3,786 research outputs found
BIOMECHANICAL ASPECTS OF THE POLE VAULT - ANALYSlS OF THE 4th IAAF WORLD CHAMPIONSHIP
World class pole vaulters were analysed at the 4th IAAF World Championships in Stuttgart, 1993 Performance relevant parameters were obtained using standard APAS procedures. DLT for non-panning cameras provided spatial coordinates for the 3-d analysis Graphical and numerical postprocessing of the data was done using Excel. In addition to the video graphic recording, the event was filmed with two panned 16mm Locam cameras operating at 100 Hz to determine temporal parameters. Furthermore approach velocities were measured using doubled IR photocells. Vertical CM accelerations in the free flight phase verified, that the digitally filtered data are reliable despite the large object space There was little lateral motion of the CM. Thus, for many applications, a 2-d analysis can be justified. Top vaulters clear heights 1,Zm above their grip height. Huffman cleared 5,Sm using a new 'straddle like' clearance. This was 1,17m above grip height. Compared to major competitions in the last decade approach speed stagnated or even decreased while performance improved. However, better vaulters tend to have higher speed and acceleration into the last approach section. High approach speed is a necessary but non-sufficient prerequisite for high vaults. Analysis of the time course of potential and kinetic energy reveals the importance of the enery at takeoff and the work done on the pole. These factors are not independent of each other. Thus, there is an optimum relationship between energy produced in the respective phases of the vault. This optimum depends on the current technical and conditional standard of the athlete. The inter- and intraindividual variations in the measured parameters support the notion, that compensation does take place and is indeed a common strategy on the world class level. Optimum technique remains a time variant, individual and situation specific motor pattern
Purification and quantification of recombinant Epstein-Barr viral glycoproteins gp350/220 from Chinese hamster ovary cells
Truncated Epstein-Barr virus (EBV) membrane antigen gp350/220 (EBV-MA) lacking the membrane anchor was expressed and secreted into the medium of recombinant Chinese hamster ovary cells that had been cultured in Plasmapur hollow-fibre modules using defined serum-free medium. The EBV-MA in the medium was concentrated by 70% (w/v) ammonium sulphate precipitation and subsequently purified by immunoaffinity chromatography using an anti-EBV-MA (EBV.0T6) monoclonal antibody (mAb) column. Adsorbed antigen was eluted with 3 M MgCl2 in phosphate-buffered saline, concentrated by Mono Q anion-exchange chromatography and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, silver staining and Western blotting using EBV-positive serum and anti-EBV-MA specific mAbs. Monospecific polyclonal rabbit antibodies against the purified EBV-MA were raised and purified by protein G affinity chromatography. For the measurement of EBV-MA antigen levels a sandwich enzyme-linked immunosorbent assay using rabbit polyclonal antibodies and a horseradish peroxidase-conjugated anti-MA mAb was developed having a detection level of 10 ng/ml
Nearly 5000 Distant Early-Type Galaxies in COMBO-17: a Red Sequence and its Evolution since z~1
We present the rest-frame colors and luminosities of ~25000 m_R<24 galaxies
in the redshift range 0.2<z<1.1, drawn from 0.78 square degrees of the COMBO-17
survey. We find that the rest-frame color distribution of these galaxies is
bimodal at all redshifts out to z~1. This bimodality permits a
model-independent definition of red, early-type galaxies and blue, late-type
galaxies at any given redshift. The colors of the blue peak become redder
towards the present day, and the number density of blue luminous galaxies has
dropped strongly since z~1. Focusing on the red galaxies, we find that they
populate a color-magnitude relation. Such red sequences have been identified in
galaxy cluster environments, but our data show that such a sequence exists over
this redshift range even when averaging over all environments. The mean color
of the red galaxy sequence evolves with redshift in a way that is consistent
with the aging of an ancient stellar population. The rest-frame B-band
luminosity density in red galaxies evolves only mildly with redshift in a
Lambda-dominated cold dark matter universe. Accounting for the change in
stellar mass-to-light ratio implied by the redshift evolution in red galaxy
colors, the COMBO-17 data indicate an increase in stellar mass on the red
sequence by a factor of two since z~1. The largest source of uncertainty is
large-scale structure, implying that considerably larger surveys are necessary
to further refine this result. We explore mechanisms that may drive this
evolution in the red galaxy population, finding that both galaxy merging and
truncation of star formation in some fraction of the blue, star-forming
population are required to fully explain the properties of these galaxies.Comment: To appear in the Astrophysical Journal 20 June 2004. 16 pages, 6
embedded figures. Substantial revision of photometric redshifts and extensive
minor changes to the paper throughout: conclusions unchange
A 2-pyridone-amide inhibitor targets the glucose metabolism pathway of Chlamydia trachomatis.
UnlabelledIn a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection.ImportanceChlamydia trachomatis is a bacterial pathogen of humans that causes a common sexually transmitted disease as well as eye infections. It grows only inside cells of its host organism, within a parasitophorous vacuole termed the inclusion. Little is known, however, about what bacterial components and processes are important for C. trachomatis cellular infectivity. Here, by using a visual screen for compounds that affect bacterial distribution within the chlamydial inclusion, we identified the inhibitor KSK120. As hypothesized, the altered bacterial distribution induced by KSK120 correlated with a block in C. trachomatis infectivity. Our data suggest that the compound targets the glucose-6-phosphate (G-6P) metabolism pathway of C. trachomatis, supporting previous indications that G-6P metabolism is critical for C. trachomatis infectivity. Thus, KSK120 may be a useful tool to study chlamydial glucose metabolism and has the potential to be used in the treatment of C. trachomatis infections
CIK Cells and HDAC Inhibitors in Multiple Myeloma
Multiple myeloma is the second most common hematological malignancy. Despite all the progress made in treating multiple myeloma, it still remains an incurable disease. Patients are left with a median survival of 4-5 years. The combined treatment of multiple myeloma with histone deacetylase inhibitors and cytokine-induced killer cells provides a promising targeted treatment option for patients. This study investigated the impact of a combined treatment compared to treatment with histone deacetylase inhibitors. The experiments revealed that a treatment with histone deacetylase (HDAC) inhibitors could reduce cell viability to 59% for KMS 18 cell line and 46% for the U-266 cell line. The combined treatment led to a decrease of cell viability to 33% for KMS 18 and 27% for the U-266 cell line, thus showing a significantly better efficacy than the single treatment
Towards an understanding of the rapid decline of the cosmic star formation rate
We present a first analysis of deep 24 micron observations with the Spitzer
Space Telescope of a sample of nearly 1500 galaxies in a thin redshift slice,
0.65<z<0.75. We combine the infrared data with redshifts, rest-frame
luminosities, and colors from COMBO-17, and with morphologies from Hubble Space
Telescope images collected by the GEMS and GOODS projects. To characterize the
decline in star-formation rate (SFR) since z~0.7, we estimate the total thermal
infrared (IR) luminosities, SFRs, and stellar masses for the galaxies in this
sample. At z~0.7, nearly 40% of intermediate and high-mass galaxies (with
stellar masses >2x10^10 solar masses) are undergoing a period of intense star
formation above their past-averaged SFR. In contrast, less than 1% of
equally-massive galaxies in the local universe have similarly intense star
formation activity. Morphologically-undisturbed galaxies dominate the total
infrared luminosity density and SFR density: at z~0.7, more than half of the
intensely star-forming galaxies have spiral morphologies, whereas less than
\~30% are strongly interacting. Thus, a decline in major-merger rate is not the
underlying cause of the rapid decline in cosmic SFR since z~0.7. Physical
properties that do not strongly affect galaxy morphology - for example, gas
consumption and weak interactions with small satellite galaxies - appear to be
responsible.Comment: To appear in the Astrophysical Journal 1 June 2005. 14 pages with 8
embedded figure
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