736 research outputs found
A tow concept for the space shuttle orbiter approach and landing test
The tow concept provides the means for evaluating the orbiter aerodynamic performance and handling qualities in the same configuration as expected in actual space shuttle flight operation. A Boeing 747-100 aircraft has engine-out capability to tow the orbiter to an altitude that permits a safe orbiter approach and landing. The tow concept also provides a means for conducting a comprehensive ground test program before proceeding into the actual ALT flight operations. The implementation of the tow concept requires only a minor structural modification in the nose section of the orbiter vehicle; requires minor modifications in the 747 cargo bay; and makes use of those orbiter onboard systems installed in the ALT orbiter vehicle. The 747 wake turbulence does not constitute a problem for the orbiter during take-off or climb to altitude. The impact that the tow concept would have on the cost and schedule of the space shuttle program was not evaluated in this study
Aircraft energy efficiency laminar flow control wing design study
An engineering design study was performed in which laminar flow control (LFC) was integrated into the wing of a commercial passenger transport aircraft. A baseline aircraft configuration was selected and the wing geometry was defined. The LFC system, with suction slots, ducting, and suction pumps was integrated with the wing structure. The use of standard aluminum technology and advanced superplastic formed diffusion bonded titanium technology was evaluated. The results of the design study show that the LFC system can be integrated with the wing structure to provide a structurally and aerodynamically efficient wing for a commercial transport aircraft
Molecular targeted therapies in head and neck cancer - An update of recent developements -
Targeted therapies have made their way into clinical practice during the past decade. They have caused a major impact on the survival of cancer patients in many areas of clinical oncology and hematology. Indeed, in some hematologic malignancies, such as chronic myelogenous leukemia or non-Hodgkin's lymphomas, biologicals and antibodies specifically designed to target tumour-specific proteins have revolutionized treatment standards. In solid tumours, new drugs targeting EGF- or VEGF- receptors are now approved and are entering clinical practise for treatment of colon, lung, kidney and other cancers, either alone or in combination with conventional treatment approaches
Sequence-dependent effects of ZD1839 (‘Iressa’) in combination with cytotoxic treatment in human head and neck cancer
Elevated levels of epidermal growth factor receptor in head and neck cancer have been extensively reported, and are correlated with poor prognosis. The combination of cisplatin and 5-fluorouracil is a standard treatment regimen for head and neck cancer, with radiation representing another therapeutic option. Six head and neck cancer cell lines were used to study the cytotoxic effects of combining ZD1839 (‘Iressa’), a new selective epidermal growth factor receptor tyrosine kinase inhibitor, and radiation. Two of the cell lines were also used to study the combination of ZD1839 and cisplatin/5-fluorouracil. Cytotoxic effects were assessed by the MTT test. The results indicated that ZD1839 applied before radiation gave the best effects (P=0.002); an effect that was strongest in those p53-mutated cell lines that express the highest epidermal growth factor receptor levels. The effects of ZD1839 with cisplatin and/or 5-fluorouracil were sequence dependent (P<0.003), with the best results achieved when ZD1839 was applied first. For the triple combinations, ZD1839 applied before cisplatin and 5-fluorouracil resulted in a slight synergistic effect (P=0.03), although the effect was greater when ZD1839 was applied both before and during cytotoxic drug exposure. In conclusion, ZD1839 applied before radiation and before and/or during cisplatin/5-fluorouracil may improve the efficacy of treatment for head and neck cancer
Hidden chromosomal abnormalities in pleuropulmonary blastomas identified by multiplex FISH
BACKGROUND: Pleuropulmonary blastoma (PPB) is a rare childhood dysontogenetic intrathoracic neoplasm associated with an unfavourable clinical behaviour. CASES PRESENTATION: We report pathological and cytogenetic findings in two cases of PPB at initial diagnosis and recurrence. Both tumors were classified as type III pneumoblastoma and histological findings were similar at diagnosis and relapse. In both cases, conventional cytogenetic techniques revealed complex numerical and structural chromosomal abnormalities. Molecular cytogenetic analysis (interphase/metaphase FISH and multicolor FISH) identified accurately chromosomal aberrations. In one case, TP53 gene deletion was detected on metaphase FISH. To date, only few cytogenetic data have been published about PPB. CONCLUSION: The PPB genetic profile remains to be established and compared to others embryonal neoplasia. Our cytogenetic data are discussed reviewing cytogenetics PPBs published cases, illustrating the contribution of multicolor FISH in order to identify pathogenetically important recurrent aberrations in PPB
System-Size Independence of Directed Flow Measured at the BNL Relativistic Heavy-Ion Collider
We measure directed flow (ν_1) for charged particles in Au+Au and Cu+Cu collisions at √S_(NN)=200 and 62.4 GeV, as a function of pseudorapidity (η), transverse momentum (p_t), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to ν_1 in different collision systems, and investigate possible explanations for the observed sign change in ν_1(p_t)
Measurements of meson production in relativistic heavy-ion collisions at RHIC
We present results for the measurement of meson production via its
charged kaon decay channel in Au+Au collisions at
, 130, and 200 GeV, and in and +Au collisions
at GeV from the STAR experiment at the BNL Relativistic
Heavy Ion Collider (RHIC). The midrapidity () meson transverse
momentum () spectra in central Au+Au collisions are found to be well
described by a single exponential distribution. On the other hand, the
spectra from , +Au and peripheral Au+Au collisions show power-law tails
at intermediate and high and are described better by Levy
distributions. The constant yield ratio vs beam species, collision
centrality and colliding energy is in contradiction with expectations from
models having kaon coalescence as the dominant mechanism for production
at RHIC. The yield ratio as a function of is consistent
with a model based on the recombination of thermal quarks up to GeV/, but disagrees at higher transverse momenta. The measured nuclear
modification factor, , for the meson increases above unity at
intermediate , similar to that for pions and protons, while is
suppressed due to the energy loss effect in central Au+Au collisions. Number of
constituent quark scaling of both and for the meson
with respect to other hadrons in Au+Au collisions at =200 GeV
at intermediate is observed. These observations support quark
coalescence as being the dominant mechanism of hadronization in the
intermediate region at RHIC.Comment: 22 pages, 21 figures, 4 table
Pion interferometry in Au+Au collisions at = 200 GeV
We present a systematic analysis of two-pion interferometry in Au+Au
collisions at = 200 GeV using the STAR detector at RHIC. We
extract the HBT radii and study their multiplicity, transverse momentum, and
azimuthal angle dependence. The Gaussianess of the correlation function is
studied. Estimates of the geometrical and dynamical structure of the freeze-out
source are extracted by fits with blast wave parameterizations. The expansion
of the source and its relation with the initial energy density distribution is
studied.Comment: 21 pages, 30 figures. As published in Physics Review
Enhanced strange baryon production in Au+Au collisions compared to p+p at sqrts = 200 GeV
We report on the observed differences in production rates of strange and
multi-strange baryons in Au+Au collisions at sqrts = 200 GeV compared to pp
interactions at the same energy. The strange baryon yields in Au+Au collisions,
then scaled down by the number of participating nucleons, are enhanced relative
to those measured in pp reactions. The enhancement observed increases with the
strangeness content of the baryon, and increases for all strange baryons with
collision centrality. The enhancement is qualitatively similar to that observed
at lower collision energy sqrts =17.3 GeV. The previous observations are for
the bulk production, while at intermediate pT, 1 < pT< 4 GeV/c, the strange
baryons even exceed binary scaling from pp yields.Comment: 7 pages, 4 figures. Printed in PR
Hadronic resonance production in +Au collisions at = 200 GeV at RHIC
We present the first measurements of the , (892),
(1232), (1385), and (1520) resonances in +Au
collisions at = 200 GeV, reconstructed via their hadronic
decay channels using the STAR detector at RHIC. The masses and widths of these
resonances are studied as a function of transverse momentum (). We observe
that the resonance spectra follow a generalized scaling law with the transverse
mass (). The of , , and . The , ,
, , and ratios in
+Au collisions are compared to the measurements in minimum bias
interactions, where we observe that both measurements are comparable. The
nuclear modification factors () of the , , and
scale with the number of binary collisions () for 1.2 GeV/.Comment: STAR Collaboration. Submitted to PR
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