76
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Jiang C, Yan B, Moutinho HR, Al-Jassim MM, Yang J, Guha S. Light Soaking and Thermal Annealing Effects on the Micro-Electrical Properties of Amorphous and Nanocrystalline Mixed-phase Silicon Solar Cells. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-0989-a02-05] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractWe report on the measurement of local current flow in hydrogenated amorphous and nanocrystalline mixed-phase n-i-p silicon solar cells in the initial, light-soaked, and annealed states using conductive atomic force microscopy (C-AFM). The C-AFM measurement shows that the nanometer-size grains aggregate, and the local current densities in the nanocrystalline aggregation areas decreased significantly after light soaking and recovered to values similar to the initial state after annealing at a high temperature in a vacuum. This result supports the model of two parallel-connected diodes for explaining the light-induced open-circuit voltage increase in the mixed-phase solar cells.
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77
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Zhu K, Yang J, Wang W, Schiff EA, Liang J, Guha S. Bandtail Limits to Solar Conversion Efficiencies in Amorphous Silicon Solar Cells. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-762-a3.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractWe describe a model for a-Si:H based pin solar cells derived primarily from valence bandtail properties. We show how hole drift-mobility measurements and measurements of the temperature-dependence of the open-circuit voltage VOC can be used to estimate the parameters, and we present VOC(T) measurements. We compared the power density under solar illumination calculated with this model with published results for as-deposited a-Si:H solar cells. The agreement is within 4% for a range of thicknesses, suggesting that the power from as-deposited cells is close to the bandtail limit.
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78
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Liang J, Schiff EA, Guha S, Yan B, Yang J. Light-Soaking Effects on the Open-Circuit Voltage of a-Si:H Solar Cells. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-862-a13.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractWe present measurements on the decline of the open-circuit voltage VOC in a-Si:H solar cells during extended illumination (light-soaking) at 295 K. We used a near-infrared laser that was nearly uniformly absorbed in the intrinsic layer of the cell. At the highest photogeneration rate (about 2x1021 cm-3), a noticeable decline (0.01 V) occurred within about 10 minutes; VOC stabilized at 0.04 V below its initial value after about 200 hours. We found that both the kinetics and the magnitudes of VOC are reasonably consistent with the predictions of a calculation combining a bandtail+defect picture for recombination and a hydrogen-collision model for defect generation. The version of the hydrogen-collision model that we used assumes that only bandtail recombination drives the hydrogen collision processes. Within this picture, the crossover between bandtail and defect recombination occurs on the same timescale as the “light-induced annealing” process that accounts for stabilization of the optoelectronic properties for long lightsoaking times.
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79
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Knaapila M, Stepanyan R, Haase D, Carlson S, Torkkeli M, Cerenius Y, Scherf U, Guha S. Evidence for structural transition in hairy-rod poly[9,9-bis(2-ethylhexyl)fluorene] under high pressure conditions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:051803. [PMID: 21230493 DOI: 10.1103/physreve.82.051803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Indexed: 05/30/2023]
Abstract
We report on an x-ray scattering experiment of bulk poly[9,9-bis(2-ethylhexyl)fluorene] under quasihydrostatic pressure from 1 to 11 GPa at room temperature. The scattering pattern of high molecular weight (HMW) polyfluorene (>10 kg/mol) undergoes significant changes between 2 and 4 GPa in the bulk phase. The 110 reflection of the hexagonal unit cell disappears, indicating a change in equatorial intermolecular order. The intensity of the 00 21 reflection drops, with a sudden move toward higher scattering angles. Beyond these pressures, the diminished 00 21 reflection tends to return toward lower angles. These changes may be interpreted as a transition from crystalline hexagonal to glassy nematic phase (perceiving order only in one direction). This transition may be rationalized by density arguments and the underlying theory of phase behavior of hairy-rod polyfluorene. Also the possible alteration of the 21-helical main chain toward more planar main chain conformation is discussed. The scattering of low molecular weight polyfluorene (<10 kg/mol) , which is glassy nematic in ambient pressure, is reminiscent with that of HMW polymer above 2-4 GPa.
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80
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Deorukhkar A, Ahuja N, Mercado A, Diagaradjane P, Mohindra P, Guha S, Aggarwal B, Krishnan S. Zerumbone, a Sesquiterpene from Southeast Asian Edible Ginger Sensitizes Colorectal Cancer Cells to Radiation Therapy. Int J Radiat Oncol Biol Phys 2010. [DOI: 10.1016/j.ijrobp.2010.07.1522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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81
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Varia AK, Guha S, Hassan M, Kaseb AO. A single multidisciplinary center's experience in the management of hepatitis C virus-induced hepatocellular carcinoma in 184 patients. J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.e14594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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82
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Gunasekharan MK, Guha S, Vani V, Gopal ESR. Effect of Interfacial Polarization on the Critical Behaviour of Electrical Resistivity and Dielectric Constant in Polar + Nonpolar Binary Liquid Mixtures. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19850891208] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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83
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Paudel K, Knoll H, Chandrasekhar M, Guha S. Tuning Intermolecular Interactions in Dioctyl-Substituted Polyfluorene via Hydrostatic Pressure. J Phys Chem A 2010; 114:4680-8. [DOI: 10.1021/jp911778r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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84
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Mukhopadhyay S, Ramasesha S, Guha S. Role of the triplet state in the green emission peak of polyfluorene films: A time evolution study. J Chem Phys 2010; 132:044104. [DOI: 10.1063/1.3298371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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85
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Horgan R, Guha S, O'sullivan K, Higgins JR. Ascertaining women's choice of title during pregnancy and childbirth. J OBSTET GYNAECOL 2009. [DOI: 10.1080/718591717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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86
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Yeo S, Guha S, Cheong SW. Generic properties of Mn spinels with an immiscibility induced by a Jahn-Teller distortion. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:125402. [PMID: 21817463 DOI: 10.1088/0953-8984/21/12/125402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The generic properties are scrutinized in Mn spinels with an immiscibility induced by a Jahn-Teller distortion through the CoFe(2-x)Mn(x)O(4) system. The x-ray diffraction experiment reveals that the immiscibility occurs at 1.1<x<2.0 and the relevant kinetics becomes faster with x. The temperature of the Jahn-Teller transition, which accompanies a sharp resistivity anomaly and matches the immiscibility gap boundary, increases with increasing x. The evolution of the magnetic and structural properties with various thermal treatments is studied carefully in this paper. Based on our comprehensive results, we have constructed a phase diagram of CoFe(2-x)Mn(x)O(4).
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87
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Guha S, Chakraborty R. Correlation analyses reveal a substantial influence of allelic gaps on the investigation of genetic diversity of modern human populations with microsatellites. Ann Hum Genet 2008; 72:644-53. [PMID: 18460049 DOI: 10.1111/j.1469-1809.2008.00445.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High intra-population genetic diversity and multiple measures of genetic variability at STR loci are useful in inferring past evolutionary history. However, STRs, categorized by their repeat motif size, differ in a number of aspects, requiring separate analyses. We analyzed 783 STRs in 36 worldwide populations to examine marker suitability as well as correlations between various measurements, to evaluate the extent of genomic diversity present in modern human populations. The loci were grouped by type and analyzed separately for each population group. Genetic variation defined by gene diversity and allele size variance, shows different trends of variation across four types of STRs. Additionally, there is little variation of genetic diversity, but there is decreased allelic size variance with increasing repeat motifs. A poor correlation between genetic diversity and allelic size variance across loci in all groups for Di-STRs is probably caused by the presence of allelic size gaps. In contrast, allelic size variance, genetic diversity, and number of alleles are strongly correlated with both tri- and tetra-STRs. The positive correlation of allelic size variance and presence of gaps within the range of allelic sizes in Di-STRs alone explains these observations. An unexpected high imbalance index (beta) at Di-STRs due to high allelic size variance also supports this assertion.
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88
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Enoch DA, Cooke FJ, Guha S, Brown NM. Thermostable nuclease: a study of clinical impact. J Antimicrob Chemother 2008; 61:754-5. [PMID: 18218643 DOI: 10.1093/jac/dkn003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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89
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Guha S, Roy Chowdhury R. Re: a long-term study of women with normal colposcopy after referral with low-grade cytological abnormalities. BJOG 2007; 114:508; author reply 508. [PMID: 17378824 DOI: 10.1111/j.1471-0528.2006.01253.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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90
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Volz C, Arif M, Guha S. Conformations in dioctyl substituted polyfluorene: A combined theoretical and experimental Raman scattering study. J Chem Phys 2007; 126:064905. [PMID: 17313242 DOI: 10.1063/1.2434976] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural properties of polyfluorenes (PF) are extremely sensitive to the choice of functionalizing side chains. Dioctyl substituted PF (PF8) adopts metastable structures that depend upon the thermal history and choice of solvents used in film forming conditions. We present a detailed study of the changes in the backbone and side chain morphology in PF8, induced by the various crystallographic phases, using Raman scattering techniques. The vibrational frequencies and intensities of fluorene oligomers are calculated using hybrid density-functional theory with a 3-21G(*) basis set. The alkyl side chains are modeled as limiting conformations: all anti, anti-gauche-gauche, and end gauche representations. The calculated vibrational spectra of single chain oligomers in conjunction with our experimental results demonstrate the beta phase, which is known to originate in regions of enhanced chain planarity as a direct consequence of the alkyl side chain conformation.
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91
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Morrow D, Sweeney C, Guha S, Walshe T, O'Brien C, Walls D, Redmond EM, Cahill PA. Notch signaling and vascular cell fate--how vascular cells respond to stress. Wien Klin Wochenschr 2007; 119:7-10. [PMID: 19618589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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92
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Priebe W, Fokt I, Szymanski S, Bao Y, Conrad C, Chakraborty A, Abbruzzese J, Guha S, Myers J, Madden T. 556 POSTER Novel small molecule inhibitors of Jak2/STAT3 pathway: design, structurte-activity relationship, and oral bioavilability. EJC Suppl 2006. [DOI: 10.1016/s1359-6349(06)70561-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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93
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Guha S, Lorentzen J, Sinha K, Menéndez J, Adams GB, Page JB, Sankey OF. Extrinsic Nature of the 2.5 eV Raman Resonance in C60. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259408039268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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94
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Guha S, Goyal SP, Kashyap VK. Genomic variation in the mitochondrially encoded cytochrome b (MT-CYB) and 16S rRNA (MT-RNR2) genes: characterization of eight endangered Pecoran species. Anim Genet 2006; 37:262-5. [PMID: 16734688 DOI: 10.1111/j.1365-2052.2006.01421.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In an effort to develop species-specific identification markers, we examined genetic variants and molecular signatures within genes encoding mitochondrial cytochrome b and 16S rRNA in eight endangered Pecoran species endemic to the Indian peninsula. Our results revealed that the cytochrome b gene exhibited higher sequence diversity than the 16S rRNA gene, both between and within species. However, the 16S rRNA gene harboured a larger number of species-specific mutation sites compared with the cytochrome b gene, suggesting that it could be useful for species identification. Indeed, we successfully used 'forensically informative nucleotide sequencing' (FINS) analysis of the 16S rRNA gene to identify two previously unknown biological specimens.
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95
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Guha S, Mukherjee AK, Maji TK, Ray Chaudhuri N. Synthesis and X-ray structure of two conformational isomers of [Zn(medpt)(SCN)2], medpt = bis (3 – aminopropyl)methylamine. CRYSTAL RESEARCH AND TECHNOLOGY 2006. [DOI: 10.1002/crat.200510555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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96
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Arif M, Volz C, Guha S. Chain morphologies in semicrystalline polyfluorene: evidence from Raman scattering. PHYSICAL REVIEW LETTERS 2006; 96:025503. [PMID: 16486593 DOI: 10.1103/physrevlett.96.025503] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Indexed: 05/06/2023]
Abstract
The beta phase in di-octyl substituted polyfluorene (PF8) exhibits a surprising level of conformational order at nanometer length scales compared to other phases. We present Raman scattering studies of PF8 as a function of thermal cycling, which establishes a connection between the conformational isomers and the side and main chain morphology. Density-functional calculations of the vibrational spectra of single chain oligomers in conjunction with the experimental results demonstrate the incompatibility of the beta phase with the overall alpha crystalline phase in PF8.
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97
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Guha S, Pal SK, Chatterjee N, Sarkar G, Pal S, Guha S, Basu AK, Banerjee R. Effect of chitosan on lipid levels when administered concurrently with atorvastatin--a placebo controlled study. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 2005; 103:418, 420. [PMID: 16363196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In a placebo controlled trialthe lipid lowering effects of chitosan, a unique dietary fibre, was assessed when given along with atorvastatin 10 mg in patients with chronic coronary heart disease. Altogether 100 patients were studied. They were randomly allocated in two groups of 50 patients each. Patients of group A received atorvastatin 10 mg before dinner plus 2 g/day chitosan in two divided doses. The groupB patients received atorvastatin 10 mg plus placebo. Patients were followed up for a period of 6 weeks. There was significant reduction in mean body weight in group A patients (3.14% versus 1,29% of body weight, p<0.05). There was also a significant rise in HDL cholesterol value (3.8% versus 1.07%, p=0.02) in group A patients. However, there was no significant reduction in the mean values of total cholesterol, LDL cholesterol and triglyceride in the two groups, although group A patients showed marginally lower values.
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98
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Chattopadhyay P, Guha S. RAPD & FINS (mitochondrial 16s rRNA gene sequence) in analysis of food contamination: detection of food poisoning by Lizard. ACTA ACUST UNITED AC 2005; 12:74-80. [PMID: 15863021 DOI: 10.1016/j.jcfm.2004.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In poisoning, detection of the nature of causative agent is important for management of trauma and forensic investigation. Most of the methods in clinical toxicology are developed for detection of toxins and poisons. A random amplified polymorphic DNA (RAPD)-based method has been described for detection of species of animal from its morphologically unrecognizable fragments, recovered from food substances, consumption of which caused even death. Pre-mixed RAPD reaction beads and six RAPD primers were used in polymerase chain reaction analysis. Among six RAPD primers used, any one of them was sufficient in resolving this practical forensic situation. To enhance the probability values for matching in the present study of fixing identity of an animal, six set of market available RAPD primers were used. This is the first report of a forensic application of RAPD DNA typing in identification of charred skeleton remnants of Lizard species in food material. Furthermore unique amplicons were generated for different reptilian species, which can be used as species specific markers for species identification in forensic situation, however, no variations among individuals of same species were observed.
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Basu AK, Pal SK, Guha S, Banerjee R, Chatterjee N, Bag AK, Adhikary A. Carotid intima media thickness: an independent marker for assessment of macrovascular risk in diabetic patients. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 2005; 103:234-6. [PMID: 16173433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In view of the global epidemic of diabetes with India being the hottest reservoir of the disease, it was tried to identify carotid intima media thickness as a surrogate marker for atherosclerosis in diabetic subjects. The study becomes more relevant because diabetes is now considered a disease of the endothelium and a risk equivalent of coronary atherosclerosis (paradigm shift). The study incorporated 41 normotensive patients of diabetes and 31 age and sex matched controls. Plasma glucose and lipid profiles were assessed in all and the carotid intima media thickness was measured. Results were statistically analysed for significance and correlation coefficient between values of plasma glucose and carotid intima media thickness. Results clearly showed that carotid intima media thickness abnormality can pick up atherosclerosis even if the lipid parameters are nearly normal. So it crystallises from this small study that, as a non-invasive test carotid intima media thickness is a better and early predictor of atherosclerosis in diabetic subjects. It also revealed the linear relationship between both fasting and postprandial blood sugar with carotid intima media thickness.
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100
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Horgan R, Guha S, Sullivan KO, Higgins JR. Ascertaining women's preferred mode of address and preferred choice of title during pregnancy and childbirth. IRISH MEDICAL JOURNAL 2005; 98:55-7. [PMID: 15835514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
To determine how women in pregnancy would like to be addressed and to ascertain their preferred choice of title during pregnancy. A questionnaire was administered to 925 antenatal women. Midwifery and medical staff (183) were invited to respond to a similar questionnaire. The response rate was 71.2% from the survey of pregnant women. The vast majority (82.1%) preferred to be addressed by their first name. Women were in favour of being called 'patient' (32.8%) as their first choice. The staff survey yielded a response rate of 77%. The majority (81.8%) of health professionals preferred to address women by their first name. 'Mother' (28.7%) was the most popular first choice. We conclude that women in pregnancy do have a preference on how they would like to be addressed and this is predominantly by first name. Health professionals also prefer to call pregnant women by their first name. The term 'patient' was the most popular first choice of title of women in pregnancy but the term 'mother' was the preferred choice of the health professionals. Medical staff were more likely to choose 'patient' than midwives.
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