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  • 1
    Electronic Resource
    Electronic Resource
    Colony structure of a bamboo-dwellingTetraponera sp. (Hymenoptera: Formicidae: Pseudomyrmecinae) from Malaysia (1994)
    Springer
    Insectes sociaux 41 (1994), S. 29-41 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01240571
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  • 2
    Electronic Resource
    Electronic Resource
    A comparative study on antibodies to nucleoli and 5-hydroxytryptamine in patients with fibromyalgia syndrome and tryptophan-induced eosinophilia-myalgia syndrome (1994)
    Springer
    Journal of molecular medicine 72 (1994), S. 541-549 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00207485
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics and sedimentation velocity in charge-stabilized colloidal suspensions (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 963-979 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF02458782
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  • 4
    Electronic Resource
    Electronic Resource
    Understanding colloidal charge renormalization from surface chemistry: Experiment and theory (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9924-9936 
    Details
    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
    URL: http://dx.doi.org/10.1063/1.467894
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of titanium and absorbable polymeric surgical clips for use in laparoscopic cholecystectomy (1994)
    Springer
    Surgical endoscopy and other interventional techniques 8 (1994), S. 753-758 
    Details
    ISSN: 1432-2218
    Keywords: Absorbable clips ; Metallic clips ; Laparoscopic cholecystectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The use of hemostatic surgical clips is crucial in laparoscopic surgery. Metal clips can cause significant interference with computerized tomography, may have poor holding power, and may erode into important anatomic structures. Polymeric absorbable clips, which have advantages over metallic clips, are evaluated in this study. In vitro and in vivo studies were undertaken to evaluate the hold force, rate of degradation, tissue reactivity and safety of absorbable polymeric clips. Absorbable and titanium clips were applied across excised canine cystic ducts and both axial and transverse pull-off forces were measured. In the second phase, absorbable clips were implanted subcutaneously into male rats and the strength remaining within the clips was measured after 7, 10, 14, or 21 days. In phase 3, 30 pigs were randomized into six groups and each animal underwent a laparoscopic cholecystectomy. The cystic duct and artery were ligated with absorbable polymeric clips (experimental group) or titanium clips (control group). Animals were sacrificed at 7, 14, or 28 days and a celiotomy was performed. Intraabdominal adhesions were assessed and scored. The force required to dislodge the absorbable clip was significantly greater than for metallic clips for both axial and transverse forces. Absorbable clip strength retention decreased over time as expected with a retention of 11% original strength by the 21st day. Adhesions were highest when bile spillage occurred, but did not differ significantly between either clip type. Absorbable polymeric clips were hemostatically effective in this laparoscopic model and may offer advantages over metallic clips.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593434
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  • 6
    Electronic Resource
    Electronic Resource
    Precision measurement of two iodine lines at 585 nm and 549 nm (1994)
    Springer
    The European physical journal 348 (1994), S. 147-150 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01289603
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  • 7
    Electronic Resource
    Electronic Resource
    A test of special relativity with stored lithium ions (1994)
    Springer
    Applied physics 59 (1994), S. 127-133 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01081163
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  • 8
    Electronic Resource
    Electronic Resource
    Fatigue crack propagation behavior of ultra high molecular weight polyethylene under mixed mode conditions (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 181-187 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Analytical studies of the stresses on and within ultra high molecular weight polyethylene joint components suggest that damage modes associated with polyethylene fatigue failure are caused by a combination of surface and subsurface crack propagation. Fatigue crack propagation tests under mixed mode loading conditions were conducted on center-cracked tension specimens machined from extruded blocks of sterilized polyethylene in an attempt to determine how fatigue cracks change direction in this material. Cyclic testing was performed using a sinusoidal wave form at a frequency of 5 Hz and an R-ratio (minimum load/ maximum load) of 0.15. Specimens had the notch oriented perpendicular to the direction of applied load and at angles of 60° and 45° to the loading direction. Numerical analyses were used to interpret the experimental test and to predict the fatigue behavior of polyethylene under mixed mode conditions. It was found that all cracks eventually propagated horizontally, regardless of the initial angle of inclination of the notch to the direction of applied cyclic load. In fact, the extent of the curvilinear crack growth was quite limited. An effective range of cyclic stress intensity factor was calculated for correlation with the rate of crack growth. The results followed a Paris relation, with crack growth rate linearly related to a power of the range of stress intensity, for all three crack orientations. The numerical analyses adequately modeled the experimental fatigue crack growth results. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280207
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