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H. T. Wong,
H. B. Li,
S. T. Lin,
F. S. Lee,
V. Singh,
S. C. Wu, C. Y. Chang,
H. M. Chang,
C. P. Chen,
M. H. Chou, [......],
S. K. Lin,
J. Q. Lu,
H. Y. Sheng,
R. F. Su,
W. S. Tong,
B. Xin,
T. R. Yeh,
Q. Yue,
Z. Y. Zhou,
B. A. Zhuang
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[show abstract]
[hide abstract]
ABSTRACT: In acute ischemic stroke, the ability to estimate the penumbra and infarction core ratio helps to triage those who will potentially benefit from thrombolytic therapies. Flat-panel post-contrast DynaCT imaging can provide both vasculature and parenchymal blood volume within the angio room to monitor hemodynamic changes during the endovascular procedures. We report on an 80-year-old woman who suffered from an acute occlusion of the right distal cervical internal carotid artery. She was transferred to the angio room where in-room post-contrast flat-panel DynaCT imaging (syngo Neuro PBV IR) was performed to access the ischemic tissue, followed by successful mechanical thrombolytic therapy.
Interventional Neuroradiology 12/2012; 18(4):463-468. · 0.56 Impact Factor
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The OPAL Collaboration,
G. Abbiendi,
C. Ainsley,
P. F. Åkesson,
G. Alexander,
G. Anagnostou,
K. J. Anderson,
S. Asai,
D. Axen,
I. Bailey, [......],
P. S. Wells,
T. Wengler,
N. Wermes,
G. W. Wilson,
J. A. Wilson,
G. Wolf,
T. R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: Hadronic event shape distributions from e+e− annihilation measured by the OPAL experiment at centre-of-mass energies between 91GeV and 209GeV are used to determine
the strong coupling α
S. The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations
matched to the resummed next-to-leading-log-approximation terms (NNLO + NLLA). The combined NNLO result from all variables
and centre-of-mass energies is
while the combined NNLO + NLLA result is
The completeness of the NNLO and NNLO + NLLA results with respect to missing higher order contributions, studied by varying
the renormalization scale, is improved compared to previous results based on NLO or NLO + NLLA predictions only. The observed
energy dependence of α
S agrees with the QCD prediction of asymptotic freedom and excludes the absence of running.
European Physical Journal C 04/2012; 71(9):1-21. · 3.63 Impact Factor
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The OPAL Collaboration,
G. Abbiendi,
C. Ainsley,
P. F. Åkesson,
G. Alexander,
G. Anagnostou,
K. J. Anderson,
S. Asai,
D. Axen,
I. Bailey, [......],
T. Wengler,
N. Wermes,
D. Wetterling,
G. W. Wilson,
J. A. Wilson,
G. Wolf,
T. R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: Data collected around
Ös=91\sqrt{s}=91
GeV by the OPAL experiment at the LEP e+e− collider are used to study the mechanism of baryon formation. As the signature, the fraction of Σ− hyperons whose baryon number is compensated by the production of a
[`(S-)],[`(L)]\overline{\Sigma^{-}},\overline{\Lambda}
or
[`(X-)]\overline{\Xi^{-}}
antihyperon is determined. The method relies entirely on quantum number correlations of the baryons, and not rapidity correlations,
making it more model independent than previous studies. Within the context of the JETSET implementation of the string hadronization
model, the diquark baryon production model without the popcorn mechanism is strongly disfavored with a significance of 3.8
standard deviations including systematic uncertainties. It is shown that previous studies of the popcorn mechanism with
L[`(L)]\Lambda \overline{\Lambda}
and
p\uppi[`(p)]\mathrm{p}\uppi \overline{\mathrm{p}}
correlations are not conclusive, if parameter uncertainties are considered.
European Physical Journal C 04/2012; 64(4):609-625. · 3.63 Impact Factor
-
G. Abbiendi,
C. Ainsley,
P.F. Åkesson,
G. Alexander,
G. Anagnostou,
K.J. Anderson,
S. Asai,
D. Axen,
I. Bailey,
E. Barberio, [......],
T. Wengler,
N. Wermes,
G.W. Wilson,
J.A. Wilson,
G. Wolf,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
The OPAL Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A study of Bose–Einstein correlations in pairs of identically charged pions produced in e+e- annihilations at the Z0 peak has been performed for the first time assuming a non-static emitting source. The results are based on the high statistics
data obtained with the OPAL detector at LEP. The correlation functions have been analyzed in intervals of the average pair
transverse momentum and of the pair rapidity, in order to study possible correlations between the pion production points and
their momenta (position–momentum correlations). The Yano–Koonin and the Bertsch–Pratt parameterizations have been fitted to
the measured correlation functions to estimate the geometrical parameters of the source as well as the velocity of the source
elements with respect to the overall centre-of-mass frame. The source rapidity is found to scale approximately with the pair
rapidity, and both the longitudinal and transverse source dimensions are found to decrease for increasing average pair transverse
momenta.
European Physical Journal C 04/2012; 52(4):787-803. · 3.63 Impact Factor
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S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
G.W. Wilson,
J.A. Wilson,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
S. Heinemeyer,
A. Pilaftsis,
G. Weiglein,
The LEP Working Group for Higgs Boson Searches
[show abstract]
[hide abstract]
ABSTRACT: The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by
the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined
for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no
significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper
bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number
of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large
exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses
of neutral Higgs bosons.
European Physical Journal C 04/2012; 47(3):547-587. · 3.63 Impact Factor
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G. Abbiendi,
C. Ainsley,
P.F. Åkesson,
G. Alexander,
G. Anagnostou,
K.J. Anderson,
S. Asai,
D. Axen,
I. Bailey,
E. Barberio, [......],
T. Wengler,
N. Wermes,
G.W. Wilson,
J.A. Wilson,
G. Wolf,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
The OPAL Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass
of the Z boson with the OPAL detector at LEP. The strong coupling αs is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies
ranging from 24GeV to 78GeV, and the energy dependence of αs is studied. Our results are consistent with the running of αs as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z decays with hard and
isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different
event shape observables and energies gives αs(MZ)=0.1182±0.0015(stat.)±0.0101(syst.).
European Physical Journal C 04/2012; 53(1):21-39. · 3.63 Impact Factor
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G. Abbiendi,
C. Ainsley,
P.F. Åkesson,
G. Alexander,
G. Anagnostou,
K.J. Anderson,
S. Asai,
D. Axen,
I. Bailey,
E. Barberio, [......],
T. Wengler,
N. Wermes,
G.W. Wilson,
J.A. Wilson,
G. Wolf,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
The OPAL Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Data from e+e- annihilation into hadrons at centre-of-mass energies between 91GeV and 209GeV collected with the OPAL detector at LEP,
are used to study the four-jet rate as a function of the Durham algorithm resolution parameter ycut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The
strong coupling measured from the four-jet rate is
a\textS(M\textZ0)=0.1182±0.0003(\textstat.)±0.0015(\textexp.) ±0.0011(\texthad.)±0.0012(\textscale)±0.0013(\textmass),\alpha_{\text{S}(M_{\text{Z}^0})}=0.1182\pm0.0003(\text{stat.})\pm0.0015(\text{exp.}) \pm0.0011(\text{had.})\pm0.0012(\text{scale})\pm0.0013(\text{mass}),
in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables
are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties.
European Physical Journal C 04/2012; 47(2):295-307. · 3.63 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Intracranial hemodynamics are important for management of SOAD. This study aimed to monitor peri-stent placement intracranial CirT of patients with SOAD.
Twenty-five patients received stent placement for extracranial ICA stenosis, and 34 patients with normal CirT were recruited as controls. Their color-coded DSAs were used to define the Tmax of selected intravascular ROI. A total of 20 ROIs of the ICA, OphA, ACA, MCA, FV, PV, OV, SSS, SS, IJV, and MCV were selected. rTmax was defined as the Tmax at the selected region of interest minus Tmax at the cervical segment of the ICA (I1 on AP view and IA on lateral view). rTmax of the PV was defined as intracranial CirT. Intergroup and intragroup longitudinal comparisons of rTmax were performed.
rTmax values of the normal cohorts were as follows: ICA-AP, 0.12; ICA-LAT, 0.10; A1, 0.28; A2, 0.53; A3, 0.81; M1, 0.40; M2, 0.80; M3, 0.95; OphA, 0.35; FV, 4.83; PV, 5.11; OV, 5.17; SSS, 6.16; SS, 6.51; IJV, 6.81; and MCV, 3.86 seconds. Before stent placement, the rTmax values of arterial ROIs, except A3 and M3, were prolonged compared with values from control subjects (P < .05). None of the rTmax of any venous ROIs in the stenotic group was prolonged with significance. After stent placement, the rTmax of all arterial ROIs shortened significantly, except A1and M3. Poststenting rTmax was not different from the control group.
Without extra contrast medium and radiation dosages, color-coded quantitative DSA enables real-time monitoring of peri-therapeutic intracranial CirT in patients with SOAD .
American Journal of Neuroradiology 04/2012; 33(9):1685-90. · 2.93 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We report a 49-year-old right lobe liver transplant recipient, who developed a significant anastomotic stenosis of the right hepatic vein shortly thereafter. Shear wave elastography (SWE) was applied to investigate liver stiffness quantitatively. It showed increased stiffness in the anterior compared with the posterior segment of right lobe graft. The stenotic right hepatic venous anastomosis was then managed by angioplasty with stent placement. SWE after angioplasty showed a gradual decrease in stiffness of the anterior segment, which was almost equal to the posterior segment at 2 weeks thereafter. Our experience suggested that SWE may be a noninvasive tool to assess alterations in liver stiffness secondary to hepatic venous congestion after liver transplantation.
Transplantation Proceedings 04/2012; 44(3):814-6. · 1.00 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The mortality rate among patients with septic shock is high despite current therapy. We present a case of Fournier's gangrene and septic shock at 4 years post-heart transplantation that was reversed by "continuous enteral feeding" of the digestive enzyme inhibitor, gabexate mesilate. Recently, powerful pancreatic digestive proteases in the lumen of the intestine have been identified as initiators of the systemic inflammatory response. Intraluminal inhibitions of the proteases significantly attenuates intestinal damage, system inflammation, and multiorgan failure in experimental forms of shock but it has not been tested in man.
Gabexate mesilate, a synthetic digestive protease inhibitor, was continuously administered in two liters of crystalloid solution to a patient by enteral feeding during septic shock. The condition and markers for shock due to sepsis reversed in a few days.
This case suggested that "enteral" digestive protease inhibition may decrease and even reverse the sequelae of shock and sepsis.
Transplantation Proceedings 04/2012; 44(3):817-9. · 1.00 Impact Factor
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E. A. Douglas, C. Y. Chang,
B. P. Gila,
M. R. Holzworth,
K. S. Jones,
L. Liu,
Jinhyung Kim,
Soohwan Jang,
G. D. Via,
Fan Ren,
S. J. Pearton
Microelectronics Reliability. 01/2012; 52:23-28.
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[show abstract]
[hide abstract]
ABSTRACT: A trilevel resist system was employed to fabricate self-aligned, submicron emitter finger In <sub>0.52</sub> Al <sub>0.48</sub> As / In <sub>0.42</sub> Ga <sub>0.58</sub> As <sub>0.77</sub> Sb <sub>0.23</sub>/ In <sub>0.53</sub> Ga <sub>0.47</sub> As double heterojunction bipolar transistors (DHBTs). Selective wet-etchants were used to define the emitter fingers and to form an InGaAs guard-ring around the emitter fingers. Due to the low energy bandgap of the InGaAsSb base layer and type II base-collector junction, a low turn-on voltage of 0.38 V at 1 A / cm <sup>2</sup> and a high dc current gain of 123.8 for a DHBT with a 0.65×8.65 μ m <sup>2</sup> emitter area were obtained. A unity gain cutoff frequency (f<sub>T</sub>) of 260 GHz and a maximum oscillation frequency (f<sub> max </sub>) of 485 GHz at J<sub>C</sub>=302 kA / cm <sup>2</sup> were achieved.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 06/2011; · 1.34 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Ti/Al/Ni/Au Ohmic contact metallization on InAlN/GaN heterostructures both with and without a thin GaN cap layer was annealed at different temperatures. The minimum transfer resistance for the contacts of 0.65 Ω mm (specific contact resistivity of 2×10<sup>-5</sup> Ω cm <sup>2</sup> ) was achieved after 800 ° C annealing for structures without the GaN cap, while those with the cap exhibited their lowest resistance at higher temperatures. The contact morphology showed considerable roughening by 750 ° C but the carrier mobility was stable until annealing temperatures of 850 ° C . Diffuse scattering experiments showed that the morphological roughness of the InAlN/GaN interface increased as a result of annealing at these temperatures and the data were consistent with outdiffusion of Ga into the InAlN. Unpassivated high electron mobility transistors with a gate dimension of 0.7×180 μ m <sup>2</sup> were fabricated using these contacts and showed a maximum drain current of 1.3 A/mm and an extrinsic transconductance of 366 mS/mm. The presence of the GaN cap increased the effective barrier height of Ni/Au Schottky contacts from 0.91 to 1.01 eV on the heterostructure.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 04/2011; · 1.34 Impact Factor
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E. A. Douglas, C. Y. Chang,
D. J. Cheney,
B. P. Gila,
C. F. Lo,
Liu Lu,
M. R. Holzworth,
P. Whiting,
K. S. Jones,
G. D. Via,
Jinhyung Kim,
Soohwan Jang,
Fan Ren,
S. J. Pearton
Microelectronics Reliability. 01/2011; 51:207-211.
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[show abstract]
[hide abstract]
ABSTRACT: Nitrogen ion-implanted AlGaN/GaN high electron mobility transistor structures showed an isolation blocking voltage of 900 V with a leakage current at 1 μA/mm across an implanted isolation-gap of 10 μm between two Ohmic pads. The effect of implanted gap distance (1.7, 5, or 10 μm) between two Ohmic contact pads was evaluated. The isolation current density was determined to be solely dependent on the applied field between the contact pads. A model using a combination of resistive current and Poole–Frenkel current is consistent with the experimental data. The resistance of the isolation implantation region significantly decreased after the sample was annealed at temperatures above 600 °C.
Applied Physics Letters 12/2010; 97(26):262116-262116-3. · 3.84 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The morphology of ultrathin AlN/GaN high electron mobility transistors without or with TiAlNiAu Ohmic contacts, and annealed from 750 to 950 ° C , has been investigated using transmission electron microscopy and associated analytical techniques. After annealing, the contact surface roughness was degraded due to intermixing and phase separation of the metal layers. TiN contact inclusions (CIs) that had penetrated through the AlN layers into the underlying GaN layers along threading dislocations, were observed in all annealed samples. The CI density increased with increasing annealing temperature but the lowest specific contact resistivity was obtained for structures annealed at 850 ° C . Annealing at 950 ° C caused cracking on the contact metal surface. The AlN layers remained intact in dislocation-free areas of all samples. The relationship between annealing temperature, interfacial structure and contact resistance is also discussed.
Journal of Applied Physics 11/2010; · 2.17 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The properties of Ti/Al/Ni/Au Ohmic contacts on n-type a-plane GaN epitaxial layers directly grown on r-plane sapphire substrates are reported. The minimum specific contact resistance of ~10−5 Ω cm2 was achieved after annealing at 650–700 °C. Ohmic contact properties were measured using transmission line method patterns oriented in both the m- and c-axis directions of a-plane GaN. The sheet resistance of a-plane GaN along the c-axis was two times higher than that along the m-axis, which shows significant electric anisotropy in the two orientations.
Journal of Physics D Applied Physics 07/2010; 43(29):295102. · 2.54 Impact Factor
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B.H. Chu,
Y.L. Wang,
H.T. Wang, C.Y. Chang,
C.F. Lo,
S.J. Pearton,
G. Papadi,
J.K. Coleman,
B.J. Sheppard,
C.F. Dungen,
Kevin Kroll,
Nancy Denslow,
A. Dabiran,
P.P. Chow,
J.W. Johnson,
E.L. Pine,
K.J. Linthicum,
F. Ren
[show abstract]
[hide abstract]
ABSTRACT: A promising sensing technology utilizing AlGaN/GaN high electron mobility transistors (HEMTs) has been developed to analyze a wide variety of environmental and biological gases and liquids. The conducting 2DEG channel of GaN/AlGaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. Examples of detecting mercury ions, Perkinsus sp. protozoan pathogens of marine molluscs, lactic acid, and an endocrine disrupter biomarker (vitellogenin) are discussed in this paper. Detection limits of 10-7 M, 5 μg/ml and 167 nM for mercury ions, vitellogein and lactic acid, respectively, were achieved.
Nanoscience and Nanotechnology Letters 05/2010; 2(2):120-128. · 0.53 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Reliability studies of InAlAs/InGaAs metamorphic high electron mobility transistors (MHEMTs) grown on GaAs substrates for high frequency/power applications are reported. The MHEMTs were stressed at a drain voltage of 3 V for 36 h, as well as undergoing a thermal storage test at 250 ° C for 48 h. The drain current density of the MHEMTs at zero gate bias dropped about 12.5% after either the thermal storage experiment or dc stress. The gate current of the MHEMT devices with thermal storage was much higher than that of devices after dc stress. In the latter case, significant gate sinking was observed by transmission electron microscopy. The main degradation mechanism during thermal storage was the reaction of the Ohmic contact with the underlying semiconductor.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 04/2010; · 1.34 Impact Factor
