941 research outputs found
Genexpressionsanalysen an Nierenbiopsien: Die Europäische Renale cDNA Bank - Kröner-Fresenius Biopsiebank
Zusammenfassung: Die Nierenbiopsie und deren histologische Aufarbeitung sind klinische Routine und diagnostischer Goldstandard in der Nephrologie. Neue Methoden ermöglichen an dem gewonnenen Material neben der etablierten Diagnostik auch die umfassende Analyse der Genexpression. Anhand von Ergebnissen einer europäischen Multicenterstudie zur Genexpressionsanalyse an Nierenbiopsien wird gezeigt, dass dieser moderne Ansatz nicht nur die sogenannte Grundlagenforschung bereichert, sondern in Zukunft die Biopsiediagnostik ergänzen könnte. Die Ziele sind hierbei erweiterte Diagnosestellung, spezifischere Therapieentscheidung und individuelle Prognoseabschätzun
Rezidivierende Urolithiasis mit progredienter Niereninsuffizienz
Zusammenfassung: Bei einem 30-jährigen Patienten bestand bei rezidivierender Urolithiasis und progredienter Niereninsuffizienz die initiale Diagnose einer sekundären Hyperoxalurie. Die vertiefte Anamnese sowie neue klinische Aspekte ließen dann eine primäre Hyperoxalurie (PH) vermuten, die molekulargenetisch als PH1 bestätigt werden konnte. Pathogenese, klinischer Verlauf und therapeutische Optionen der PH werden diskutier
Excited Baryon Decay Widths in Large N_c QCD
We study excited baryon decay widths in large N_c QCD. It was suggested
previously that some spin-flavor mixed-symmetric baryon states have strong
couplings of O(N_c^{-1/2}) to nucleons [implying narrow widths of O(1/N_c)], as
opposed to the generic expectation based on Witten's counting rules of an
O(N_c^0) coupling. The calculation obtaining these narrow widths was performed
in the context of a simple quark-shell model. This paper addresses the question
of whether the existence of such narrow states is a general property of large
N_c QCD. We show that a general large N_c QCD analysis does not predict such
narrow states; rather they are a consequence of the extreme simplicity of the
quark model.Comment: 9 page
Electroweak Baryogenesis in the Next to Minimal Supersymmetric Model
In the electroweak phase transition there arises the problem of baryon number
washout by sphaleron transitions, which can be avoided if the phase transition
is strongly enough first order. The minimal supersymmetric standard model has
just two Higgs doublets H1 and H2, while the next to minimal model, NMSSM, has
an additional singlet, N, this latter giving rise to the helpful feature that
the Higgs potential contains a tree level trilinear field term. We use the
tunneling criterion for the existence of a first order electroweak phase
change. A quantitative statistical analysis indicates that with parameters of
the NMSSM satisfying the experimental constraints a strong first order phase
change occurs in about 50% of cases.Comment: 15 pages, plain LaTe
Neutrinos in 5D SO(10) Unification
We study neutrino physics in a 5D supersymmetric SO(10) GUT. We analyze
several different choices for realizing the See-Saw mechanism. We find that the
"natural" scale for the Majorana mass of right-handed neutrinos depends
critically on whether the right-handed neutrinos are located in the bulk or
localized on a brane. In the former case, the effective Majorana mass is
"naturally" of order the compactification scale, about 10^{14} GeV. Note, this
is the value necessary for obtaining a light tau neutrino mass approximately
10^{-2} eV which, within the context of hierarchical neutrino masses, is the
right order of magnitude to explain atmospheric neutrino oscillations. On the
other-hand when the right-handed neutrino is localized on the brane, the
effective Majorana mass is typically larger than the compactification scale.
Nevertheless with small parameters of order 1/10 - 1/30, an effective Majorana
mass of order 10^{14} GeV can be accommodated. We also discuss the constraints
on model building resulting from the different scenarios for locating the
right-handed neutrinos.Comment: 24 page
Classification of protein interaction sentences via gaussian processes
The increase in the availability of protein interaction studies in textual format coupled with the demand for easier access to the key results has lead to a need for text mining solutions. In the text processing pipeline, classification is a key step for extraction of small sections of relevant text. Consequently, for the task of locating protein-protein interaction sentences, we examine the use of a classifier which has rarely been applied to text, the Gaussian processes (GPs). GPs are a non-parametric probabilistic analogue to the more popular support vector machines (SVMs). We find that GPs outperform the SVM and na\"ive Bayes classifiers on binary sentence data, whilst showing equivalent performance on abstract and multiclass sentence corpora. In addition, the lack of the margin parameter, which requires costly tuning, along with the principled multiclass extensions enabled by the probabilistic framework make GPs an appealing alternative worth of further adoption
Excited Baryons in Large N_c QCD Revisited: The Resonance Picture Versus Single-Quark Excitations
We analyze excited baryon properties via a 1/N_c expansion from two
perspectives: as resonances in meson-nucleon scattering, and as single-quark
excitations in the context of a simple quark model. For both types of analysis
one can derive novel patterns of degeneracy that emerge as N_c --> \infty, and
that are shown to be compatible with one another. This helps justify the
single-quark excitation picture and may give some insight into its successes.
We also find that in the large N_c limit one of the S_{11} baryons does not
couple to the pi-N channel but couples to the eta-N channel. This is
empirically observed in the N(1535), which couples very weakly to the pi-N
channel and quite strongly to the eta-N channel. The comparatively strong
coupling of the N(1650) to the pi-N channel and weak coupling to eta-N channel
is also predicted. In the context of the simple quark model picture we
reproduce expressions for mixing angles that are accurate up to O(1/N_c)
corrections and are in good agreement with mixing angles extracted
phenomenologically.Comment: 13 pages, ReVTeX
CP Nonconservation in
CP violation effects in are examined. CP-odd,
-odd and -even observables can both be used to extract information on
the real and imaginary parts of Feynman amplitudes. Two Higgs doublet model
with CP violating phase from neutral Higgs exchange is used to estimate
possible effects.Comment: 9 pages, 4 Figures, Late
1/N Expansion for Exotic Baryons
The 1/N expansion for exotic baryons is developed, and applied to the masses,
meson couplings and decay widths. Masses and widths of the 27 and 35 pentaquark
states in the same tower as the Theta+ are related by spin-flavor symmetry. The
27 and 35 states can decay within the pentaquark tower, as well as to normal
baryons, and so have larger decay widths than the lightest pentaquark Theta.
The 1/N expansion also is applied to baryon exotics containing a single heavy
antiquark. The decay widths of heavy pentaquarks via pion emission, and to
normal baryons plus heavy D^(*),B^(*) mesons are studied, and relations
following from large-N spin-flavor symmetry and from heavy quark symmetry are
derived.Comment: Major additions: plots of widths and branching ratios, discussion of
strong decays of heavy pentaquarks, including consequences of heavy quark
symmetr
Fermion Masses and Gauge Mediated Supersymmetry Breaking from a Single U(1)
We present a supersymmetric model of flavor. A single U(1) gauge group is
responsible for both generating the flavor spectrum and communicating
supersymmetry breaking to the visible sector. The problem of Flavor Changing
Neutral Currents is overcome, in part using an `Effective Supersymmetry'
spectrum among the squarks, with the first two generations very heavy. All
masses are generated dynamically and the theory is completely renormalizable.
The model contains a simple Froggatt-Nielsen sector and communicates
supersymmetry breaking via gauge mediation without requiring a separate
messenger sector. By forcing the theory to be consistent with SU(5) Grand
Unification, the model predicts a large tan beta and a massless up quark. While
respecting the experimental bounds on CP violation in the K-system, the model
leads to a large enhancement of CP violation in B-(B bar) mixing as well as in
B decay amplitudes.Comment: LaTeX, 25 pages, 8 figure
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