2,609 research outputs found
Interstitial cells of Cajal — systematic review
This paper reviews the distribution of interstitial cells of Cajal (ICC) in the human gastrointestinal (GI) tract, based on ultrastructural and immunohistochemical evidence. The distribution and morphology of ICC at each level of the normal GI tracts is addressed from the perspective of their functional significance. Alterations of ICC reported in as well as in GI stromal tumours are reviewed, with emphasis on the place of ICC in the pathophysiology of disease
Towards a consistent Oxfordian–Kimmeridgian global boundary: current state of knowledge
New data are presented in relation to the worldwide definition of the Oxfordian/Kimmeridgian boundary, i.e. the base of the Kimmeridgian Stage. This data, mostly acquired in the past decade, supports the 2006 proposal to make the uniform boundary of the stages in the Flodigarry section at Staffin Bay on the Isle of Skye, northern Scotland. This boundary is based on the Subboreal-Boreal ammonite successions, and it is distinguished by the Pictonia flodigarriensis horizon at the base of the Subboreal Baylei Zone, and which corresponds precisely to the base of the Boreal Bauhini Zone. The boundary lies in the 0.16 m interval (1.24–1.08 m) below bed 36 in sections F6 at Flodigarry and it is thus proposed as the GSSP for the Oxfordian/Kimmeridgian boundary. This boundary is recognized also by other stratigraphical data – palaeontological, geochemical and palaeomagnetic (including its well documented position close to the boundary between magnetozones F3n, and F3r which is placed in the 0.20 m interval – 1.28 m to 1.48 m below bed 36 – the latter corresponding to marine magnetic anomaly M26r).The boundary is clearly recognizable also in other sections of the Subboreal and Boreal areas discussed in the study, including southern England, Pomerania and the Peri-Baltic Syneclise, Russian Platform, Northern Central Siberia, Franz-Josef Land, Barents Sea and Norwegian Sea. It can be recognized also in the Submediterranean-Mediterranean areas of Europe and Asia where it correlates with the boundary between the Hypselum and the Bimmamatum ammonite zones. The changes in ammonite faunas at the boundary of these ammonite zones – mostly of ammonites of the families Aspidoceratidae and Oppeliidae – also enables the recognition of the boundary in the Tethyan and Indo-Pacific areas – such as the central part of the Americas (Cuba, Mexico), southern America, and southern parts of Asia. The climatic and environmental changes near to the Oxfordian/Kimmeridgian boundary discussed in the study relate mostly to the European areas. They show that very unstable environments at the end of the Oxfordian were subsequently replaced by more stable conditions representing a generally warming trend during the earliest Kimmeridgian. The definition of the boundary between the Oxfordian and Kimmeridgian as given in this study results in its wide correlation potential and means that it can be recognized in the different marine successions of the World
Evidence of the Purely Leptonic Decay B- --> tau- nu_tau-bar
We present the first evidence of the decay B- --> tau- nu_tau-bar using 414
fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at
the KEKB asymmetric-energy e+e- collider. Events are tagged by fully
reconstructing one of the B mesons in hadronic modes. We detect the signal with
a significance of 3.5 standard deviations including systematics, and measure
the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79
+0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229
+0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement
of this quantity.Comment: 6 pages, 3 figures, to appear in Physical Review Letter
Search for TeV Scale Physics in Heavy Flavour Decays
The subject of heavy flavour decays as probes for physics beyond the TeV
scale is covered from the experimental perspective. Emphasis is placed on the
more traditional Beyond the Standard Model topics that have potential for
impact in the short term, with the physics explained. We do unabashedly promote
our own phemonenology work.Comment: 10 pages, 9 figures (now fixed); Submitted for the SUSY07 proceeding
Measurement of the near-threshold cross section using initial-state radiation
We report measurements of the exclusive cross section for , where or , in the center-of-mass energy range from the threshold to with initial-state radiation. The
analysis is based on a data sample collected with the Belle detector with an
integrated luminosity of 673 .Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC
The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
The design, construction, and commissioning of the ALICE Time-Projection
Chamber (TPC) is described. It is the main device for pattern recognition,
tracking, and identification of charged particles in the ALICE experiment at
the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and
is operated in a 0.5 T solenoidal magnetic field parallel to its axis.
In this paper we describe in detail the design considerations for this
detector for operation in the extreme multiplicity environment of central
Pb--Pb collisions at LHC energy. The implementation of the resulting
requirements into hardware (field cage, read-out chambers, electronics),
infrastructure (gas and cooling system, laser-calibration system), and software
led to many technical innovations which are described along with a presentation
of all the major components of the detector, as currently realized. We also
report on the performance achieved after completion of the first round of
stand-alone calibration runs and demonstrate results close to those specified
in the TPC Technical Design Report.Comment: 55 pages, 82 figure
Evidence for B to K eta' gamma Decays at Belle
We present the results of a search for the radiative decay (B -> K eta'
gamma) and find evidence for (B^+ -> K^+ eta' gamma) decays at the 3.3 standard
deviation level with a partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x
10e-6, where the first error is statistical and the second systematic. This
measurement is restricted to the region of combined (K eta') invariant mass
less than 3.4GeVc^2. A 90% confidence level upper limit of 6.4 x 10e-6 is
obtained for the decay (B^0 -> K^0 eta' gamma) in the same (K eta') invariant
mass region. These results are obtained from a 605 fb^-1 data sample containing
657 x 10e6 B anti-B pairs collected at the Upsilon(4S) resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider.Comment: 5 pages, 4 figures. Submitted to PRD-RC on 6/8/0
Study of charmonia in four-meson final states produced in two-photon collisions
We report measurements of charmonia produced in two-photon collisions and
decaying to four-meson final states, where the meson is either a charged pion
or a charged kaon. The analysis is based on a 395fb^{-1} data sample
accumulated with the Belle detector at the KEKB electron-positron collider. We
observe signals for the three C-even charmonia eta_c(1S), chi_{c0}(1P) and
chi_{c2}(1P) in the pi^+pi^-pi^+pi^-, K^+K^-pi^+pi^- and K^+K^-K^+K^- decay
modes. No clear signals for eta_c(2S) production are found in these decay
modes. We have also studied resonant structures in charmonium decays to
two-body intermediate meson resonances. We report the products of the
two-photon decay width and the branching fractions, Gamma_{gamma gamma}B, for
each of the charmonium decay modes.Comment: 22 pages, 12 figure
Study of J/psi to p pbar, Lambda Lambdabar and observation of eta_c to Lambda Lambdabar at Belle
We study the baryonic charmonium decays of B mesons, B+ to etac K+ and B+ to
J/psi K+, where the etac and J/psi subsequently decay into a p pbar or Lambda
Lambdabar pair. We measure the J/psi to p pbar, Lambda Lambdabar anisotropy
parameters, alpha_B = -0.60 +- 0.13 +-0.14 (p pbar), -0.44 +- 0.51 +- 0.31
(Lambda Lambdabar) and compare to results from e+e- to J/psi formation
experiments. We also report the first observation of etac to Lambda Lambdabar.
The measured branching fraction is B(etac to Lambda Lambdabar) = (0.87 +0.24
-0.21(stat) +0.09 -0.14(syst) +- 0.27 (PDG)) x 10^-3. This study is based on a
357 fb^-1 data sample recorded on the Upsilon(4S) resonance with the Belle
detector at the KEKB asymmetric-energy e+e- collider.Comment: 8 pages, two figures (4 figure files), an update of hep-ex/0509020
for journal submissio
Time-dependent CP Asymmetries in Decays
We report the first measurement of CP-violation parameters in B^0 ->
K_S^0\rho^0\gamma decays based on 657 million B\bar B pairs collected with the
Belle detector at the KEKB asymmetric-energy collider. We measure the
time-dependent CP violating parameter S_{K_S^0\rho^0\gamma}= 0.11 +/-
0.33(stat.)^{+0.05}_{-0.09}(syst.). We also obtain the effective direct CP
violating parameter A_eff=0.05 +/- 0.18(stat.) +/- 0.06(syst.) for
m_{K_S\pi^+\pi^-}<1.8 GeV/c^2 and 0.6 GeV/c^2<m_{\pi^+\pi^-}<0.9 GeV/c^2.Comment: 6 pages, 3 figures, to be submitted to PR
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