# A melhor ferramenta para a sua pesquisa, trabalho e TCC!

Página 11 dos resultados de 15310 itens digitais encontrados em 0.006 segundos

## N-Alkyl Urea Hydroxamic Acids as a New Class of Peptide Deformylase Inhibitors with Antibacterial Activity

Fonte: American Society for Microbiology
Publicador: American Society for Microbiology

Tipo: Artigo de Revista Científica

Publicado em /09/2002
Português

Relevância na Pesquisa

16.683899%

Peptide deformylase (PDF) is a prokaryotic metalloenzyme that is essential for bacterial growth and is a new target for the development of antibacterial agents. All previously reported PDF inhibitors with sufficient antibacterial activity share the structural feature of a 2-substituted alkanoyl at the P1′ site. Using a combination of iterative parallel synthesis and traditional medicinal chemistry, we have identified a new class of PDF inhibitors with N-alkyl urea at the P1′ site. Compounds with MICs of ≤4 μg/ml against gram-positive and gram-negative pathogens, including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae, have been identified. The concentrations needed to inhibit 50% of enzyme activity (IC50s) for Escherichia coli Ni-PDF were ≤0.1 μM, demonstrating the specificity of the inhibitors. In addition, these compounds were very selective for PDF, with IC50s of consistently >200 μM for matrilysin and other mammalian metalloproteases. Structure-activity relationship analysis identified preferred substitutions resulting in improved potency and decreased cytotoxity. One of the compounds (VRC4307) was cocrystallized with PDF, and the enzyme-inhibitor structure was determined at a resolution of 1.7 Å. This structural information indicated that the urea compounds adopt a binding position similar to that previously determined for succinate hydroxamates. Two compounds...

Link permanente para citações:

## Factors Affecting Recognition and Disjunction of Chromosomes at Distributive Pairing in Female DROSOPHILA MELANOGASTER. I. Total Length VS. Arm Length

Fonte: PubMed
Publicador: PubMed

Tipo: Artigo de Revista Científica

Publicado em /04/1972
Português

Relevância na Pesquisa

16.683899%

The behavior of a compound metacentric fourth chromosome (see PDF) has been examined to determine whether arm length or total length is the basis for recognition in distributive pairing. Recognition was judged by the frequency with which the (see PDF) nondisjoined from a series of X duplications (Dp), ranging in size from ≤ 0.3 to > 4 times the size of a single fourth chromosome. Dp, (see PDF) nondisjunction was measured in the absence and in the presence of a competitor, a compound metacentric X. In both situations, total length and not arm length, was found to confer the characteristic recognition property to the (see PDF). A comparison of Dp, (see PDF) nondisjunction curves for both the noncompetitive and competitive situations with analogous Dp, 4 curves previously obtained, show the Dp, (see PDF) curves to be similar in shape to those obtained earlier but displaced one unit to the right, corresponding precisely to the difference in size between the (see PDF) and the 4. Rules governing chromosome recognition for acrocentrics were found completely applicable to metacentrics; disjunctive behavior of metacentrics differed from that of acrocentrics in that two arms conferred on a chromosome the capacity to act as the intermediate of a trivalent when size no longer warranted this attribute. This capacity...

Link permanente para citações:

## Synergistic potentiation of D-fraction with vitamin C as possible alternative approach for cancer therapy

Fonte: Dove Medical Press
Publicador: Dove Medical Press

Tipo: Artigo de Revista Científica

Publicado em 30/07/2009
Português

Relevância na Pesquisa

16.683899%

Maitake D-fraction or PDF is the bioactive extract of maitake mushroom (Grifola frondosa) and its active constituent is the protein-bound polysaccharide (proteoglucan), or more specifically known as β-glucan. PDF has been extensively studied and a number of its medicinal potentials/properties have been unveiled and demonstrated. Those include various physiological benefits ranging from immunomodulatory and antitumor activities to treatment for hypertension, diabetes, hypercholesterolemia, viral infections (hepatitis B and human immunodeficiency virus), and obesity. Particularly, two major biological activities of PDF, immunomodulatory and antitumor activities, have been the main target for scientific and clinical research. To demonstrate and confirm such biological activities, numerous studies have been performed in vitro and in vivo or in clinical settings. These studies showed that PDF was indeed capable of modulating immunologic and hematologic parameters, inhibiting or regressing the cancer cell growth, and even improving quality of life of cancer patients. Synergistic potentiation of PDF with vitamin C demonstrated in vitro is rather interesting and may have clinical implication, because such combination therapy appears to help improve the efficacy of currently ongoing cancer therapies. Recently...

Link permanente para citações:

## Portable Document Format File Showing the Surface Models of Cadaver Whole Body

Fonte: The Korean Academy of Medical Sciences
Publicador: The Korean Academy of Medical Sciences

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.683899%

In the Visible Korean project, 642 three-dimensional (3D) surface models have been built from the sectioned images of a male cadaver. It was recently discovered that popular PDF file enables users to approach the numerous surface models conveniently on Adobe Reader. Purpose of this study was to present a PDF file including systematized surface models of human body as the beneficial contents. To achieve the purpose, fitting software packages were employed in accordance with the procedures. Two-dimensional (2D) surface models including the original sectioned images were embedded into the 3D surface models. The surface models were categorized into systems and then groups. The adjusted surface models were inserted to a PDF file, where relevant multimedia data were added. The finalized PDF file containing comprehensive data of a whole body could be explored in varying manners. The PDF file, downloadable freely from the homepage (http://anatomy.co.kr), is expected to be used as a satisfactory self-learning tool of anatomy. Raw data of the surface models can be extracted from the PDF file and employed for various simulations for clinical practice. The technique to organize the surface models will be applied to manufacture of other PDF files containing various multimedia contents.

Link permanente para citações:

## An unbiased Hessian representation for Monte Carlo PDFs

Fonte: Springer Berlin Heidelberg
Publicador: Springer Berlin Heidelberg

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.683899%

We develop a methodology for the construction of a Hessian representation of Monte Carlo sets of parton distributions, based on the use of a subset of the Monte Carlo PDF replicas as an unbiased linear basis, and of a genetic algorithm for the determination of the optimal basis. We validate the methodology by first showing that it faithfully reproduces a native Monte Carlo PDF set (NNPDF3.0), and then, that if applied to Hessian PDF set (MMHT14) which was transformed into a Monte Carlo set, it gives back the starting PDFs with minimal information loss. We then show that, when applied to a large Monte Carlo PDF set obtained as combination of several underlying sets, the methodology leads to a Hessian representation in terms of a rather smaller set of parameters (MC-H PDFs), thereby providing an alternative implementation of the recently suggested Meta-PDF idea and a Hessian version of the recently suggested PDF compression algorithm (CMC-PDFs). The mc2hessian conversion code is made publicly available together with (through LHAPDF6) a Hessian representations of the NNPDF3.0 set, and the MC-H PDF set.

Link permanente para citações:

## Phylogenomic and Biochemical Characterization of Three Legionella pneumophila Polypeptide Deformylases

Fonte: American Society for Microbiology
Publicador: American Society for Microbiology

Tipo: Artigo de Revista Científica

Publicado em /07/2006
Português

Relevância na Pesquisa

16.683899%

Legionella pneumophila is a gram-negative facultative intracellular human pathogen that can cause fatal Legionnaires' disease. Polypeptide deformylase (PDF) is a novel broad-spectrum antibacterial target, and reports of inhibitors of PDF with potent activities against L. pneumophila have been published previously. Here, we report the identification of not one but three putative pdf genes, pdfA, pdfB, and pdfC, in the complete genome sequences of three strains of L. pneumophila. Phylogenetic analysis showed that L. pneumophila PdfA is most closely related to the commonly known γ-proteobacterial PDFs encoded by the gene def. PdfB and PdfC are more divergent and do not cluster with any specific bacterial or eukaryotic PDF. All three putative pdf genes from L. pneumophila strain Philadelphia 1 have been cloned, and their encoded products have been overexpressed in Escherichia coli and purified. Enzymatic characterization shows that the purified PDFs with Ni2+ substituted are catalytically active and able to remove the N-formyl group from several synthetic polypeptides, although they appear to have different substrate specificities. Surprisingly, while PdfA and PdfB with Zn2+ substituted are much less active than the Ni2+ forms of each enzyme...

Link permanente para citações:

## Mercado de Trabalho: Conjuntura e Análise: n. 17, nov. 2001

Fonte: Instituto de Pesquisa Econômica Aplicada (Ipea)
Publicador: Instituto de Pesquisa Econômica Aplicada (Ipea)

Tipo: Mercado de trabalho: conjuntura e análise

Português

Relevância na Pesquisa

16.683899%

O boletim Mercado de trabalho: conjuntura e análise tem periodicidade semestral e traz uma análise conjuntural do Mercado de trabalho, acompanhada de indicadores e seções temáticas que abordam tanto considerações mais técnicas como questões de cunho político-institucional.; n. 17, ca. 30 p.; parte 1: Apresentação, arquivo pdf; parte 2: Trabalho decente e flexibilização trabalhista no Brasil, arquivo pdf; parte 3: Trabalho decente: as premissas e a vontade de avançar, arquivo pdf; parte 4: Funcionamento dos mercados e qualidade do trabalho, arquivo pdf; parte 5: Análise do mercado de trabalho, arquivo pdf; parte 6: Nota técnica: O trabalho doméstico infanto-juvenil no Brasil, arquivo pdf; parte 7: Nota técnica: Os jovens brasileiros no mercado de trabalho, arquivo pdf

Link permanente para citações:

## Mercado de Trabalho: Conjuntura e Análise: n. 15, fev. 2001

Fonte: Instituto de Pesquisa Econômica Aplicada (Ipea)
Publicador: Instituto de Pesquisa Econômica Aplicada (Ipea)

Tipo: Mercado de trabalho: conjuntura e análise

Português

Relevância na Pesquisa

16.683899%

O boletim Mercado de trabalho: conjuntura e análise tem periodicidade semestral e traz uma análise conjuntural do Mercado de trabalho, acompanhada de indicadores e seções temáticas que abordam tanto considerações mais técnicas como questões de cunho político-institucional.; n. 15, ca. 30 p.; parte 1: Apresentação, arquivo pdf; parte 2: A OIT e o trabalho seguro, arquivo pdf; parte 3: A importância de ações efetivas no combate aos acidentes no trabalho, arquivo pdf; parte 4: A reforma do seguro acidentário, arquivo pdf; parte 5: Trabalho é vida, arquivo pdf; parte 6: Análise do mercado de trabalho, arquivo pdf; parte 7: Nota técnica: Os incentivos adversos dos programas de proteção ao trabalhador no Brasil, arquivo pdf

Link permanente para citações:

## Mercado de Trabalho: Conjuntura e Análise: n. 7, fev. 1998

Fonte: Instituto de Pesquisa Econômica Aplicada (Ipea)
Publicador: Instituto de Pesquisa Econômica Aplicada (Ipea)

Tipo: Mercado de trabalho: conjuntura e análise

Português

Relevância na Pesquisa

16.683899%

O boletim Mercado de trabalho: conjuntura e análise tem periodicidade semestral e traz uma análise conjuntural do Mercado de trabalho, acompanhada de indicadores e seções temáticas que abordam tanto considerações mais técnicas como questões de cunho político-institucional.; n. 7, ca 30 p.; Parte 1: Editorial, arquivo pdf; Parte 2: Aspectos da política de governo sobre o setor automotivo, arquivo pdf; Parte 3: Emprego e competitividade no setor automotivo: questões e políticas, arquivo pdf; Parte 4: Panorama geral, arquivo pdf; Parte 5: Conjuntura macroeconômica, arquivo pdf; Parte 6: Análise do mercado de trabalho, arquivo pdf; Parte 7: Produto, emprego e produtividade industriais: o que se pode aprender das novas contas nacionais, arquivo pdf

Link permanente para citações:

## Evolution of column density distributions within Orion~A

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 20/04/2015
Português

Relevância na Pesquisa

16.683899%

We compare the structure of star-forming molecular clouds in different
regions of Orion A to determine how the column density probability distribution
function (N-PDF) varies with environmental conditions such as the fraction of
young protostars. A correlation between the N-PDF slope and Class 0 protostar
fraction has been previously observed in a low-mass star-formation region
(Perseus) by Sadavoy; here we test if a similar correlation is observed in a
high-mass star-forming region. We use Herschel data to derive a column density
map of Orion A. We use the Herschel Orion Protostar Survey catalog for accurate
identification and classification of the Orion A young stellar object (YSO)
content, including the short-lived Class 0 protostars (with a $\sim$ 0.14 Myr
lifetime). We divide Orion A into eight independent 13.5 pc$^2$ regions; in
each region we fit the N-PDF distribution with a power-law, and we measure the
fraction of Class 0 protostars. We use a maximum likelihood method to measure
the N-PDF power-law index without binning. We find that the Class 0 fraction is
higher in regions with flatter column density distributions. We test the
effects of incompleteness, YSO misclassification, resolution, and pixel-scale.
We show that these effects cannot account for the observed trend. Our
observations demonstrate an association between the slope of the power-law
N-PDF and the Class 0 fractions within Orion A. Various interpretations are
discussed including timescales based on the Class 0 protostar fraction assuming
a constant star-formation rate. The observed relation suggests that the N-PDF
can be related to an "evolutionary state" of the gas. If universal...

Link permanente para citações:

## On the Density Probability Function of Galactic Gas. I. Numerical Simulations and the Significance of the Polytropic Index

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 07/10/1997
Português

Relevância na Pesquisa

16.715276%

We investigate the form of the one-point probability distribution function
(pdf) for the density field of the interstellar medium using numerical
simulations that successively reduce the number of physical processes included.
Two-dimensional simulations of self-gravitating supersonic MHD and hydrodynamic
turbulence, and of decaying Burgers turbulence, produce in all cases
filamentary density structures and a power-law density pdf with logarithmic
slope around -1.7. This suggests that the functional form of the pdf and the
general filamentary morphology are the signature of the nonlinear advection
operator. These results do not support previous claims that the pdf is
lognormal. A series of 1D simulations of forced supersonic polytropic
turbulence is used to resolve the discrepancy. They suggest that the pdf is
lognormal only for effective polytropic indices $\gamma=1$ (or nearly lognormal
for $\gamma\not=1$ if the Mach number is sufficiently small), while power laws
develop at high densities if $\gamma<1$. We evaluate the polytropic index for
conditions relevant to the cool interstellar medium using published cooling
functions and different heating sources, finding that a lognormal pdf may occur
at densities between 10$^3$ and at least 10$^4$ cm$^{-3}$. Several applications
are examined. First...

Link permanente para citações:

## Turbulence-Induced Relative Velocity of Dust Particles III: The Probability Distribution

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 03/07/2014
Português

Relevância na Pesquisa

16.683899%

Motivated by its important role in the collisional growth of dust particles
in protoplanetary disks, we investigate the probability distribution function
(PDF) of the relative velocity of inertial particles suspended in turbulent
flows. Using the simulation from our previous work, we compute the relative
velocity PDF as a function of the friction timescales, tau_p1 and tau_p2, of
two particles of arbitrary sizes. The friction time of particles included in
the simulation ranges from 0.1 tau_eta to 54T_L, with tau_eta and T_L the
Kolmogorov time and the Lagrangian correlation time of the flow, respectively.
The relative velocity PDF is generically non-Gaussian, exhibiting fat tails.
For a fixed value of tau_p1, the PDF is the fattest for equal-size particles
(tau_p2~tau_p1), and becomes thinner at both tau_p2tau_p1.
Defining f as the friction time ratio of the smaller particle to the larger
one, we find that, at a given f in 1/2>T_L). These features
are successfully explained by the Pan & Padoan model. Using our simulation data
and some simplifying assumptions...

Link permanente para citações:

## An Unbiased Hessian Representation for Monte Carlo PDFs

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.683899%

We develop a methodology for the construction of a Hessian representation of
Monte Carlo sets of parton distributions, based on the use of a subset of the
Monte Carlo PDF replicas as an unbiased linear basis, and of a genetic
algorithm for the determination of the optimal basis. We validate the
methodology by first showing that it faithfully reproduces a native Monte Carlo
PDF set (NNPDF3.0), and then, that if applied to Hessian PDF set (MMHT14) which
was transformed into a Monte Carlo set, it gives back the starting PDFs with
minimal information loss. We then show that, when applied to a large Monte
Carlo PDF set obtained as combination of several underlying sets, the
methodology leads to a Hessian representation in terms of a rather smaller set
of parameters (CMC-H PDFs), thereby providing an alternative implementation of
the recently suggested Meta-PDF idea and a Hessian version of the recently
suggested PDF compression algorithm (CMC-PDFs). The mc2hessian conversion code
is made publicly available together with (through LHAPDF6) a Hessian
representations of the NNPDF3.0 set, and the CMC-H PDF set.; Comment: 27 pages, 17 figures; v2: replaced plots in Fig.1 which had a
conflict with google chrome inline viewer; v3: final version...

Link permanente para citações:

## Joint modeling of the probability distribution and power spectrum of the Lya forest: comparison with observations at z=3

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.683899%

We presents results of joint modeling of the probability distribution
function (PDF) and the one-dimensional power spectrum (PS) of the Lya forest
flux decrement. The sensitivity of these statistical measures to the shape and
amplitude of the linear matter power spectrum is investigated using two
variants of the LCDM cosmology. In the first model, the linear power spectrum
has a scale-invariant spectral index, whereas in the second, it has a negative
running index (RSI). We generate mock catalogs of QSO spectra, and compare
their statistical properties to those of the observations at z=3. We perform a
joint fit of the power spectrum and PDF. A scale-invariant model with
\sigma_8=0.9 matches well the data if the mean IGM temperature is T\leq 15000K.
For higher temperature, it tends to overestimate the flux power spectrum over
scales k < 0.01s/km. The discrepancy is less severe when the PS alone is
fitted. However, models matching the PS alone do not yield a good fit to the
PDF. A joint analysis of the flux PS and PDF tightens the constraints on the
model parameters and reduces systematic biases. The RSI model is consistent
with the observed PS and PDF only if the temperature is T\geq 20000K. The best
fit models reproduce the slope and normalisation of the column density
distribution...

Link permanente para citações:

## Proton structure at the LHC

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 02/11/2014
Português

Relevância na Pesquisa

16.683899%

A determination of Parton Distribution Functions (PDFs) from a global fit to
a dataset including measurements from the LHC has been performed. The
determinations have been carried out according to the NNPDF methodology,
leading to a fit minimising parametrisation bias and with an accurate account
of PDF uncertainty. In this thesis the importance of QCD measurements at the
LHC to PDF extraction are discussed, and we summarise some of the technical
difficulties in their inclusion into PDF fits. A number of methods are
presented that permit the efficient inclusion of these observables into PDF
determinations. Firstly a Bayesian reweighting procedure taking advantage of
the Monte Carlo representation of PDF uncertainties in NNPDF sets is discussed,
which is demonstrated by a study of the impact of early W production asymmetry
measurements from ATLAS, CMS and LHCb upon an earlier PDF set. A package for
the fast computation of observables in an automated NLO framework is presented,
providing an interface between Monte Carlo event generators and NLO
interpolation tools. Finally, a method of combining PDF evolution with
interpolating codes for hadronic observable computation is described. This
method largely overcomes the computational difficulties in performing fast
perturbative QCD predictions for collider observables. The method has been
applied to the determination of PDFs from a global dataset including vector
boson production data from LHCb...

Link permanente para citações:

## The Lyman alpha forest flux probability distribution at z>3

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.715276%

We present a measurement of the Lyman alpha flux probability distribution
function (PDF) measured from a set of eight high resolution quasar spectra with
emission redshifts at 3.3 < z < 3.8. We carefully study the effect of metal
absorption lines on the shape of the PDF. Metals have a larger impact on the
PDF measurements at lower redshift, where there are fewer Lyman alpha
absorption lines. This may be explained by an increase in the number of metal
lines which are blended with Lyman alpha absorption lines toward higher
redshift, but may also be due to the presence of fewer metals in the
intergalactic medium with increasing lookback time. We also provide a new
measurement of the redshift evolution of the effective optical depth, tau_eff,
at 2.8 < z < 3.6, and find no evidence for a deviation from a power law
evolution in the log(tau_eff)-log(1+z) plane. The flux PDF measurements are
furthermore of interest for studies of the thermal state of the intergalactic
medium (IGM) at z ~ 3 . By comparing the PDF to state-of-the-art cosmological
hydrodynamical simulations, we place constraints on the temperature of the IGM
and compare our results with previous measurements of the PDF at lower
redshift. At redshift z=3, our new PDF measurements are consistent with an
isothermal temperature-density relation...

Link permanente para citações:

## Towards a separation of the elements in turbulence via the analyses within MPDFT

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 18/11/2011
Português

Relevância na Pesquisa

16.715276%

#Condensed Matter - Statistical Mechanics#Physics - Data Analysis, Statistics and Probability#Physics - Fluid Dynamics

The PDFs for energy dissipation rates created in a high resolution from
$4096^3$ DNS for fully developed turbulence are analyzed in a high precision
with the PDF derived within the formula of multifractal probability density
function theory (MPDFT). MPDFT is a statistical mechanical ensemble theory
constructed in order to analyze intermittent phenomena through the experimental
PDFs with fat-tail. By making use of the obtained w-PDFs created from the whole
of the DNS region, analyzed for the first time are the two partial PDFs, i.e.,
the max-PDF and the min-PDF which are, respectively, taken out from the partial
DNS regions of the size $512^3$ with maximum and minimum enstropy. The main
information for the partial PDFs are the following. One can find a w-PDF whose
tail part can adjust the slope of the tail-part of a max-PDF with appropriate
magnification factor. The value of the point at which the w-PDF multiplied by
the magnification factor starts to overlap the tail part of the max-PDF
coincides with the value of the connection point for the theoretical w-PDF. The
center part of the min-PDFs can be adjusted quite accurately by the scaled
w-PDFs with a common scale factor.; Comment: 15 pages, 16 figures, 1 table. The contents of the paper is based on
the invited talk given at SigmaPhi 2011 at Larnaca in Cyprus

Link permanente para citações:

## The Gamma-Ray-Flux Probability Distribution Function from Galactic Halo Substructure

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.683899%

One of the targets of the recently launched Fermi Gamma-ray Space Telescope
is a diffuse gamma-ray background from dark-matter annihilation or decay in the
Galactic halo. N-body simulations and theoretical arguments suggest that the
dark matter in the Galactic halo may be clumped into substructure, rather than
smoothly distributed. Here we propose the gamma-ray-flux probability
distribution function (PDF) as a probe of substructure in the Galactic halo. We
calculate this PDF for a phenomenological model of halo substructure and
determine the regions of the substructure parameter space in which the PDF may
be distinguished from the PDF for a smooth distribution of dark matter. In
principle, the PDF allows a statistical detection of substructure, even if
individual halos cannot be detected. It may also allow detection of
substructure on the smallest microhalo mass scales, $\sim M_\oplus$, for
weakly-interacting massive particles (WIMPs). Furthermore, it may also provide
a method to measure the substructure mass function. However, an analysis that
assumes a typical halo substructure model and a conservative estimate of the
diffuse background suggests that the substructure PDF may not be detectable in
the lifespan of Fermi in the specific case that the WIMP is a neutralino.
Nevertheless...

Link permanente para citações:

## A meta-analysis of parton distribution functions

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

16.715276%

A "meta-analysis" is a method for comparison and combination of
nonperturbative parton distribution functions (PDFs) in a nucleon obtained with
heterogeneous procedures and assumptions. Each input parton distribution set is
converted into a "meta-parametrization" based on a common functional form. By
analyzing parameters of the meta-parametrizations from all input PDF ensembles,
a combined PDF ensemble can be produced that has a smaller total number of PDF
member sets than the original ensembles. The meta-parametrizations simplify the
computation of the PDF uncertainty in theoretical predictions and provide an
alternative to the 2010 PDF4LHC convention for combination of PDF
uncertainties. As a practical example, we construct a META ensemble for
computation of QCD observables at the Large Hadron Collider using the
next-to-next-to-leading order PDF sets from CTEQ, MSTW, and NNPDF groups as the
input. The META ensemble includes a central set that reproduces the average of
LHC predictions based on the three input PDF ensembles and Hessian eigenvector
sets for computing the combined PDF+$\alpha_s$ uncertainty at a common QCD
coupling strength of 0.118.; Comment: version to appear on JHEP

Link permanente para citações:

## Measurement of the Inclusive Isolated Prompt Photon Production Cross Section at the Tevatron using the CDF Detector

Fonte: [Barcelona] : Universitat Autònoma de Barcelona,
Publicador: [Barcelona] : Universitat Autònoma de Barcelona,

Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion
Formato: application/pdf

Publicado em //2011
Português

Relevância na Pesquisa

16.715276%

Esta tesis presenta la medida de la sección eficaz de producción de fotones inmediatos con <1.0, pT > 30 GeV y asilamiento < 2 GeV usando 2.5 fb-1 de datos tomados por el detector CDF entre febrero de 2002 y agosto de 2007. La medida incluye 6 veces más datos que el último resultado publicado al momento de su realización, extendiendo el rango de pT cubierto por la misma en 100 GeV. La sección eficaz se mide para fotones de hasta 400 GeV, y testea las predicciones teóricas sobre 6 órdenes de magnitud, un orden de magnitud más que en resultados previos. La medida de la sección eficaz de fotones inmediatos ofrece una oportunidad única para poner a prueba las técnicas de indentificación de fotones en Física de Altas Energías. En esta tesis, presentamos una nueva técnica para suprimir el ruido de fondo irreducible que viene de los fotones producidos por la desintegracion de mesones. El método consiste en ajustar la variable de aislamiento energetico del fotón en el calorímetro a la suma de las formas esperadas (templates) para esta variable para la señal y para el ruido de fondo, en diferentes rangos en el momento transverso del fotón. El método de las templates es simple y está basado únicamente en información del calorímetro. Además...

Link permanente para citações: