2,307 research outputs found
A Squid-Based Beam Current Monitor For FAIR
A Cryogenic Current Comparator (CCC) wasdeveloped for the upcoming FAIR-Project, providing anon-destructive online monitoring of the beam current inthe nA-range. The CCC was optimized for a lowestpossible noise-limited current resolution together with ahigh system bandwidth. Therefore, the low temperatureproperties of ferromagnetic core materials used in thepick-up coil were investigated and differentSuperconducting Quantum Interference Device (SQUID)-systems were tested.In this contribution we present results of the completedCryogenic Current Comparator for FAIR working in alaboratory environment, regarding the improvements inresolution and bandwidth due to the use of suitableferromagnetic core materials and optimized SQUIDsystemcomponents
Immunogenicity Studies in Carnivores Using a Rabies Virus Construct with a Site-Directed Deletion in the Phosphoprotein
Different approaches have been applied to develop highly attenuated rabies virus vaccines for oral vaccination of mesocarnivores. One prototype vaccine construct is SAD dIND1, which contains a deletion in the P-gene severely limiting the inhibition of type-1 interferon induction. Immunogenicity studies in foxes and skunks were undertaken to investigate whether this highly attenuated vaccine would be more immunogenic than the parental SAD B19 vaccine strain. In foxes, it was demonstrated that SAD dIND1 protected the animals against a rabies infection after a single oral dose, although virus neutralizing antibody titres were lower than in foxes orally vaccinated with the SAD B19 virus as observed in previous experiments. In contrast, skunks receiving 107.5 FFU SAD dIND1 did not develop virus neutralizing antibodies and were not protected against a subsequent rabies infection
Systematic 1/M Expansion for Spin 3/2 Particles
Starting from a relativistic formulation of the pion-nucleon-delta system,
the most general structure of 1/M corrections for a heavy baryon chiral
lagrangian including spin 3/2 resonances is given. The heavy components of
relativistic nucleons and delta fields are integrated out and their
contributions to the next-to-leaing order lagrangians are constructed
explicitly. The effective theory obtained admits a systematic expansion in
terms of soft momenta, the pion mass and the delta-nucleon mass
difference . As an application, we consider neutral pion
photoproduction at threshold to third order in this small scale expansion.Comment: Revised version of original submissio
Supplements to article: A novel transcription complex that selectively modulates apoptosis of breast cancer cells through regulation of FASTKD2
The materials provided here are supplemental tables and figures to an
article to be published in 'Molecular and Cellular Biology.'(This refers to the article.) We previously reported that expression of
NRIF3 (Nuclear Receptor Interacting Factor-3) rapidly and selectively
leads to apoptosis of breast cancer cells. DIF-1 (a.k.a IRF-2BP2), the
cellular target of NRIF3, was identified as a transcriptional repressor
and DIF-1 knockdown leads to apoptosis of breast cancer cells but not
other cell types. Here, we identify IRF2BP1 (Interferon Regulatory
Factor-2 Binding Protein 1) and EAP1 (Enhanced At Puberty 1) as
important components of the DIF-1 complex mediating both complex
stability and transcriptional repression. This interaction of DIF-1,
IRF2BP1, and EAP1 occurs through the conserved C4 zinc-fingers of these
proteins. Microarray studies were carried out in breast cancer cell
lines engineered to conditionally and rapidly increase the levels of the
Death Domain region of NRIF3 (DD1). The DIF-1 complex was found to
repress FASTKD2, a putative pro-apoptotic gene, in breast cancer cells
and to bind to the FASTKD2 gene by chromatin immunoprecipitation.
FASTKD2 knockdown prevents apoptosis of breast cancer cells from NRIF3
expression or DIF-1 knockdown while expression of FASTKD2 leads to
apoptosis of both breast and non-breast cancer cells. Thus, regulation
of FASTKD2 by NRIF3 and the DIF-1 complex acts as a novel death switch
that selectively modulates apoptosis in breast cancer
The mesospheric inversion layer and sprites
The vertical structure of temperature observed by SABER (Sounding of
Atmosphere using Broadband Emission Radiometry) aboard TIMED (Thermosphere,
Ionosphere, Mesosphere Energetics and Dynamics) and sprites observations made
during the Eurosprite 2003 to 2007 observational campaign were analyzed. Sprite
observations were made at two locations in France, namely Puy de Dome in the
French Massif Central and at the Pic du Midi in the French Pyrenees. It is
observed that the vertical structure of temperature shows evidence for a
Mesospheric Inversion Layer (MIL) on those days on which sprites were observed.
A few events are also reported in which sprites were not recorded, although
there is evidence of a MIL in the vertical structure of the temperature. It is
proposed that breaking gravity waves produced by convective thunderstorms
facilitate the production of (a) sprites by modulating the neutral air-density
and (b) MILs via the deposition of energy. The same proposition has been used
to explain observations of lightings as well as both MILs and lightning arising
out of deep convections.Comment: 34 pages, 5figures. Accepted in Journal of Geophysical Research, US
Relations among Zero Momentum Correlators for Heavy-Light Systems in QCD
Relations connecting various zero momentum correlators of interpolating
fields for pseudoscalar and scalar channel, containing one heavy and one light
quark field, are derived from the Euclidean space formulation of the QCD
functional integral. These relations may serve as constraints on the
phenomenological models or approaches motivated from QCD, and suggest a method
to extract the chiral quark condensates. It is also found that the correlator
for pseudoscalar channel differs from that for scalar channel even in the large
heavy quark mass limit.Comment: 9 pages in ReVTeX, UMD preprint #94-14
Electroweak Gauge-Boson Production at Small q_T: Infrared Safety from the Collinear Anomaly
Using methods from effective field theory, we develop a novel, systematic
framework for the calculation of the cross sections for electroweak gauge-boson
production at small and very small transverse momentum q_T, in which large
logarithms of the scale ratio M_V/q_T are resummed to all orders. These cross
sections receive logarithmically enhanced corrections from two sources: the
running of the hard matching coefficient and the collinear factorization
anomaly. The anomaly leads to the dynamical generation of a non-perturbative
scale q_* ~ M_V e^{-const/\alpha_s(M_V)}, which protects the processes from
receiving large long-distance hadronic contributions. Expanding the cross
sections in either \alpha_s or q_T generates strongly divergent series, which
must be resummed. As a by-product, we obtain an explicit non-perturbative
expression for the intercept of the cross sections at q_T=0, including the
normalization and first-order \alpha_s(q_*) correction. We perform a detailed
numerical comparison of our predictions with the available data on the
transverse-momentum distribution in Z-boson production at the Tevatron and LHC.Comment: 34 pages, 9 figure
On the Structure of Infrared Singularities of Gauge-Theory Amplitudes
A closed formula is obtained for the infrared singularities of dimensionally
regularized, massless gauge-theory scattering amplitudes with an arbitrary
number of legs and loops. It follows from an all-order conjecture for the
anomalous-dimension matrix of n-jet operators in soft-collinear effective
theory. We show that the form of this anomalous dimension is severely
constrained by soft-collinear factorization, non-abelian exponentiation, and
the behavior of amplitudes in collinear limits. Using a diagrammatic analysis,
we demonstrate that these constraints imply that to three-loop order the
anomalous dimension involves only two-parton correlations, with the possible
exception of a single color structure multiplying a function of conformal cross
ratios depending on the momenta of four external partons, which would have to
vanish in all two-particle collinear limits. We argue that such a function does
not appear at three-loop order, and that the same is true in higher orders. Our
formula predicts Casimir scaling of the cusp anomalous dimension to all orders
in perturbation theory, and we explicitly check that the constraints exclude
the appearance of higher Casimir invariants at four loops. Using known results
for the quark and gluon form factors, we derive the three-loop coefficients of
the 1/epsilon^n pole terms (with n=1,...,6) for an arbitrary n-parton
scattering amplitude in massless QCD. This generalizes Catani's two-loop
formula proposed in 1998.Comment: 46 pages, 9 figures; v2: improved treatment of collinear limits,
references added; v3: improved discussion of non-abelian exponentiation,
references updated; v4: typo in eq. (17) fixed, references updated; v5:
additional term in (17
Soft-Collinear Messengers: A New Mode in Soft-Collinear Effective Theory
It is argued that soft-collinear effective theory for processes involving
both soft and collinear partons, such as exclusive B-meson decays, should
include a new mode in addition to soft and collinear fields. These
"soft-collinear messengers" can interact with both soft and collinear particles
without taking them far off-shell. They thus can communicate between the soft
and collinear sectors of the theory. The relevance of the new mode is
demonstrated with an explicit example, and the formalism incorporating the
corresponding quark and gluon fields into the effective Lagrangian is
developed.Comment: 22 pages, 5 figures. Extended Section 6, clarifying the relevance of
different types of soft-collinear interaction
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