultimately, I suggest that expressions of belonging and obligation to an imagined community might not only be strategic, but instead reflect some of the broader social forces which structure possibilities for action
Green synthesis of silver nanoparticles using <i>Atalantia monophylla</i>: A potential eco-friendly agent for controlling blood-sucking vectors
Abstract
Developing floral-based replacement molecules might manage blood-sucking vectors in an eco-friendly way. Atalantia monophylla (Am) aqueous leaf extract (ALE) and silver nanoparticles (AgNPs) were evaluated against mosquitoes (Aedes vittatus, Anopheles subpictus, and Culex vishnui) and ticks (Haemaphysalis bispinosa, Rhipicephalus microplus, and R. sanguineus) at different concentrations. Phytochemical screening and AgNPs' synthesis were performed on ALE of A. monophylla. UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscope, and transmission electron microscope were used to examine the synthesized Am-AgNPs. A. monophylla's ALE included alkaloids, flavonoids, saponins, tannins, triterpenes, coumarins, anthraquinones, and phenolics. Am-AgNPs had a higher LC50 (22.19, 23.92, 26.09, 40.25, 51.87, and 60.53âÎŒg·mLâ1, respectively) than leaf aqueous extract (LAE) against Ae. vittatus, An. subpictus, Cx. vishnui, H. bispinosa, R. microplus, and R. sanguineus larvae. A. monophylla ALE and Am-AgNPs' bio-toxicity was investigated against aquatic and terrestrial non-target species (Acilius sulcatus, Anisops bouvieri, Araneus mitificus, and Cyrtophora moluccensis) with LC50 values ranging from 2,094.5 to 10,532.8âÎŒg·mLâ1, respectively. A. monophylla ALE and Am-AgNPs had little negative impacts on the chosen non-target fauna. Environmental protection is important nowadays. Green AgNPs are low-cost, readily accessible, environmentally safe, and effective pesticides. Am-AgNPs are effective alternative insecticides, requiring a considerable study on this plant to control blood-sucking vectors for worldwide human/animal health importance
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