663 research outputs found
The Underlying Event and the Total Cross Section from Tevatron to the LHC
Multiple partonic interactions are widely used to simulate the hadronic final
state in high energy hadronic collisions, and successfully describe many
features of the data. It is important to make maximum use of the available
physical constraints on such models, particularly given the large extrapolation
from current high energy data to LHC energies. In eikonal models, the rate of
multiparton interactions is coupled to the energy dependence of the total cross
section. Using a Monte Carlo implementation of such a model, we study the
connection between the total cross section, the jet cross section, and the
underlying event. By imposing internal consistency on the model, we derive
constraints on its parameters at the LHC. By imposing internal consistency on
the model and comparing to current data we constrain the allowed range of its
parameters. We show that measurements of the total proton-proton cross-section
at the LHC are likely to break this internal consistency, and thus to require
an extension of the model. Likely such extensions are that hard scatters probe
a denser matter distribution inside the proton in impact parameter space than
soft scatters, a conclusion also supported by Tevatron data on double-parton
scattering, and/or that the basic parameters of the model are energy dependent.Comment: 17 pages, 6 figures, version accepted by JHE
Исследование процессов структурообразования и саморазогрева в бинарной порошковой смеси Ti-Al в режиме статического теплового взрыва на основе диаграммы состояния
На основе равновесной диаграммы состояния системы Ti-Al разработана математическая модель процессов фазообразования в режиме статического теплового взрыва порошковой смеси при температурах, превышающих температуру плавления легкоплавкого компонента. Получены термограммы процесса саморазогрева, исследована динамика процессов структурообразования с использованием методов численного моделирования для стехиометрии соединений TiAl[3] и TiAl. Показано, что результаты расчетов обнаруживают удовлетворительное качественное согласование с экспериментальными данными
Selective Enzymatic Oxidation of Silanes to Silanols
Compared to the biological world's rich chemistry for functionalizing carbon, enzymatic transformations of the heavier homologue silicon are rare. We report that a wild‐type cytochrome P450 monooxygenase (P450_(BM3) from Bacillus megaterium, CYP102A1) has promiscuous activity for oxidation of hydrosilanes to give silanols. Directed evolution was applied to enhance this non‐native activity and create a highly efficient catalyst for selective silane oxidation under mild conditions with oxygen as the terminal oxidant. The evolved enzyme leaves C−H bonds present in the silane substrates untouched, and this biotransformation does not lead to disiloxane formation, a common problem in silanol syntheses. Computational studies reveal that catalysis proceeds through hydrogen atom abstraction followed by radical rebound, as observed in the native C−H hydroxylation mechanism of the P450 enzyme. This enzymatic silane oxidation extends nature's impressive catalytic repertoire
Extension of an automatic building extraction technique to airborne laser scanner data containing damaged buildings
Airborne laser scanning systems generate 3-dimensional point clouds of high density and irregular spacing. These data consist of multiple returns coming from terrain, buildings, and vegetation. The major difficulty is the extraction of object categories, usually buildings. In the field of disaster management, the detection of building damages plays an important role. Therefore, the question arises, if damaged buildings can also be detected by a method developed for the automatic extraction of buildings. Another purpose of this study is to extend and test an automatic building detection method developed initially for first echo laser scanner data on data captured in first and last echo. In order to answer these two questions, two institutes share their data and knowledge: the Institute of Photogrammetry and Remote Sensing (IPF, Universität Karlsruhe (TH), Germany) and the MAP-PAGE team (INSA de Strasbourg, France). The used 3D LIDAR data was captured over an area containing undamaged and damaged buildings. The results achieved for every single processing step by applying the original and the extended algorithm to the data are presented, analysed and compared. It is pointed out which buildings can be extracted by which algorithm and why some buildings remain undetecte
Extension of an automatic building extraction technique to airborne laser scanner data containing damaged buildings
Hunting for CDF Multi-Muon "Ghost" Events at Collider and Fixed-Target Experiments
In 2008 the CDF collaboration discovered a large excess of events containing
two or more muons, at least one of which seemed to have been produced outside
the beam pipe. We investigate whether similar "ghost" events could (and should)
have been seen in already completed experiments. The CDF di-muon data can be
reproduced by a simple model where a relatively light X particle undergoes
four-body decay. This model predicts a large number of ghost events in Fermilab
fixed-target experiments E772, E789 and E866, applying the cuts optimized for
analyses of Drell-Yan events. A correct description of events with more than
two muons requires a more complicated model, where two X particles are produced
from a very broad resonance Y. This model can be tested in fixed-target
experiments only if the cut on the angles, or rapidities, of the muons can be
relaxed. Either way, the UA1 experiment at the CERN ppbar collider should have
observed O(100) ghost events.Comment: 15 pages, 9 figure
Neuromonitoring intraoperatorio del nervo laringeo ricorrente. Un’esperienza di 1000 pazienti consecutivi
Il neuromonitoring intraoperatorio è stato introdotto in chirurgia tiroidea molti anni fa rendendo più semplice l’identificazione del nervo laringeo ricorrente e meno frequenti i danni a suo carico. Tra il
1999 e il 2005 abbiamo raccolto tutti i dati relativi ai pazienti che si sono sottoposti a chirurgia tiroidea e li abbiamo analizzati anno per anno.
L’identificazione intraoperatoria del nervo è avvenuta nel 99,2% dei casi (1768 nervi a rischio). La percentuale di emitiroidectomie e tiroidectomie totali è passata dal 17% all’84%. Una minima disfunzione delle corde vocali dovuta a edema o ematoma è stata diagnosticata laringoscopicamente nel 2,9% dei casi. Le paresi permanenti(0,8% nel primo anno di studio) sono progressivamente diminuite fino ad attestarsi allo 0,32% complessivamente.
L’introduzione di questa metodica in chirurgia tiroidea è associata a una minore percentuale di paresi del nervo ricorrente anche se la frequenza dei disturbi motori di grado minore non è complessivamente mutata
The H1 Forward Proton Spectrometer at HERA
The forward proton spectrometer is part of the H1 detector at the HERA
collider. Protons with energies above 500 GeV and polar angles below 1 mrad can
be detected by this spectrometer. The main detector components are
scintillating fiber detectors read out by position-sensitive photo-multipliers.
These detectors are housed in so-called Roman Pots which allow them to be moved
close to the circulating proton beam. Four Roman Pot stations are located at
distances between 60 m and 90 m from the interaction point.Comment: 20 pages, 10 figures, submitted to Nucl.Instr.and Method
Optimized pharmacological control over the AAV-Gene-Switch vector for regulable gene therapy.
Gene therapy in its current design is an irreversible process. It cannot be stopped in case of unwanted side effects, nor can expression levels of therapeutics be adjusted to individual patient's needs. Thus, the Gene-Switch (GS) system for pharmacologically regulable neurotrophic factor expression was established for treatment of parkinsonian patients. Mifepristone, the synthetic steroid used to control transgene expression of the GS vector, is an approved clinical drug. However, pharmacokinetics and -dynamics of mifepristone vary considerably between different experimental animal species and depend on age and gender. In humans, but not in any other species, mifepristone binds to a high-affinity plasma carrier protein. We now demonstrate that the formulation of mifepristone can have robust impact on its ability to activate the GS system. Furthermore, we show that a pharmacological booster, ritonavir (Rtv), robustly enhances the pharmacological effect of mifepristone, and allows it to overcome gender- and species-specific pharmacokinetic and -dynamic issues. Most importantly, we demonstrate that the GS vector can be efficiently controlled by mifepristone in the presence of its human plasma carrier protein, α1-acid glycoprotein, in a "humanized" rat model. Thus, we have substantially improved the applicability of the GS vector toward therapeutic use in patients
Colour reconnections in Herwig++
We describe the implementation details of the colour reconnection model in
the event generator Herwig++. We study the impact on final-state observables in
detail and confirm the model idea from colour preconfinement on the basis of
studies within the cluster hadronization model. Moreover, we show that the
description of minimum bias and underlying event data at the LHC is improved
with this model and present results of a tune to available data.Comment: 19 pages, 21 figures, 2 tables. Matches with published versio
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