1,658 research outputs found
A simulation code to assist designing space missions of the Airwatch type
The design of an Airwatch type space mission can greatly benefit from a flexible simulation code for establishing the values of the main parameters of the experiment. We present here a code written for this purpose. The cosmic ray primary spectrum at very high energies, the atmosphere modelling, the fluorescence yield, the photon propagation and the detector response are taken into account in order to optimize the fundamental design parameters of the experiment, namely orbit height, field of view, mirror radius, number of pixels of the focal plane, threshold of photo-detection. The optimization criterion will be to maximize counting rates versus mission cost, which imposes limits both on weight and power consumption. Preliminary results on signals with changing energy and zenith angle of incident particles are shown
Anomalous prompt photon production in hadronic collisions at low-
We investigate the discrepancy that exists at low- between
the next--to--leading order QCD calculations of prompt photon production and
the measured cross section. The central values of the measured cross section
are of order 100\% larger than QCD predictions in this region. It has been
suggested that the bremsstrahlung contribution may account for this
discrepancy. The quark fragmentation function has not been
measured and an exactly known asymptotic form is normally used in calculations.
We examine the effect of much larger fragmentation functions on the QCD
predictions. After illustrating the effect of the large fragmentation functions
in some detail for recent CDF data at =1.8~TeV, we perform a
fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV.
While a large fragmentation function normalization may prove to play an
important role in resolving the discrepancy, the present theoretical and
experimental uncertainties prevent any definite normalization value from being
determined.Comment: 14 pages, LBL-33122 and UCB-PTH-92/38. 13 figures available by email,
specify postscript or topdrawe
Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission
The longitudinal development and other characteristics of the EECR induced
atmospheric showers can be studied from space by detecting the fluorescence
light induced in the atmospheric nitrogen. According to the Airwatch concept a
single fast detector can be used for measuring both intensity and time
development of the streak of fluorescence light produced by the atmospheric
shower induced by an EECR. In the present communication the detection
capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9
A Next-to-Leading-Order Study of Dihadron Production
The production of pairs of hadrons in hadronic collisions is studied using a
next-to-leading-order Monte Carlo program based on the phase space slicing
technique. Up-to-date fragmentation functions based on fits to LEP data are
employed, together with several versions of current parton distribution
functions. Good agreement is found with data for the dihadron mass
distribution. A comparison is also made with data for the dihadron angular
distribution. The scale dependence of the predictions and the dependence on the
choices made for the fragmentation and parton distribution functions are also
presented. The good agreement between theory and experiment is contrasted to
the case for single production where significant deviations between
theory and experiment have been observed.Comment: 22 pages, 15 figures; 3 references added, one figure modified for
clarit
Estimating the inelasticity with the information theory approach
Using the information theory approach, in both its extensive and nonextensive
versions, we estimate the inelasticity parameter of hadronic reactions
together with its distribution and energy dependence from and
data. We find that the inelasticity remains essentially constant in energy
except for a variation around , as was originally expected.Comment: 14 pages, 8 figures. Misprints correcte
A clinically aligned experimental approach for quantitative characterization of patient-specific cardiovascular models
Recent improvements in computational tools opened the possibility of patient-specific modeling to aid clinicians during diagnosis, treatment, and monitoring. One example is the modeling of blood flow for surgical planning, where modeling can help predict the prognosis. Computational analysis is used to extract hemodynamic information about the case; however, these methods are sensitive to assumptions on blood properties, boundary conditions, and appropriate geometry accuracy. When available, experimental measurements can be used to validate the results and, among the modalities, ultrasound-based methods are suitable due to their relative low cost and non-invasiveness. This work proposes a procedure to create accurate patient-specific silicone replicas of blood vessels and a power Doppler compatible experimental setup able to simulate and measure realistic flow conditions. The assessment of silicone model geometry shows small discrepancies between these and the target geometries (median of surface error lies within 57 µm and 82 μm). Power Doppler measurements were compared against computational fluid dynamics results, showing discrepancies within 10% near the wall. The experimental approach offers a setup to quantify flow in in vitro systems and provide more accurate results where other techniques (e.g., particle image velocimetry and particle tracking velocimetry) have shown limitations due to the interference of the interface
AKT1 and MYC induce distinctive metabolic fingerprints in human prostate cancer
Cancer cells may overcome growth factor dependence by deregulating oncogenic and/or tumor-suppressor pathways that affect their metabolism, or by activating metabolic pathways de novo with targeted mutations in critical metabolic enzymes. It is unknown whether human prostate tumors develop a similar metabolic response to different oncogenic drivers or a particular oncogenic event results in its own metabolic reprogramming. Akt and Myc are arguably the most prevalent driving oncogenes in prostate cancer. Mass spectrometry-based metabolite profiling was performed on immortalized human prostate epithelial cells transformed by AKT1 or MYC, transgenic mice driven by the same oncogenes under the control of a prostate-specific promoter, and human prostate specimens characterized for the expression and activation of these oncoproteins. Integrative analysis of these metabolomic datasets revealed that AKT1 activation was associated with accumulation of aerobic glycolysis metabolites, whereas MYC overexpression was associated with dysregulated lipid metabolism. Selected metabolites that differentially accumulated in the MYC-high versus AKT1-high tumors, or in normal versus tumor prostate tissue by untargeted metabolomics, were validated using absolute quantitation assays. Importantly, the AKT1/MYC status was independent of Gleason grade and pathologic staging. Our fi ndings show how prostate tumors undergo a metabolic reprogramming that refl ects their molecular phenotypes, with implications for the development of metabolic diagnostics and targeted therapeutics.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias Médica
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