3,682 research outputs found
Searches for Majorana Neutrinos and Direct Searches for Exotics at LHCb
These proceedings present the LHCb results on Majorana neutrino searches and
direct production of exotic particles using the data collected during Run I of
LHC. For the former, Majorana neutrinos are searched for both on-shell and
off-shell in and decays to final states with two same-sign muons. For
the latter, different types of new particles are studied profiting the unique
coverage of LHCb with respect to other detectors.Comment: 9 pages, 27 figures. To be published in the LISHEP 2015 proceeding
Muon Identification in the LHCb experiment
A short summary of the LHCb muon identification procedure is given in this
article. First, the muon system of LHCb is presented, together with some
examples of physics measurements of the experiment where the muon
identification is crucial. Then, the muon identification algorithm is
introduced in three single steps. With this, the efficiency vs.
misidentification rate is shown for MC simulated data. The way this method will
be calibrated with real data is also seen. Finally, some preliminary muon
identification results with proton-proton collisions at sqrt(s) = 900 GeV are
presented.Comment: Proceedings for the Moriond 2010 E
Novel Hemizygous IL2RG p.(Pro58Ser) Mutation Impairs IL-2 Receptor Complex Expression on Lymphocytes Causing X-Linked Combined Immunodeficiency
Hypomorphic IL2RG mutations may lead to milder phenotypes than X-SCID, named variably as atypical X-SCID or X-CID. We report an 11-year-old boy with a novel c. 172C>T;p.(Pro58Ser) mutation in IL2RG, presenting with atypical X-SCID phenotype. We also review the growing number of hypomorphic IL2RG mutations causing atypical X-SCID. We studied the patient's clinical phenotype, B, T, NK, and dendritic cell phenotypes, IL2RG and CD25 cell surface expression, and IL-2 target gene expression, STAT tyrosine phosphorylation, PBMC proliferation, and blast formation in response to IL-2 stimulation, as well as protein-protein interactions of the mutated IL2RG by BioID proximity labeling. The patient suffered from recurrent upper and lower respiratory tract infections, bronchiectasis, and reactive arthritis. His total lymphocyte counts have remained normal despite skewed T and B cells subpopulations, with very low numbers of plasmacytoid dendritic cells. Surface expression of IL2RG was reduced on his lymphocytes. This led to impaired STAT tyrosine phosphorylation in response to IL-2 and IL-21, reduced expression of IL-2 target genes in patient CD4+ T cells, and reduced cell proliferation in response to IL-2 stimulation. BioID proximity labeling showed aberrant interactions between mutated IL2RG and ER/Golgi proteins causing mislocalization of the mutated IL2RG to the ER/Golgi interface. In conclusion, IL2RG p.(Pro58Ser) causes X-CID. Failure of IL2RG plasma membrane targeting may lead to atypical X-SCID. We further identified another carrier of this mutation from newborn SCID screening, lost to closer scrutiny.Peer reviewe
The Callias Index Formula Revisited
We revisit the Callias index formula for Dirac-type operators in odd
space dimension , and prove that \begin{align}
\text{ind} \, (L)
=\bigg(\frac{i}{8\pi}\bigg)^{\frac{n-1}{2}}\frac{1}{2(\frac{n-1}{2})!}
\lim_{\Lambda \to\infty}\frac{1}{\Lambda }\sum_{i_{1},\dots,i_{n} = 1}^n
\varepsilon_{i_{1}\dots i_{n}}
\int_{\Lambda S_{n-1}}\text{tr}_{\mathbb{C}^d}\,
(U(x)(\partial_{i_{1}}U)(x)\dots
(\partial_{i_{n-1}}U)(x)) x_{i_{n}}\, d^{n-1} \sigma(x), \, (*) \end{align}
where and in
is of the form where with
elements of the Euclidean Dirac algebra, and or . Here is assumed to satisfy the following conditions:
\begin{align} & \Phi\in C_{b}^{2}\big(\mathbb{R}^{n};\mathbb{C}^{d\times
d}\big), \quad d \in \mathbb{N}, \\ & \Phi(x)=\Phi(x)^{*}, \end{align} there
exists , such that and there exists
such that for all , , there is
such that These conditions on render a
Fredholm operator, and appear to be the most general conditions known to date
for which Callias' index formula has been derived.
Generalizations of the index formula to certain classes of non-Fredholm
operators invoking the (generalized) Witten index are also discussed.Comment: 135 pages, we extended section 3 and removed a number of typos
throughout this manuscrip
Curse of dimensionality reduction in max-plus based approximation methods: theoretical estimates and improved pruning algorithms
Max-plus based methods have been recently developed to approximate the value
function of possibly high dimensional optimal control problems. A critical step
of these methods consists in approximating a function by a supremum of a small
number of functions (max-plus "basis functions") taken from a prescribed
dictionary. We study several variants of this approximation problem, which we
show to be continuous versions of the facility location and -center
combinatorial optimization problems, in which the connection costs arise from a
Bregman distance. We give theoretical error estimates, quantifying the number
of basis functions needed to reach a prescribed accuracy. We derive from our
approach a refinement of the curse of dimensionality free method introduced
previously by McEneaney, with a higher accuracy for a comparable computational
cost.Comment: 8pages 5 figure
Global existence for defocusing cubic NLS and Gross-Pitaevskii equations in three dimensional exterior domains
We prove global wellposedness in the energy space of the defocusing cubic
nonlinear Schroedinger and Gross-Pitaevskii equations on the exterior of a
non-trapping domain in dimension 3. The main ingredient is a Strichartz
estimate obtained combining a semi-classical Strichartz estimate with a
smoothing effect on exterior domains
Measurement of resonant and CP components in B0s→J/ψπ+π− decays
Structure of the decay B̄s0→J/ψπ+π- is studied using data corresponding to 3fb-1 of integrated luminosity from pp collisions produced by the LHC and collected by the LHCb detector. Five interfering π+π- states are required to describe the decay: f0(980),f0(1500),f0(1790),f2(1270), and f2′(1525). An alternative model including these states and a nonresonant J/ψπ+π- component also provides a good description of the data. Based on the different transversity components measured for the spin-2 intermediate states, the final state is found to be compatible with being entirely CP odd. The CP-even part is found to be <2.3% at a 95% confidence level. The f0(500) state is not observed, allowing a limit to be set on the absolute value of the mixing angle with the f0(980) of <7.7° at a 90% confidence level, consistent with a tetraquark interpretation of the f0(980) substructure
Novel Hemizygous IL2RG p.(Pro58Ser) Mutation Impairs IL-2 Receptor Complex Expression on Lymphocytes Causing X-Linked Combined Immunodeficiency
Hypomorphic IL2RG mutations may lead to milder phenotypes than X-SCID, named variably as atypical X-SCID or X-CID. We report an 11-year-old boy with a novel c. 172C>T;p.(Pro58Ser) mutation in IL2RG, presenting with atypical X-SCID phenotype. We also review the growing number of hypomorphic IL2RG mutations causing atypical X-SCID. We studied the patient's clinical phenotype, B, T, NK, and dendritic cell phenotypes, IL2RG and CD25 cell surface expression, and IL-2 target gene expression, STAT tyrosine phosphorylation, PBMC proliferation, and blast formation in response to IL-2 stimulation, as well as protein-protein interactions of the mutated IL2RG by BioID proximity labeling. The patient suffered from recurrent upper and lower respiratory tract infections, bronchiectasis, and reactive arthritis. His total lymphocyte counts have remained normal despite skewed T and B cells subpopulations, with very low numbers of plasmacytoid dendritic cells. Surface expression of IL2RG was reduced on his lymphocytes. This led to impaired STAT tyrosine phosphorylation in response to IL-2 and IL-21, reduced expression of IL-2 target genes in patient CD4+ T cells, and reduced cell proliferation in response to IL-2 stimulation. BioID proximity labeling showed aberrant interactions between mutated IL2RG and ER/Golgi proteins causing mislocalization of the mutated IL2RG to the ER/Golgi interface. In conclusion, IL2RG p.(Pro58Ser) causes X-CID. Failure of IL2RG plasma membrane targeting may lead to atypical X-SCID. We further identified another carrier of this mutation from newborn SCID screening, lost to closer scrutiny
Investigation of Combined Effects of Xanthan Gum,Sodium Dodecyl Sulphate, and Salt on Some Physicochemical Properties of Their Mixtures Using a Response Surface Method
Aqueous solutions containing sodium dodecyl sulphate, xanthan gum, and salt were characterized by ionic conductivity, viscosity, and surface tension methods. A preliminary experimental study was performed to evaluate the effect of the mixture compositions on the surface behavior of the mixed polymer/surfactant systems under different solution conditions. An experimental design using response surface method (RSM) was then applied to assess factors interactions and empirical models regarding the physicochemical responses variables (i.e., conductivity, surface tension and viscosity). The main effects of the three independent factors: SDS concentration (x1), NaCl concentration (x2) and xanthan concentration (x3) were determined using in particular a D-optimal design. The results show an important effect of the factors on responses; they also indicate that the synergetic action of surfactant, electrolyte and biopolymer greatly influences these properties. Analysis of variance (ANOVA) showed high variance coefficient (R 2 ) values, thus, ensuring a satisfactory adjustment of the second-order regression model with the experimental data
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