The effect of gadolinium on the estimation of myelin has not been reported. The aim of the current study was to investigate the effects of gadolinium on automatic myelin and brain tissue volumetry ...via quantitative synthetic MR imaging.
The study included 36 patients who were referred for brain metastases screening, and quantitative synthetic MR imaging data before and after gadolinium-based contrast agent administration were analyzed retrospectively. Brain metastases were detected in 17 patients. WM volume, GM volume, CSF volume, non-WM/GM/CSF volume, myelin volume, brain parenchymal volume, myelin fraction (myelin volume/brain parenchymal volume), and intracranial volume were estimated. T1 and T2 relaxation times, proton density, and myelin partial volume per voxel averaged across the brain parenchyma were also analyzed.
In patients with and without metastases after gadolinium-based contrast agent administration, measurements of WM and myelin volumes, and myelin fraction were significantly increased (+26.65 and +29.42 mL, +10.14 and +12.46 mL, +0.88% and +1.09%, respectively), whereas measurements of GM, CSF, brain parenchymal, and intracranial volumes were significantly decreased (-36.23 and -34.49 mL, -20.77 and -18.94 mL, -6.76 and -2.84 mL, -27.41 and -21.84 mL, respectively). Non-WM/GM/CSF volume did not show a significant change. T1, T2, and proton density were significantly decreased (-51.34 and -46.84 ms, -2.67 and -4.70 ms, -1.05%, and -1.28%, respectively) after gadolinium-based contrast agent administration, whereas measurements of myelin partial volume were significantly increased (+0.78% and +0.75%, respectively).
Gadolinium had a significant effect on the automatic calculation of myelin and brain tissue volumes using quantitative synthetic MR imaging, which can be explained by decreases in T1, T2, and proton density.
We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay μ(+)e(+)γ. The ...likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the μ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.
Molecularly functionalizations of electrodes, including semiconductors, open new function and application. Especially in cases of a molecular electronic materials with molecular-catalyst and ...electrochemical reaction, functional connection between molecule and electrode is a key part of whole process to provide device function. In the case of such the man-made molecular-catalytic electrochemical reaction systems, there are two interfaces on an electrode; a solution phase-enzyme layer interface and an enzyme layer-electrode interface. These interfaces act as a chemical reaction (including enzymatic reaction) interface and a physicochemical reaction interface respectively. There are late-limits in both interfaces. The interfacial rate limits become conspicuous in cases of macro-molecular interface, as such as enzyme. In order to break down the interfacial rate-limits, the molecular interfaces have to be designed as optimized both physical structure and chemical structure. In the present manuscript describes the fabrication of macro-molecular interfaces on an electrode mainly based on authors resent research.
We studied the radiative muon decay
μ
+
→
e
+
ν
ν
¯
γ
by using for the first time an almost fully polarized muon source. We identified a large sample (
∼
13,000) of these decays in a total sample of
...1.8
×
10
14
positive muon decays collected in the MEG experiment in the years 2009–2010 and measured the branching ratio
B
(
μ
→
e
ν
ν
¯
γ
)
=
(
6.03
±
0.14
(
stat
.
)
±
0.53
(
sys
.
)
)
×
10
-
8
for
E
e
>
45
MeV
and
E
γ
>
40
MeV
, consistent with the Standard Model prediction. The precise measurement of this decay mode provides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for
μ
+
→
e
+
γ
process.
The MEG experiment makes use of one of the world's most intense low energy muon beams, in order to search for the lepton flavour violating process Formula omitted. We determined the residual beam ...polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be Formula omitted by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be Formula omitted at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our Formula omitted search induced by the muon radiative decay: Formula omitted.
Status of the Belle silicon vertex detector Natkaniec, Z.; Aihara, H.; Asano, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Volume:
560, Issue:
1
Journal Article
Peer reviewed
The old silicon vertex detector (SVD1) of the Belle detector, operating at the high-luminosity asymmetric energy e+e− collider KEKB, was replaced by an upgraded version (SVD2) in 2003. The new ...detector has modified geometry and redesigned readout electronics, providing a larger polar angle acceptance, better vertex resolution, improved radiation hardness and reduced dead time. The operation of the detector started successfully in October 2003. The basic concepts of the SVD2 design as well as its performance after 10 months of data taking are described in this paper.
Early pancreatic cancer is small and limited to the pancreas. In contrast, small pancreatic cancer may include peripancreatic vasculature or metastasis involvement. This study evaluates images of ...early pancreatic cancer on multidetector CT (MDCT) using contrast-enhanced multiphasic imaging, and post-processed pancreatic duct images. CT findings and pathological features were analysed in eight patients with early pancreatic cancer. Pathological evaluation included location, size and histological grading of the tumour. MDCT evaluation covered the maximum diameter of the main pancreatic duct (MPD), stenosis or obstruction of the MPD, loss of normal lobar texture and associated pancreatitis. Attenuation differences between normal pancreatic parenchyma and the tumour (AD-PT) were also measured. Focal stenosis or obstruction of the MPD with dilatation of the distal MPD was demonstrated in all patients. Associated pancreatitis occurred in six patients with tumours measuring 12 mm or greater. Loss of normal lobar texture was recognised in four cases with the tumour measuring 14 mm or greater. Statistically, low-attenuated lesions and high-attenuated lesions differed with respect to the tumour size (p<0.01), and a positive relationship was demonstrated between the tumour size and AD-PT (r = 0.84). In seven cases, AD-PT is higher during the arterial phase than the pancreatic phase. Early pancreatic cancer appears as low attenuation on early phase, and as high- to iso-attenuation during the pancreatic and delayed phases in respect to the tumour size. Focal stenosis or obstruction of the MPD with dilatation of the distal MPD observed on curved reformation imaging seems important in the diagnosis of early pancreatic cancer.
We have developed a new germanium (Ge) detector unit for hypernuclear γ-ray spectroscopy at J-PARC, which comprises a new Ge detector array Hyperball-J. A compact pulse-tube refrigerator is coupled ...to a coaxial Ge detector in order to achieve lower crystal temperatures as a means to increase radiation hardness. The obtained crystal temperature is 72K, while an energy resolution is maintained at (FWHM) 3.1(1)keV for 1.33MeV γ rays using a gate-integrated shaping amplifier (ORTEC 973U). Gain shifts with changing crystal temperature are also confirmed for the Ge detector.
The MEG experiment makes use of one of the world’s most intense low energy muon beams, in order to search for the lepton flavour violating process
μ
+
→
e
+
γ
. We determined the residual beam ...polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be
P
μ
=
-
1
by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be
P
μ
=
-
0.86
±
0.02
(
stat
)
-
0.06
+
0.05
(
syst
)
at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our
μ
+
→
e
+
γ
search induced by the muon radiative decay:
μ
+
→
e
+
ν
¯
μ
ν
e
γ
.
The MEG experiment at PSI searches for the decay
μ
→
e
γ
at a level of
≈
10
−
13
on the branching ratio
BR
(
μ
→
e
γ
/
μ
→
tot
), well beyond the present experimental limit (
BR
≤
1.2
×
10
−
11
) and ...is sensitive to the predictions of SUSY-GUT theories. To reach this goal the experiment uses one of the most intense continuous surface muon beams available (
≈
10
8
μ
/
s
) and relies on advanced technology (LXe calorimetry, a gradient-field superconducting spectrometer as well as flexible and powerful trigger and acquisition systems). In order to maintain the highest possible energy, time and spatial resolutions for such detector, frequent calibration and monitoring, using a Cockcroft–Walton proton accelerator, are required. The proton beam is brought to the centre of MEG by a special bellows insertion system and travels in a direction opposite to the one of the normal
μ
‐
beam
. Protons interact with a lithium tetraborate (Li
2B
4O
7) nuclear target and produce one
γ
(17.6
MeV) from the reaction
Li
(
p
,
γ
)
3
7
Be
4
8
or two coincident
γ
s
(11.67 and 4.4
MeV) from the reaction
B
(
p
,
γ
1
)
5
11
C
⁎
6
12
. The 17.6
MeV
γ
is used for calibrating and monitoring the LXe calorimeter (
σ
E
γ
/
E
γ
=
3.85
±
0.15
%
at 17.6
MeV) while the coincident 11.67 and 4.4
MeV
γ
s
are used to measure the relative timing of the calorimeter and the spectrometer timing counters (
σ
Δ
t
=
0.450
±
0.015
ns
).
►Experiments that search for rare phenomena need to be constantly monitor and calibrated. ►We show that proton induced nuclear reactions generate
γ
‐
rays
useful for calibrating and monitoring the MEG experiment. ►We describe the design, assembly and test of the calibration and monitoring accelerator for the MEG experiment.
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