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  • 1
    Electronic Resource
    Electronic Resource
    57Fe Mössbauer spectroscopic investigation of complex magnetic structures in Ga, Sc, and In substituted M-type hexagonal ferrites (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5229-5230 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Investigation of preliminary evidence that Ga, Sc, and In influence the bulk and dynamic magnetic properties of hexagonal ferrites by means other than those supported in existing models has been undertaken. In SrFe12−xMxO19 (M=Ga, In) and BaFe12−xScxO19, the predominant 12k sublattice exhibits a remarkable splitting into two distinct subpatterns, 12k1 and 12k2: At x=0.3, hyperfine fields, Heff for 12k1 are 411, 408, and 405 kOe, respectively, and for 12k2 are 358, 339, and 311 kOe, respectively. The 12k1 hyperfine field values are virtually unchanged from that of the pure hexagonal ferrites and are independent of substitution level. Contrastingly, the abruptness of the drop in the 12k2 hyperfine field and its dependence on the nature of the substituting cation are remarkable. The relative intensity of the 12k2 component correlates with the concentration of nonmagnetic species on the 2b and 4f2 sites and with the magnetic anisotropy. Scandium seems to have a more profound influence on the magnetic structure and interactions than indium or gallium. Further, at technically significant substitution levels, Heff of the different sublattices exhibit broad and overlapping distributions of values far removed from their distinctiveness in the pure hexaferrites. Thus, the net magnetization of Ga, Sc, and In-doped hexaferrites results from a complex interplay of magnetic dilution on the 2b site, enhancement of the magnetization through substitutions on the 4f2 site, and a complex influence from the substitution-induced 12k2 sublattice. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369952
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric apertures as intracavity lenses in vertical-cavity lasers (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 313-315 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dielectric current apertures are shown to be effective as intracavity lenses for reduced optical losses in vertical-cavity lasers. The Gaussian resonator theory is applied to obtain a mode radius, and this is shown to be in good agreement with experiment as well as a recently proposed uniform waveguide model. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116070
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  • 3
    Electronic Resource
    Electronic Resource
    The Inverse Problem of the Calculus of Variations: Separable Systems (1999)
    Springer
    Acta applicandae mathematicae 57 (1999), S. 239-254 
    Details
    ISSN: 1572-9036
    Keywords: Lagrangian systems ; inverse problem ; integrability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper deals with the inverse problem of the calculus of variations for systems of second-order ordinary differential equations. The case of the problem which Douglas, in his classification of pairs of such equations, called the ‘separated case’ is generalized to arbitrary dimension. After identifying the conditions which should specify such a case for n equations in a coordinate-free way, two proofs of its variationality are presented. The first one follows the line of approach introduced by some of the authors in previous work, and is close in spirit, though being coordinate independent, to the Riquier analysis applied by Douglas for n = 2. The second proof is more direct and leads to the discovery that belonging to the ‘separated case’ has an intrinsic meaning for the given second-order differential equations: the system is separable in the sense that it can be decoupled into n pairs of first-order equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006238108507
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  • 4
    Electronic Resource
    Electronic Resource
    Increased hepatic secretion of very-low-density lipoprotein apolipoprotein B-100 in NIDDM (1995)
    Springer
    Diabetologia 38 (1995), S. 959-967 
    Details
    ISSN: 1432-0428
    Keywords: Key words Very-low-density lipoprotein apolipoprotein B-100 ; non-insulin-dependent diabetes mellitus ; stable isotopes ; gas-chromatography mass-spectrometry ; mevalonic acid.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We measured the hepatic secretion of very-low-density lipoprotein apolipoprotein B-100 (VLDL apoB) using a stable isotope gas-chromatography mass-spectrometry method in six patients with non-insulin-dependent diabetes mellitus (NIDDM) (four males, two females, age 57.5 ± 2.2 years (mean ± SEM), weight 88.2 ± 5.5 kg, glycated haemoglobin (HbA1) 8.5 ± 0.5 %, plasma total cholesterol concentration 5.7 ± 0.5 mmol/l, triglyceride 3.8 ± 0.9 mmol/l, high-density lipoprotein (HDL) cholesterol 1.0 ± 0.1 mmol/l) and six non-diabetic subjects matched for age, sex and weight (four males, two females, age 55.7 ± 2.8 years, weight 85.8 ± 5.6 kg, HbA1 6.5 ± 0.1 %, plasma total cholesterol concentration 5.7 ± 0.5 mmol/l, triglyceride 1.2 ± 0.1 mmol/l, HDL cholesterol 1.4 ± 0.1 mmol/l). HbA1, plasma triglyceride and mevalonic acid (an index of cholesterol synthesis in vivo) concentrations were significantly higher in the diabetic patients than in the non-diabetic subjects (p = 0.006, p = 0.02 and p = 0.004, respectively). VLDL apoB absolute secretion rate was significantly higher in the diabetic patients compared with the non-diabetic subjects (2297 ± 491 vs 921 ± 115 mg/day, p 〈 0.05), but there was no significant difference in the fractional catabolic rate of VLDL apoB. There was a positive correlation between VLDL apoB secretion rate and (i) fasting C-peptide (r = 0.84, p = 0.04) and (ii) mevalonic acid concentration (r = 0.83, p 〈 0.05) in the diabetic patients but not in the non-diabetic subjects. There was also a significant positive association between plasma mevalonic acid and plasma C-peptide (r = 0.82, p 〈 0.05) concentrations in the diabetic patients. We conclude that in NIDDM, there is increased hepatic secretion of VLDL apoB which may partly explain the dyslipoproteinaemia seen in this condition. We suggest that increased secretion of this apolipoprotein may be a consequence of resistance to the inhibitory effect of insulin on VLDL apoB secretion. Insulin resistance may also be the mechanism by which cholesterol synthesis, a regulator of apoB secretion, is increased in NIDDM. [Diabetologia (1995) 38: 959–967]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400586
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  • 5
    Electronic Resource
    Electronic Resource
    Increased hepatic secretion of very-low-density lipoprotein apolipoprotein B-100 in NIDDM (1995)
    Springer
    Diabetologia 38 (1995), S. 959-967 
    Details
    ISSN: 1432-0428
    Keywords: Very-low-density lipoprotein apolipoprotein B-100 ; non-insulin-dependent diabetes mellitus ; stable isotopes ; gas-chromatography mass-spectrometry ; mevalonic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We measured the hepatic secretion of very-low-density lipoprotein apolipoprotein B-100 (VLDL apoB) using a stable isotope gas-chromatography mass-spectrometry method in six patients with non-insulin-dependent diabetes mellitus (NIDDM) (four males, two females, age 57.5±2.2 years (mean±SEM), weight 88.2±5.5 kg, glycated haemoglobin (HbA1) 8.5±0.5%, plasma total cholesterol concentration 5.7±0.5 mmol/l, triglyceride 3.8±0.9 mmol/l, high-density lipoprotein (HDL) cholesterol 1.0±0.1 mmol/l) and six non-diabetic subjects matched for age, sex and weight (four males, two females, age 55.7±2.8 years, weight 85.8±5.6 kg, HbA1 6.5±0.1%, plasma total cholesterol concentration 5.7±0.5 mmol/l, triglyceride 1.2±0.1 mmol/l, HDL cholesterol 1.4±0.1 mmol/l). HbA1, plasma triglyceride and mevalpnic acid (an index of cholesterol synthesis in vivo) concentrations were significantly higher in the diabetic patients than in the non-diabetic subjects (p=0.006, p=0.02 and p=0.004, respectively). VLDL apoB absolute secretion rate was significantly higher in the diabetic patients compared with the non-diabetic subjects (2297±491 vs 921±115 mg/day, p〈0.05), but there was no significant difference in the fractional catabolic rate of VLDL apoB. There was a positive correlation between VLDL apoB secretion rate and (i) fasting C-peptide (r=0.84, p=0.04) and (ii) mevalonic acid concentration (r=0.83, p〈0.05) in the diabetic patients but not in the non-diabetic subjects. There was also a significant positive association between plasma mevalonic acid and plasma C-peptide (r=0.82, p〈0.05) concentrations in the diabetic patients. We conclude that in NIDDM, there is increased hepatic secretion of VLDL apoB which may partly explain the dyslipoproteinaemia seen in this condition. We suggest that increased secretion of this apolipoprotein may be a consequence of resistance to the inhibitory effect of insulin on VLDL apoB secretion. Insulin resistance may also be the mechanism by which cholesterol synthesis, a regulator of apoB secretion, is increased in NIDDM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400586
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  • 6
    Electronic Resource
    Electronic Resource
    Probing termite social systems through allozyme and mtDNA analysis: a case study of Nasutitermes nigriceps and Nasutitermes costalis (Isoptera, Termitidae) (1998)
    Springer
    Insectes sociaux 45 (1998), S. 289-299 
    Details
    ISSN: 1420-9098
    Keywords: Key words: Reproduction, termites, population genetics, allozyme, mtDNA.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: Certain termite genera exhibit a high degree of variation with respect to the number and developmental origin of reproductives within single colonies. Although such variation is expected to influence patterns of intracolonial competition and cooperation, it has thus far been difficult to investigate. This study exploits both allozyme and mtDNA analysis of colony offspring to infer the reproductive composition of single colonies. This study focuses on two species of Nasutitermes which differ in their social structure - colonies of N. nigriceps are generally led by a single mated pair, while those of N. costalis are regularly polygamous. MtDNA analysis on N. nigriceps shows that all colony members share the same haplotype, even in those cases where allozyme genotype frequencies suggest that colony offspring are derived from more than one reproductive pair. Similar work on N. costalis revealed a complete lack of mtDNA and allozyme variation. It is discussed how breeding system shifts from monogamy to polygamy in termites may be facilitated by population bottlenecks which reduce genetic diversity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000400050089
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  • 7
    Electronic Resource
    Electronic Resource
    A topoisomerase II cleavage site is associated with a novel mitochondrial DNA deletion (1995)
    Springer
    Human genetics 〈Berlin〉 95 (1995), S. 75-81 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mitochondrial myopathies and encephalopathies can be caused by nucleotide substitutions, deletions or duplications of the mitochondrial DNA (mtDNA). In one such disorder, Kearns-Sayre Syndrome (KSS), large-scale hetero-plasmic mtDNA deletions are often found. We describe a 14-year-old boy with clinical features of KSS, plus some additional features. Analysis of the entire mitochondrial genome by the polymerase chain reaction and Southern blotting revealed a 7864-bp mtDNA deletion, heteroplasmic in its tissue distribution. DNA sequencing established that the deletion was between nucleotides 6238 and 14103, and flanked by a 4-bp (TCCT) direct repeat sequence. Deletions between direct repeats have been hypothesised to occur by a slipped-mismatching or illegitimate recombination event, or following the DNA cleavage action of topoisomerase II. Analysis of the gene sequence in the region surrounding the mtDNA deletion breakpoint in this patient revealed the presence of putative vertebrate topoisomerase II sites. We suggest that direct repeat sequences, together with putative topoisomerase II sites, may predispose certain regions of the mitochondrial genome to deletions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225079
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  • 8
    Electronic Resource
    Electronic Resource
    Thermogravimetric–differential thermal analysis of the solid-state decomposition of ammonium tetrathiomolybdate during heating in argon (1998)
    Springer
    Journal of materials science 33 (1998), S. 3079-3083 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The formation of MoS2 by thermal decomposition of ammonium tetrathiomolybdate (ATT) solids under an argon atmosphere has been studied by simultaneous thermogravimetric and differential thermal analysis. The sequential products for the decomposition upon heating to 700 °C is ATT (hydrated)→(NH4)2MoS4→(NH4)HMoS4→H2MoS4→MoS3→ Mo2S5→MoS2. MoS2 forms between 230 and 260 °C and remains stable up to about 360 °C when it tends to be oxidized by residual oxygen, if present in the atmosphere. These findings suggest that the synthesis of MoS2 from (NH4)2MoS4 via formation of MoS3 is not a direct process, as previously reported, but rather a complex process involving a number of intermediate products (NH4)HMoS4, H2MoS4 and Mo2S5 which have not been reported before. That these products are only specific to the very narrow temperature regimes as revealed suggests that they are very unstable and short lived, that their presence is transient in nature and thus that ex-situ characterization of them is normally difficult. The presence of these intermediate products, as justified experimentally, is further interpreted in terms of their mutual structural similarities which improve understanding as to why MoS2 can usually be prepared from ATT by thermal decomposition, as in this case, or by other techniques, such as anodizing. Laminar morphology of MoS2 is revealed by transmission electron microscopy and its crystal structure examined by selected-area diffraction. Further ex-situ examination by X-ray photoelectron spectroscopy of this end product supports the feasibility of preparing MoS2 from aqueous solutions by anodizing. © 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004335604327
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  • 9
    Electronic Resource
    Electronic Resource
    Ethics and the Ivory Tower: The Case of Academic Departments of Finance (1998)
    Springer
    Teaching business ethics 2 (1998), S. 17-34 
    Details
    ISSN: 1573-1944
    Keywords: ethics ; finance ; shareholder wealth ; business education
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy , Economics
    Notes: Abstract This study reports the results from a survey of 1,000 finance faculty members within schools of business across the U.S. concerning their knowledge of ethical transgressions as well as their attitudes towards ethics training in the curriculum. Ethical breaches appear most frequently with the unauthorized duplication of licensed software and the misuse of university resources for private consulting activity. Yet knowledge of ethical misconduct is highly segmented, with significant differences in reporting frequency between groups based upon citizenship, academic rank and school size. Contrary to the implications of Hawley (1991), we find there is a widely held belief by finance educators that business ethics has a legitimate role in business curriculums and should be included in finance course work. Further, our respondents strongly reject the notions that ethical practices are inconsistent with the principle of shareholder wealth maximization or that finance is more susceptible to ethical transgressions than other functional areas of business. We conclude that finance faculty are able to serve as legitimate ethical mentors for students and by implication may positively influence future corporate ethical behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009745812749
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of molybdenum disulphide by acidification of ammonium tetrathiomolybdate solutions (1996)
    Springer
    Journal of materials science 15 (1996), S. 494-496 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00275411
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