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Guha S, Pal SK, Chatterjee N, Guha S, Ghosh A, Deb PK. How predictive is the Framingham's risk prediction algorithm in Indian perspective? A retrospective case-control study from Kolkata. Indian Heart J 2008; 60:330-332. [PMID: 19242011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
OBJECTIVE In this retrospective case-control study, an attempt was made to assess the predictive efficacy of Framingham's risk prediction algorithm in Indian perspective. METHODS A total of 350 patients and 293 age- and sex-matched controls were considered in the study. Those patients, who were presenting for the first time with acute coronary syndrome (ACS) and who did not have any prior manifestation of coronary heart disease (CHD) formed the patient group. The risk prediction algorithm was applied to obtain the risk score and the corresponding 10-year risk in each patient and control. They were divided into two groups: diabetic and nondiabetic. Depending on the 10-year risk, they were further grouped into high risk (10-year risk > 20%), moderately high risk (10-year risk between 10% to 20%), and low risk (10-year risk < 10%). The results were compared and statistically analyzed. RESULTS In the diabetic patients with ACS, 14.29% qualified as high risk, 32.79% as moderately high risk, and 52.94% as low risk. The corresponding figures for diabetic subjects without ACS were 3.26%, 54.35%, and 42.39%, respectively. In nondiabetic patients with ACS, 19.91% were in the high-risk group, 38.96% in moderately high risk, and 41.13% in the low-risk group; while among the controls, the corresponding figures were 9.95%, 21.89%, and 68.16%, respectively. In nondiabetic subjects, the mean risk was significantly higher for patients compared to controls (14.13 vs. 8.61, p < 0.01). However, in diabetic subjects, there was no significant difference in the mean projected risk between those with ACS and those without ACS (11.37 vs. 10.41, p = NS). CONCLUSION In the Indian perspective, Framingham's risk prediction protocol has a fair amount of predictive efficacy since the difference of mean risk score between the patients and controls was statistically significant. However, it fails to identify a large proportion of high-risk nondiabetic patients. Hence, a better protocol for the Indian perspective is badly needed.
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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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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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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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80
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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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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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82
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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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83
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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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84
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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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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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86
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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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Guha S, Ghosh A, Chatterjee N, Pal S, Guha S, Chatterjee S, Deb PK, Dawn B. Risk factors for coronary heart disease in Indians: a case-control study from Eastern India. Indian Heart J 2005; 57:738-40. [PMID: 16521652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
We conducted a hospital-based case-control investigation (150 cases and 176 controls) to examine the putative role of conventional risk factors in subjects with and without coronary heart disease from Eastern India. Multivariate binary logistic regression revealed the following as significant risk factors for coronary heart disease: male sex (OR = 4.6, p = 0.001), elevated total cholesterol/high-density lipoprotein ratio (OR = 4.0, p = 0.001), systolic blood pressure (OR = 3.0, p = 0.004), diastolic blood pressure (OR = 3.6, p = 0.002), fasting plasma glucose (OR = 3.0, p = 0.05), post-pondrial plasma glucose (OR = 3.2, p = 0.005), Impaired fasting glucose (OR = 3.7, p = 0.002), elevated triglyceride (OR = 3.1, p = 0.018), increased total cholesterol (OR = 3.0, p = 0.029), low-density lipoprotein (OR = 3.1, p = 0.001), low-density lipoprotein/high-density lipoprotein ratio (OR = 3.4, p = 0.004), central obesity (OR = 3.0, p = 0.006), smoking (OR = 3.7, p = 0.001) and urban residence (OR = 3.1, p = 0.003). In this study, the discriminant analysis showed that 77.2% of all entry for cases and 72.6% of all entry for controls were correctly classified using conventional risk factors and warrant early intervention for conventional risk factors.
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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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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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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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Tanto B, Guha S, Martin CM, Scherf U, Winokur MJ. Structural and Spectroscopic Investigations of Bulk Poly[bis(2-ethyl)hexylfluorene]. Macromolecules 2004. [DOI: 10.1021/ma049006p] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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93
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Sharma PA, Ahn JS, Hur N, Park S, Kim SB, Lee S, Park JG, Guha S, Cheong SW. Thermal conductivity of geometrically frustrated, ferroelectric YMnO3: extraordinary spin-phonon interactions. PHYSICAL REVIEW LETTERS 2004; 93:177202. [PMID: 15525119 DOI: 10.1103/physrevlett.93.177202] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2003] [Indexed: 05/24/2023]
Abstract
The thermal conductivity of the magnetically frustrated, ferroelectric YMnO3 exhibits an isotropic suppression in the cooperative paramagnetic state, followed by a sudden increase upon magnetic ordering. This unprecedented behavior without an associated static structural distortion probably originates from the strong dynamic coupling between acoustic phonons and low-energy spin fluctuations in geometrically frustrated magnets. The replacement of magnetic Ho for Y at the ferroelectrically active site results in an even larger effect, suggestive of the strong influence of multiferroicity.
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Guha S, Basu AK, Pal SK, Chatterjee N, Guha S, Deb PK. Predictive efficacy of Framingham's risk score in Indian scenario--a retrospective case-control study. JOURNAL OF THE INDIAN MEDICAL ASSOCIATION 2004; 102:568, 570, 584 passim. [PMID: 15887826] [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 assess the predictive ability of Framingham's risk score in primary prevention in our population, 252 cases and 212 age and sex matched controls were taken up for study. Those patients, who were presenting for the first time with acute coronarysyndrome (ACS) and who did not have any prior manifestations of coronary artery disease (CAD) and whose medical records were available formed the patient group. Framingham's risk score was calculated and the corresponding 10 years risk was assessed in each of them. The patients and controls were divided into two groups--diabetic and non-diabetic. Depending on the 10 years risk, they were further grouped into high risk (10 years risk > 20%), moderately high risk (10 years risk 10 to 20%) and low risk (10 years risk less than 10%). Results were compared and statistically analysed. In the diabetic patients with ACS 14% would have qualified as high risk, 33% as moderately high risk and 53% as low risk whereas in diabetic patients without any manifestation of CAD the distribution was 4% in the high risk, 54% in the moderately high risk and 42% in the low risk. In the non-diabetic subjects, amongst the patients of ACS, 20% would have been in high risk, 39% in moderately high risk and 41% in the low risk. The corresponding figures in the non-diabetic control subjects were 10% in high risk, 22% in the moderately high risk and 68% in the low risk. In the non-diabetic subjects, the mean risk was significantly more in patients than in controls (14.15% versus 8.61%, p <0.01). However, in the diabetic patients there was no significant difference in the mean projected risk between patients with ACS and patients without any manifestation of CAD (11.37% versus 10.41%, p>0.05).
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Hur N, Park S, Sharma PA, Guha S, Cheong SW. Colossal magnetodielectric effects in DyMn2O5. PHYSICAL REVIEW LETTERS 2004; 93:107207. [PMID: 15447448 DOI: 10.1103/physrevlett.93.107207] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Indexed: 05/24/2023]
Abstract
We have investigated the detailed magnetic field dependence of the electric polarization and dielectric constant in (Tb,Dy,Ho)Mn2O5 where magnetic and ferroelectric transitions are intimately coupled. Our fundamental discovery is the unprecedented large change of the dielectric constant with magnetic field, particularly in DyMn2O5, associated with an unusual commensurate-incommensurate magnetic transition. This extraordinary effect appears to originate from the high sensitivity of the incommensurate state to external perturbation.
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Cieplak MZ, Malinowski A, Guha S, Berkowski M. Localization and interaction effects in strongly underdoped La2-xSrxCuO4. PHYSICAL REVIEW LETTERS 2004; 92:187003. [PMID: 15169526 DOI: 10.1103/physrevlett.92.187003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2003] [Revised: 01/08/2004] [Indexed: 05/24/2023]
Abstract
The in-plane magnetoresistance (MR) in La(2-x)SrxCuO4 films with 0.03< x <0.05 has been studied in the temperature range 1.6 to 100 K, and in magnetic fields up to 14 T, parallel and perpendicular to the CuO2 planes. The behavior of the MR is consistent with a predominant influence of interaction effects at high temperatures, switching gradually to a regime dominated by spin scattering at low T. Weak localization effects are absent. A positive orbital MR appears close to the boundary between the antiferromagnetic and the spin-glass phase, suggesting the onset of Maki-Thompson superconducting fluctuations deep inside the insulating phase.
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Hur N, Park S, Sharma PA, Ahn JS, Guha S, Cheong SW. Electric polarization reversal and memory in a multiferroic material induced by magnetic fields. Nature 2004; 429:392-5. [PMID: 15164057 DOI: 10.1038/nature02572] [Citation(s) in RCA: 416] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 04/19/2004] [Indexed: 11/09/2022]
Abstract
Ferroelectric and magnetic materials are a time-honoured subject of study and have led to some of the most important technological advances to date. Magnetism and ferroelectricity are involved with local spins and off-centre structural distortions, respectively. These two seemingly unrelated phenomena can coexist in certain unusual materials, termed multiferroics. Despite the possible coexistence of ferroelectricity and magnetism, a pronounced interplay between these properties has rarely been observed. This has prevented the realization of multiferroic devices offering such functionality. Here, we report a striking interplay between ferroelectricity and magnetism in the multiferroic TbMn2O5, demonstrated by a highly reproducible electric polarization reversal and permanent polarization imprint that are both actuated by an applied magnetic field. Our results point to new device applications such as magnetically recorded ferroelectric memory.
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Park S, Hur N, Guha S, Cheong SW. Percolative conduction in the half-metallic-ferromagnetic and ferroelectric mixture of (La, Lu, Sr)MnO3. PHYSICAL REVIEW LETTERS 2004; 92:167206. [PMID: 15169259 DOI: 10.1103/physrevlett.92.167206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2003] [Indexed: 05/24/2023]
Abstract
The immiscibility between rhombohedral La(5/8)Sr(3/8)MnO3 and hexagonal LuMnO3 leads to a microm-scale heterogeneous mixture of half-metallic-ferromagnetic and insulating-ferroelectric phases. Electronic conduction of the mixture exhibits nearly ideal percolation behavior in the paramagnetic state with a threshold of 0.224(5) metal volume fraction and a resistivity scaling exponent t=2.1+/-0.1, consistent with the predicted universal behavior of classical percolation. However, far below T(C), t increases to 2.4+/-0.1, probably resulting from intergrain tunneling. Therefore, this system represents a unique example of the temperature-induced crossover from universal to nonuniversal behavior of t.
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Giovannetti V, Guha S, Lloyd S, Maccone L, Shapiro JH, Yuen HP. Classical capacity of the lossy bosonic channel: the exact solution. PHYSICAL REVIEW LETTERS 2004; 92:027902. [PMID: 14753969 DOI: 10.1103/physrevlett.92.027902] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Indexed: 05/24/2023]
Abstract
The classical capacity of the lossy bosonic channel is calculated exactly. It is shown that its Holevo information is not superadditive, and that a coherent-state encoding achieves capacity. The capacity of far-field, free-space optical communications is given as an example.
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Tiwari MK, Guha S, Harendranath CS. Enhanced granulation in UASB reactor treating low-strength wastewater by natural polymers. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2004; 50:235-240. [PMID: 15537012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Reetha (Sapindus trifoliata) seed extract and Chitosan were used as additives in the sludge bed of a UASB reactor treating low strength wastewater to enhance granulation. Five parallel laboratory scale UASB reactors were operated for 250 days with synthetic wastewater feed containing COD in the range of 600-800 mg/L. The reactors were seeded with spent sludge from a full-scale 5MLD UASB treatment plant at Jajmau, Kanpur, India. The seed sludge contained little or no granules. Different additives in the five reactors were as follows: control with no additive, cationic part of Reetha extract as additive, anionic part of Reetha extract as additive, bulk Reetha extract as additive and Chitosan as additive. The granulation rapidly increased in all the reactors beyond the 90th day of operation. The mean granule sizes as well as the fraction of granular sludge (particle size > or = 100 microm) were more in the presence of some of the additives compared to the control reactor. Chitosan significantly enhanced granulation followed by the cationic and anionic fractions of the Reetha extract. The bulk Reetha extract did not show enhancement of granulation. The ESEM/EDAX results showed that the bigger granules (3-4 mm) had porous structure and appeared as conglomerates of smaller granules.
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