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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9924-9936 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we report on the charging behavior of latex particles in aqueous suspensions. We use static light scattering and acid–base titrations as complementary techniques to observe both effective and bare particle charges. Acid–base titrations at various ionic strengths provide the pH dependent charging curves. The surface chemical parameters (dissociation constant of the acidic carboxylic groups, total density of ionizable sites and Stern capacitance) are determined from fits of a Stern layer model to the titration data. We find strong evidence that the dissociation of protons is the only specific adsorption process. Effective particle charges are determined by fits of integral equation calculations of the polydisperse static structure factor to the static light scattering data. A generalization of the Poisson–Boltzmann cell model including the dissociation of the acidic surface groups and the autodissociation of water is used to predict effective particle charges from the surface chemical parameters determined by the titration experiments. We find that the light scattering data are best described by a model where a small fraction of the ionizable surface sites are sulfate groups which are completely dissociated at moderate pH. These effective charges are comparable to the predictions by a basic cell model where charge regulation is absent. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 348 (1994), S. 147-150 
    ISSN: 1434-601X
    Keywords: 06.20.Hq ; 42.50.Wm ; 29.20.Dh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transition frequencies of thei-component of the R(99)15-1 and thew-component of the R(85)26-0 transition in the B-X system of molecular127I2 have been determined with an overall relative standard uncertainty of 1.3 · 10−10. For this purpose a commercial linear dye laser has been modified and stabilized to the corresponding iodine line. This dye laser serves as a transportable frequency standard which is compared with the wavelength standards of the PTB. The evaluation of an experiment for testing special relativity at the test storage ring (TSR) in Heidelberg is based on the precision of the reported interferometric wavelength comparison.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1440
    Keywords: Eosinophilia myalgia syndrome ; Fibromyalgia syndrome ; Anti-serotonin antibodies ; Anti-ganglioside antibodies ; Anti-phospholipid antibodies ; Anti-nucleolar antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eosinophilia myalgia syndrome (EMS) has been related to intake of “contaminated” L-tryptophan, and an alteration in tryptophan 5-hydroxytryptamine (5-HT, serotonin) metabolism has been reported in EMS patients. Recently we found that a defined autoantibody pattern consisting of antibodies to nucleoli, gangliosides, and phospholipids is closely related to the fibromyalgia syndrome (FS) which clinically resembles the EMS. We were therefore interested to see whether these antibodies can also be detected in patients with EMS. Studied were 27 patients with acute EMS (13 of whom were also examined 2 years after acute onset), 100 patients with FS, and 40 patients with progressive systemic sclerosis (PSS). As controls, sera from 100 blood donors were analyzed. Antibodies to nucleoli were demonstrated by immunofluorescence test on cell cultures in 52% of patients with acute EMS, 62% of patients with chronic EMS, and 37% of FS patients. Western blotting with a nuclear extract from HeLa cells revealed in both diseases the same epitopes at 63, 57, and 53 kDa. Antibodies to 5-HT, gangliosides (Gm1), and phospholipids were determined by enzyme-linked immunosorbent assay. Among patients with FS 73% had antibodies to 5-HT, in contrast to only 19% of patients with acute EMS. However, 77% of the 13 EMS patients analyzed 2 years later had become anti-5-HT antibody positive during that time. Also the incidence of antibodies to Gm1 increased from 37% at acute onset to 69% in patients with chronic EMS (30%). The various antibodies were detected in only 18% of healthy controls. Serum 5-HT levels were decreased in patients with acute EMS compared to those with chronic EMS or FS. In patients with PSS they were significantly increased. It is concluded that EMS may have been developed in patients with FS who may have reacted in an allergic manner to a more immunogenic (“contaminated”) L-tryptophan.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric radiology 23 (1993), S. 355-356 
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 3-year-old boy with a radiographic finding of an isolated invaginated Meckel's diverticulum is presented. The abnormality simulates a polypoid filling defect in the distal small bowel on barium examination. This particular manifestation of Meckel's diverticulum is very rare and has been reported only once previously. This article re-emphasizes the need to think about this possibility when a polypoid filling defect is seen in the distal small bowel. At the time laparotomy was performed, the abnormality had progressed into a triple intussusception, a rare surgical finding.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0649
    Keywords: 03.30.+p ; 29.20Dh ; 42.50.Wm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Laser spectroscopy at the heavy ion storage ring TSR in Heidelberg allows for precision experiments testing the limits of the special theory of relativity. With an opticalΛ-type three-level system of7Li+ the Doppler shift has been measured by saturation spectroscopy as a test of the time dilatation factor γ = (1 −β 2)−1/2 at an ion velocity ofυ = 6.4% c. A precision ofΔν/ν 〈 9 × 10−9 has been obtained, which sets a second-order limit of 1.1 × 10−6 for any deviation from the time dilatation factor. The fourth-order limit of this deviation is set below 2.7 × 10−4 by the present experiment. These limits are given at a 1 σ confidence level.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 963-979 
    ISSN: 0392-6737
    Keywords: Colloids ; Statistical theories of liquid structure ; Time-dependent properties ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Charge-stabilized suspensions are characterized by the strong electrostatic interactions between the particles so that rather dilute systems may exhibit strong correlation resulting in a well-developed short-range order. This microstructure, quantitatively described by the pair distribution functiong(r), is rather different from that of (uncharged) hard spheres. It is shown how this difference affects the «hydrodynamic function»H(k), which appears in the expression for the first cumulant Γ(k)=k 2 D eff(k)=k 2 H(k)/S(k) of the dynamic autocorrelation function. Without hydrodynamic interaction,H(k)=D 0, which is the free-diffusion coefficient. Using pairwise additive hydrodynamic interaction and the lowest-order many-body theory of hydrodynamic interaction, it is found thatH(k) can deviate considerably fromD 0 even for systems of volume fractions ϕ as low as 10−3. These effects are more pronounced for collective diffusion than for self-diffusion. SinceH(k=0) is closely related to the sedimentation velocity, we have studied this quantity as a function of volume fraction. It is found that (H(0)/D 0) −1 scales asφ 1/3 at low ϕ in salt-free suspensions.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Endothelial cells ; very low density lipoprotein subfractions ; diabetes mellitus ; atherosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The very low density lipoprotein (VLDL) fraction was isolated from 11 normolipidaemic Type 1 (insulin-dependent) diabetic patients in good to fair glycaemic control and from 11 age-, sex- and race-matched, non-diabetic, control subjects. The rate of receptor-mediated degradation by human endothelial cells was significantly greater (p〈0.02) for the total VLDL fraction isolated from diabetic patients compared to control subjects and averaged 1008±300 and 717±150 ng·mg cell protein−1·16 h−1, respectively. The total VLDL fraction was separated into three subfractions: VLDL-I, Sf 100–400 (Sf = Svedberg units); VLDL-II, Sf 60–100; VLDL-III, Sf20–60. Rates of receptor-mediated degradation of VLDL-I and VLDL-II isolated from diabetic patients were significantly greater than the comparable subfraction isolated from control subjects and averaged 1023±279 vs 361±122 (p〈0.01) and 433±70 vs 294±70 ng·mg cell protein−1·16 h−1 (p〈0.03), respectively. Rates of receptor-mediated degradation of the V-III subfraction isolated from the two groups did not differ significantly. There were no significant differences in the chemical composition or in the plasma concentrations of the VLDL subfractions isolated from diabetic patients compared to control subjects. There was a significant increase in the apoprotein E content of VLDL-I (p〈0.01) and VLDL-II (p〈0.05) isolated from diabetic patients. There was a significant increase in the ratio of apoprotein C compared to apoprotein E (p〈0.03) in VLDL-I isolated from control subjects compared to the diabetic patients. There were no significant differences in the apoprotein composition of VLDL-III isolated from the two groups.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0428
    Keywords: Glycated haemoglobin A1 ; plasma glucose ; diabetic retinopathy ; risk factor ; receiver operating characteristic (ROC) analysis ; Pima Indians
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Among Pima Indians with Type 2 (non-insulin-dependent) diabetes mellitus the relationships between glycated haemoglobin (HbA1), fasting or 2-h post-load plasma glucose and diabetic retinopathy were examined by cross-sectional and prospective analyses, and the strengths of the associations were directly compared by receiver operating characteristic analysis. In the cross-sectional analysis, HbA1, fasting and 2-h plasma glucose were each significantly related to retinopathy among 789 diabetic subjects by separate logistic models. In a stepwise multiple logistic model in which HbA1, fasting and 2-h plasma glucose were included, HbA1 was selected as having the strongest association with retinopathy and neither fasting nor 2-h plasma glucose contributed significantly to the model once HbA1 was entered. Similarly, in the prospective analysis, HbA1, fasting and 2-h plasma glucose all predicted retinopathy in 227 diabetic subjects by separate proportional-hazards models. In a stepwise proportional-hazards model with HbA1, fasting and 2-h plasma glucose available to the model, HbA1 was again selected as having the strongest association with the incidence of retinopathy, and neither fasting nor 2-h plasma glucose significantly added to the prediction of retinopathy. A receiver operating characteristic analysis was used to determine if HbA1 was statistically significantly better than fasting or 2-h plasma glucose in assessing the risk for retinopathy. In neither the cross-sectional nor the prospective data did the area under the receiver operating characteristic curve for HbA1 differ significantly from that for fasting or 2-h plasma glucose (p〉0.05 for each). In conclusion, HbA1, an integrated measure of blood glucose concentration over a period of 2–3 months, is slightly more closely associated with the prevalence and incidence of diabetic retinopathy than a single blood glucose determination. However, the differences between HbA1 and fasting or 2-h plasma glucose in assessing the association with or the risk for retinopathy are not significant.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1420-9098
    Keywords: Tetraponera ; bamboo ; ants ; nest flooding ; water removal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Southeast Asian antTetraponera sp. nearattenuata F. Smith inhabits internodes of large bamboo species that it shares with symbiotic pseudococcids. It finds access to this nesting habitat via small holes made by wood-boring insects. During heavy rain, runoff water collects in these punctured internodes. TheTetraponera workers remove the water by ingesting it, walking to the entrance hole, and regurgitating it to the outside. In this way, they 1) reduce the danger of colony members drowing, 2) enable their symbionts to feed also on the internode floor, and 3) prevent excessive growth of microbes in the nest.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1420-9098
    Keywords: Tetraponera ; bamboo ; ants ; colony structure ; polydomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The colony structure of the bamboo-inhabiting SE-Asian pseudomyrmecine antTetraponera sp. PSW-80 nearattenuata F. Smith was investigated at the Ulu Gombak Field Studies Centre, Selangor, West-Malaysia. Based on the dissection of 54 stem internodes from 12 different culms of the large bambooGigantochloa scortechinii Gamble and on the mapping of three colonies, the following demographic characteristics emerge. The colonies are monogynous but highly polydomous (at least up to 36 internodes and up to 9 stems occupied) and very populous for a pseudomyrmecine not involved in an ant-plant mutualism. One completely censused colony had 6953 adult workers and 2079 alates (adults plus pupae). The single queen suppresses gyne development in her own “nest” and, to a lesser extent, in other “nests” within the same stem. The overall numerical sex ratio was 0.96∶1 (females:males), the investment sex ratio, 2.93∶1, i.e., almost exactly the 3∶1 ratio expected for a monogynous outbred hymenopteran in which the colony queen also produces all the male offspring. Brood is distributed to all other nest chambers from the queenright chamber. The symbiotic pseudococcids (Kermicus wroughtoni Newstead) are present in all inhabited internodes, with small early instar individuals prevailing numerically by far over the larger stages. The rieht well secluded honeydew supply within the internode and the efficient architectural protection provided by the internode wall (access usually only through a 2 × 3 mm-hole) allowT. sp. PSW-80 to reach an unusually large colony size without being an aggressive and protective plant mutualist like other members of its subfamily with similar demographic features.
    Type of Medium: Electronic Resource
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