Accelerating Asymptotically Exact MCMC for Computationally Intensive Models via Local Approximations

We construct a new framework for accelerating Markov chain Monte Carlo in posterior sampling problems where standard methods are limited by the computational cost of the likelihood, or of numerical models embedded therein. Our approach introduces local approximations of these models into the Metropolis-Hastings kernel, borrowing ideas from deterministic approximation theory, optimization, and experimental design. Previous efforts at integrating approximate models into inference typically sacrifice either the sampler's exactness or efficiency; our work seeks to address these limitations by exploiting useful convergence characteristics of local approximations. We prove the ergodicity of our approximate Markov chain, showing that it samples asymptotically from the \emph{exact} posterior distribution of interest. We describe variations of the algorithm that employ either local polynomial approximations or local Gaussian process regressors. Our theoretical results reinforce the key observation underlying this paper: when the likelihood has some \emph{local} regularity, the number of model evaluations per MCMC step can be greatly reduced without biasing the Monte Carlo average. Numerical experiments demonstrate multiple order-of-magnitude reductions in the number of forward model evaluations used in representative ODE and PDE inference problems, with both synthetic and real data.Comment: A major update of the theory and example

Cloudlet-based just-in-time indexing of IoT video

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Symptomatic treatment of children with anti-NMDAR encephalitis.

Abstract AIM: We performed the first study on the perceived benefit and adverse effects of symptomatic management in children with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. METHOD: A retrospective chart review was undertaken at two tertiary paediatric hospitals in Australia and New Zealand. We included 27 children (12 males, 15 females; mean age at admission 7y 1mo) with anti-NMDAR antibodies in serum or cerebrospinal fluid with a typical clinical syndrome. RESULTS: Only two out of 27 patients were white, whereas 16 out of 27 patients were from the Pacific Islands/New Zealand Maori. The mean duration of admission was 69 days (10-224d) and 48% of patients (13/27) needed treatment in an intensive care setting. A mean of eight medications per patient was used for symptomatic management. Symptoms treated were agitation (n=25), seizures (n=24), movement disorders (n=23), sleep disruption (n=17), psychiatric symptoms (n=10), and dysautonomia (n=four). The medications used included five different benzodiazepines (n=25), seven anticonvulsants (n=25), eight sedatives and sleep medications (n=23), five antipsychotics (n=12), and five medications for movement disorders (n=10). Sedative and sleep medications other than benzodiazepines were the most effective, with a mean benefit of 67.4% per medication and a mean adverse effect-benefit ratio of 0.04 per medication. Antipsychotic drugs were used for a short duration (median 9d), and had the poorest mean benefit per medication of 35.4% and an adverse effect-benefit ratio of 2.0 per medication. INTERPRETATION: Long-acting benzodiazepines, anticonvulsants, and clonidine can treat multiple symptoms. Patients with anti-NMDAR encephalitis appear vulnerable to antipsychotic-related adverse effects. Pacific Islanders appear to have a vulnerability to anti-NMDAR encephalitis in our region

Ferromagnetic Ga₁ˍₓ Mnₓ As produced by ion implantation and pulsed-laser melting

We demonstrate the formation of ferromagneticGa₁ˍₓMnₓAsfilms by Mn ion implantation into GaAs followed by pulsed-laser melting. Irradiation with a single excimer laser pulse results in the epitaxial regrowth of the implanted layer with Mn substitutional fraction up to 80% and effective Curie temperature up to 29 K for samples with a maximum Mn concentration of x≈0.03. A remanent magnetization persisting above 85 K has been observed for samples with x≈0.10, in which 40% of the Mn resides on substitutional lattice sites. We find that the ferromagnetism in Ga₁ˍₓMnₓAs is rather robust to the presence of structural defects.The work at the Lawrence Berkeley National Laboratory was supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. The work at Harvard was supported by NASA Grant No. NAG8-1680. One of the authors ~M.A.S.! acknowledges support from an NSF Graduate Research Fellowship

Probing the initial conditions of high-mass star formation -- IV. Gas dynamics and NH2_2D chemistry in high-mass precluster and protocluster clumps

The initial stage of star formation is a complex area study because of its high density and low temperature. Under such conditions, many molecules become depleted from the gas phase by freezing out onto dust grains. However, the deuterated species could remain gaseous and are thus ideal tracers. We investigate the gas dynamics and NH$_2$D chemistry in eight massive pre/protocluster clumps. We present NH$_2$D 1$_{11}$-1$_{01}$ (at 85.926 GHz), NH$_3$ (1, 1) and (2, 2) observations in the eight clumps using the PdBI and the VLA, respectively. We find that the distribution between deuterium fractionation and kinetic temperature shows a number density peak at around $T_{\rm kin}=16.1$ K, and the NH$_2$D cores are mainly located at a temperature range of 13.0 to 22.0 K. We detect seven instances of extremely high deuterium fractionation of $1.0 \leqslant D_{\rm frac} \leqslant 1.41$. We find that the NH$_2$D emission does not appear to coincide exactly with either dust continuum or NH$_3$ peak positions, but often surrounds the star-formation active regions. This suggests that the NH$_{2}$D has been destroyed by the central young stellar object (YSO) due to its heating. The detected NH$_2$D lines are very narrow with a median width of $\rm 0.98\pm0.02 km/s$. The extracted NH$_2$D cores are gravitationally bound ($\alpha_{\rm vir} < 1$), are likely prestellar or starless, and can potentially form intermediate-mass or high-mass stars. Using NH$_3$ (1, 1) as a dynamical tracer, we find very complicated dynamical movement, which can be explained by a combined process with outflow, rotation, convergent flow, collision, large velocity gradient, and rotating toroids. High deuterium fractionation strongly depends on the temperature condition. NH$_2$D is a poor evolutionary indicator of high-mass star formation in evolved stages, but a useful tracer in the starless and prestellar cores.Comment: 27 pages, 25 figures, 6 tables, accepted for publication in A&

Lung Cancer and Human Papilloma Viruses (HPVs): Examining the Molecular Evidence

Human papilloma virus (HPV), known to be an etiological agent for genital cancers, has been suggested also to be a possible contributory agent for lung cancer. Alternatively, lung cancer, formerly considered to be solely a smoker's disease, may now be more appropriately categorised into never smoker's and smoker's lung cancer. Through this paper we attempt to bring forth the current knowledge regarding mechanisms of HPV gaining access into the lung tissue, various strategies involved in HPV-associated tumorigenesis in lung tissue

Studies on the chemical quality of cured fish products from the west coast of India

Fish curing is one of the oldest industries of the coastal areas of India. It has been estimated that about 50 to 70% of the marine fish catches of India are at present being processed into cured products {Government of India Publication, 1951 a and b). Though fish curing is of this magnitude, it is one of the least developed industries of India, although efforts are being made in some of the maritime States such as Madras, Travancore-Cochin and Bombay, to improve curing by providing better facilities to the fishermen engaged in the industry. The methods practised are generally primitive and the attention paid to cleanliness and sanitation leaves much to be desired. Only 17-3% of the total fish landing is being cured through the Government fish curing yards {Government of India Marketing Report, 1951), the rest being processed in private yards which are not under the supervision of Government agencies

Ballistic evaluationof LOVA propellant in high calibre gun

'This paper presents the data obrained on dynamic firing of a cellulose acetate binder-based low vulnerability ammunition (LOV A) propellant using 120 mm fin-stabilised armour piercing discarding sabot (FSAPDS) kinetic energyammunition. An optimised propellant composition formulated ~sing fine RDX as an energetic ingredient and a mixture of cellulose acetate and nitrocellulose as binder was qualified fit for firing in a high calibre gun by its successful static evaluation for absolute ballistics using high pressure closed vessel technique. Dynamic firing of the propellant processed in heptatubular geometry was undertaken to assess the propellant charge mass. This propellant achieved higher muzzle velocity as compared to the standard NQ/M119 triple-base propellant while meeting the non-vulnerability characteristics convincingly

Characterization of New Bacterial Leaf Blight of Rice Caused by Pantoea stewartii subsp. indologenes in Southern Districts of Tamil Nadu

A survey was conducted in the rice fields of Tirunelveli, Tuticorin, Kanyakumari and Madurai districts of Tamil Nadu during 2016to assess the importance of bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv. oryzae. Bacterial Leaf Blight affected leaf samples showing yellowing symptoms or orange to brown stripes on one or both halves of the leaf blade were collected from seventeen places and maintained as isolates. Upon isolation, symptomatic leaf pieces were surface sterilized and placed in wakimoto semi-synthetic medium. The yellow pigmented, raised and translucent colonies with smooth margin were obtained after incubation at 28°C for 2 days. The biochemical characterization revealed that the bacteria belong to gramnegativefacultative anaerobes with small rods either arranged singly or in chains. Thirteen isolates show positive results in biochemical tests viz.,Gram staining, KOH test, starch hydrolysis, anaerobic growth test, tween 80 hydrolysis test, catalase test, citrate utilizationtest and production of yellow pigment on Yeast Dextrose Chalk agar medium. In virulence test, Isolate 1, Isolate 3 and Isolate 4 were considered virulent as they have caused severe blight symptoms both in TN1 and ADT 43, the susceptible check varieties. Based on 16S rRNA sequence analysis, the causal agent was identified as Pantoea stewartii subsp. indolegenes (Accession No. SUB2733370: MF163273; MF163274; MF16327). The biochemical and molecular analysis revealed that the causal agent was not Xanthomonas oryzae pv oryzae, but a new species of bacteriumnamely Pantoea stewartii subsp. indolegenes. This is the first report of new bacterial leaf blight disease of rice caused by Pantoea stewartii subsp.indologenesin southern districts of Tamil Nadu

Light Metal Matrix Composites - Present Status & Future Strategies

The unique tailorability of the composites to meet the required properties has made them as advanced engineering materials . The continuous fibre reinforced metal matrix composites were developed first . The high cost of the fibre as well as fabrication made them very expensive and hence they are used only in selected critical areas of aerospace and defence . The invention of synthesising discontinuous reinforced metal matrix composites by stir casting initiated in India in the early seventies 1 s a landmark in the history of Metal Matrix Composites (MMC). The initial feasibility studies on making the composites with variety of dispersoids for tailoring new materials possessing special properties with lower cost had kindled interest in many R&D and academic institutions in India in the eighties . Extensive R&D activities were witnessed during this period . The work carried out during this period can broadly be classified into processing methods . structure property correlation , specific property evaluation , prototype component development and evaluation , etc. The expected impact of composite as an exciting engineering material did not take place in the nineties.The industries are still not receptive and their response is lukewann . At present,only selective academic and R&D Institutions in India are pursuing MMC activity on a low profile . Eventhough similar trends in R&D were observed abroad in the developed countries wherein the industrial applications of composites specially in automotive and engineering industries is steadily increasing Indian industries are yet to think of using MMC components . This calls for a renewed concerted and sustaining effort,pooling up the resources and knowledge as well as consortium type approach among Indian R&D and Academic Institutions . The identified areas include generation of data bank on MMC and their properties. pilot plant production facility for demonstration of prototype developments under simulated industrial conditions , bringing down the cost by redesigning the components, etc