120 research outputs found

    Optimal response and covariate-adaptive biased-coin designs for clinical trials with continuous multivariate or longitudinal responses

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    Adaptive randomization of the sequential construction of optimum experimental designs is used to derive biased-coin designs for longitudinal clinical trials with continuous responses. The designs, coming from a very general rule, target pre-specified allocation proportions for the ranked treatment effects. Many of the properties of the designs are similar to those of well understood designs for univariate responses. A numerical study illustrates this similarity in a comparison of four designs for longitudinal trials. Designs for multivariate responses can likewise be found, requiring only the appropriate information matrix. Some new results in the theory of optimum experimental design for multivariate responses are presented

    An observational study to compare Muhtaseb's and Habib's scoring systems in patients undergoing phacoemulsification to predict risk in cataract at a tertiary centre in West Bengal

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    Background: Cataract is derived from the Latin ‘cataracta’, meaning ‘waterfall’ as rapidly running water turns white, so term may have been used metaphorically to describe similar appearance of mature ocular opacities.1 Methods: This observational study with prospective study design has been conducted in the college of medicine and JNM hospital, department of ophthalmology, COMJNMH, Kalyani-741235, Nadia District, West Bengal which catering mostly the rural and also urban population. The study was done spread over a period of 18 months starting from July 2018 to December 2019, i.e., 1 year for research and 6 months for analysis. It included all patients, irrespective of age, undergoing Phacoemulsification surgery for cataract admitted in our hospital fulfilling the laid criteria for the study. Results: The study consisted of total 147 cases in these 14 (9.52%) cases complicated with PCR, 10 (6.80%) striate keratopathy and 4 (2.72%) cases complicated with both PCR and striate keratopathy. Though sample size derived was 126 cases, 147 cases were studied during the research period of 1 year. Out of 10.89% cases of miscellaneous risk (ex: poor position of the eye/patient) risk factor, posterior capsule rupture (12.5%), striate keratopathy (12.5%), cases having both complication (00.0%) and total complicated cases (25%) which is 1.36%, 1.36%, 0% and 2.72% of total cases respectively. Out of 8.84% cases of unable to lie flat risk factor, posterior capsule rupture (15.38%), striate keratopathy (7.69%), and total complicated cases (23.07%) which is 1.36%, 0.68% and 2.04% of total cases respectively. Conclusions: The current study tries to validate two scoring systems to predict complications during phacoemulsification surgerylike risk of posterior capsule rupture and striate keratopathy and to predict the potential difficulty of a case

    Amending the anisotropy barrier and luminescence behavior of heterometallic trinuclear linear M-II-Ln(III)-M-II (Ln(III)=Gd, Tb, Dy; M-II=Mg/Zn) complexes by change from divalent paramagnetic to diamagnetic metal ions

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    The sequential reaction of a multisite coordinating compartmental ligand LH4 [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] with appropriate lanthanide salts followed by the addition of Mg(NO3)2·6H2O or Zn(NO3)2·6H2O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2Ln]3+ [Ln = Dy (1), Gd (2) and Tb (3)] and [Zn2Ln]3+ [Ln = Dy (4), Gd (5) and Tb (6)] cores. The formation of 1-6 is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. In this article we have discussed the comprehensive studies, involving synthesis, structure, magnetism and photophysical properties on this family of trinuclear [Mg2Ln]3+ and [Zn2Ln]3+ heterometallic complexes. Complexes 1 and 4 show slow relaxation of the magnetization below 12 K under zero applied direct-current field, but without reaching a neat maximum which is due to the overlapping with a faster quantum tunnelling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied direct-current field of 1000 Oe the quantum tunneling was almost suppressed and temperature and frequency dependent peaks were observed, thus confirming the SMM behavior of complexes 1 and 4. The fit of the high-temperature relaxation times to the Arrhenius equation affords an effective energy barrier for the reversal of the magnetization of Ueff =72(2) K with o = 8 x 10-9 s for the SR process and Ueff = 61(2) K with o = 4 x 10-7 s for the FR process for 1 whereas for 4, an effective energy barrier for the reversal of the magnetization Ueff = 67(3) K with o = 4.5 x 10-8 s. To rule out the involvement of intermolecular collaborative interactions in the dynamic of relaxation, we have performed ac susceptibility measurements on 1:10 Dy:Y magnetic diluted samples of of 1 and 4, named as 1' and 4'. Interestingly, the diluted compounds 1' and 4' exhibits SMM behavior under zero magnetic field, thus suggesting that their relaxation processes are single molecular in origin and arise from the M-Dy-M unit. Ab initio CASSCF+RASSI calculations carried out on 1 and 4 confirm that the magnetic anisotropy is axial along the M-Dy-M axis and that the relaxation process occurs through the first excited energy level. Furthermore, the chromophoric [LH3]2- ligand is able to act as an 'antenna' group which was found to be effective in the selective sensitization of the emissions of TbIII-based complexes 3 and 6. The emission quantum yields and the luminescence lifetimes at room temperature are 11.7 % and 0.606 ms for 3, 22.7 % and 0.799 ms for 6

    FILMES DE POLIANILINA (PANI) ELETROPOLIMERIZADOS SOBRE SUPERFÍCIE DE ITO PARA USO COMO INDICADOR COLORIMÉTRICO PARA DETECÇÃO DA AMÔNIA: POLIMERIZAÇÃO DE FILMES DE PANI COMO INDICADOR DA PRESENÇA DE AMÕNIA

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    Indicadores colorimétricos são sistemas que podem facilmente ser introduzidos a embalagens, a fim de informar ao consumidor a cerca da qualidade do produto. Amônia é gerada durante a deterioração do pescado e pode ser monitorada por meio de indicadores colorimétricos. Neste trabalho objetivou-se eletrossintetizar filmes de polianilina para a detecção da amônia por meio da mudança de cor. Filmes foram eletrodepositados por voltametria cíclica e cronoamperometria em meio ácido sobre superfície de ITO. O filme crescido por voltametria cíclica apresentou uma morfologia mais plana e um limite de detecção de 0,05 mol L-1. O filme crescido por cronoamperometria apresentou uma morfologia de rede interconectada, um limite de detecção de 0,015 mol L−1 e uma mudança de cor verde para azul mais perceptível visualmente. Assim, recomenda-se produzir o filme por cronoamperometria para a produção de um indicador colorimétrico para detecção da amônia em função do limite de detecção e da melhor visualização da mudança de coloração

    Molecular enneanuclear CuII phosphates containing planar hexanuclear and trinuclear sub-units: syntheses, structures, and magnetism

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    Highly symmetric enneanuclear copper(II) phosphates [Cu9(Pz)6(μ-OH)3(μ3-OH)(ArOPO3)4(DMF)3] (PzH =pyrazole, Ar = 2,6-(CHPh2)2-4-R-C6H2; R = Me, 2MeAr; Et, 2EtAr; iPr, 2iPrAr; and Ar = 2,6-iPr2C6H3, 2Dip) comprising nine copper(II) centers and pyrazole, hydroxide and DMF as ancillary ligands were synthesized by a reaction involving the arylphosphate monoester, 1, copper(I)chloride, pyrazole, and triethylamine in a 4 : 9 : 6 : 14 ratio. All four complexes were characterized by single crystal structural analysis. The complexes contain two distinct structural motifs within the multinuclear copper scaffold: a hexanuclear unit and a trinuclear unit. In the latter, the three Cu(II) centres are bridged by a µ3-OH. Each pair of Cu(II) centers in the trinuclear unit are bridged by a pyrazole ligand. The hexanuclear unit is made up of three dinuclear Cu(II) motifs where the two Cu(II) centres are bridged by an -OH and a pyrazole ligand. The three dinuclear units are connected to each other by phosphate ligands. The latter also aid the fusion of the trinuclear and the hexanuclear motifs. Magnetic studies reveal a strong antiferromagnetic exchange between the Cu(II) centres of the dinuclear units in the hexanuclear part and a strong spin frustration in the trinuclear part leading to a degenerate ground state

    Use of multidimensional item response theory methods for dementia prevalence prediction : an example using the Health and Retirement Survey and the Aging, Demographics, and Memory Study

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    Background Data sparsity is a major limitation to estimating national and global dementia burden. Surveys with full diagnostic evaluations of dementia prevalence are prohibitively resource-intensive in many settings. However, validation samples from nationally representative surveys allow for the development of algorithms for the prediction of dementia prevalence nationally. Methods Using cognitive testing data and data on functional limitations from Wave A (2001-2003) of the ADAMS study (n = 744) and the 2000 wave of the HRS study (n = 6358) we estimated a two-dimensional item response theory model to calculate cognition and function scores for all individuals over 70. Based on diagnostic information from the formal clinical adjudication in ADAMS, we fit a logistic regression model for the classification of dementia status using cognition and function scores and applied this algorithm to the full HRS sample to calculate dementia prevalence by age and sex. Results Our algorithm had a cross-validated predictive accuracy of 88% (86-90), and an area under the curve of 0.97 (0.97-0.98) in ADAMS. Prevalence was higher in females than males and increased over age, with a prevalence of 4% (3-4) in individuals 70-79, 11% (9-12) in individuals 80-89 years old, and 28% (22-35) in those 90 and older. Conclusions Our model had similar or better accuracy as compared to previously reviewed algorithms for the prediction of dementia prevalence in HRS, while utilizing more flexible methods. These methods could be more easily generalized and utilized to estimate dementia prevalence in other national surveys
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