| 1. |
- Luo, J., et al.
(författare)
-
Transmit Beamforming for Inter-Operator Spectrum Sharing : From Theory to Practice
- 2012
-
Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - : IEEE conference proceedings. - 9781467307604 - 9781467307611 ; , s. 291-295
-
Konferensbidrag (refereegranskat)abstract
- In this paper, four transmit beamforming (BF) techniques are selected and compared to realize inter-operator spectrum sharing, which is a promising solution for the spectrum shortage problem. The BF techniques include two game-theoretic (GT) algorithms, zero-forcing (ZF) and minimum mean square error (MMSE). After a brief description of the BF techniques in a multiple-input single-output (MISO) system, their computational complexity is analyzed. The effectiveness of these techniques in real radio frequency (RF) signal transmission is verified by implementation on a flexible hardware-in-the-loop (HIL) testbed. First, several important aspects regarding practical implementation are discussed. Afterwards, the HIL measurement results are shown, where considerable sum rate gain can be observed due to spectrum sharing. Finally, the appropriate BF technique can be chosen based on a tradeoff between complexity and performance.
|
|
| 2. |
- Sarkar, N., et al.
(författare)
-
Effects of intramyocardial injection of phVEGF-A(165) as sole therapy in patients with refractory coronary artery disease - 12-month follow-up : Angiogenic gene therapy
- 2001
-
Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 250:5, s. 373-381
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. To test the safety and bioactivity of phVEGF-A(165) after intramyocardial injection during 12-month follow-up. Design. Open-labelled study. Subjects. Inclusion criteria were angina pectoris, Canadian Cardiovascular Society (CCS) class III-IV, unamenable to further revascularization, ejection fraction (EF) >30%, perfusion defects extending over >10% of the anterolateral left ventricle wall detectable with adenosine single photon emission computerized tomography (SPECT) and at least one patent vessel visible by coronary angiography. Seven of 39 patients referred for gene therapy were included. Intervention. Via a mini-thoracotomy under general anaesthesia, phVEGF-A(165) was injected directly into the myocardium at four sites in the anterolateral region of the left ventricle. Results. Operative procedures were uneventful. Perioperative release of myocardial markers and electrocardiogram (ECG) changes were detected in two patients. There were no perioperative deaths but one patient died 7 months postoperatively because of myocardial infarction. Plasma vascular endothelial growth factor (VEGF)-A levels increased two to threefold peaking 6 days postoperatively (P<0.004) and returning to baseline by day 30. A significant reduction in angina pectoris was reported. The CCS class improved from 3.30.2 to 1.9 +/-0.3 (P<0.01) and nitroglycerine intake decreased from 3915 to 12 +/-5 tablets week(-1) (P<0.001) 2 months after gene transfer. Improvements remained after 12 months when nitroglycerine consumption approached zero. Improved myocardial function in the phVEGF-A(165) injection region was documented in all patients (P<0.016) by tissue velocity imaging (TVI). Reduced reversible ischaemia was detected by adenosine SPECT in four patients. Improved collateralization was detected in four patients with coronary angiography. Conclusion. Intramyocardial injection of phVEGF-A(165) is safe and may lead to improved myocardial perfusion and function with longstanding symptomatic relief in end-stage angina pectoris. Based on these results this therapeutic potential is being tested in a double-blind placebo controlled multicentre trial, EUROINJECT ONE.
|
|
| 3. |
- Sylven, C., et al.
(författare)
-
Myocardial Doppler tissue velocity improves following myocardial gene therapy with VEGF-A(165) plasmid in patients with inoperable angina pectoris
- 2001
-
Ingår i: Coronary Artery Disease. - : Ovid Technologies (Wolters Kluwer Health). - 0954-6928 .- 1473-5830. ; 12:3, s. 239-243
-
Tidskriftsartikel (refereegranskat)abstract
- Background Myocardial tissue velocity and perfusion were studied in patients with severe angina pectoris following gene therapy by intramyocardial injection of phVEGF-A(165) via thoracotomy. Plasma concentrations of VEGF-A increased postoperatively. Two months after treatment anginal status and myocardial tissue velocity improved and perfusion showed a tendency to improve. Tissue velocity imaging appears to be a sensitive, objective method for detecting changes in myocardial function following gene therapy. Objective To study effects on myocardial tissue velocity and perfusion in patients with angina pectoris following intramyocardial injection of phVEGF-A(165) via thoracotomy. Design Open label, phase I/II. Methods Six patients with Canadian Cardiovascular Society (CCS) angina pectoris functional Glass III - IV and with major defects at adenosine stress single-photon emission computerized tomography (SPECT) were studied. In addition to SPECT, coronary angiography and dobutamine stress echocardiography with tissue Doppler velocity imaging were performed before and two months after gene transfer. Results Plasma concentrations of VEGF-A increased 2 to 3 times (P < 0.04) over baseline from 2 to 14 days after injection with normalization after 4 weeks. The CCS class improved about 40%, from 3.3 +/- 0.2 to 2.0 +/- 0.3 (P < 0.02) and nitroglycerine consumption decreased 30 - 40%, from 44 +/- 17 to 15 +/- 5 tablets per week (P < 0.05). The maximal systolic myocardial tissue velocity increased in all patients about 25% (P < 0.02) but did not reach the reference range. Myocardial perfusion at SPECT improved in four of the six patients. Conclusions Anginal status, myocardial tissue velocity and perfusion can be improved by phVEGF-A(165) intramyocardial injection. Tissue velocity imaging appears to be a sensitive, objective method for detecting changes in myocardial function following gene therapy. Coron Artery Dis 12:239-243
|
|
| 4. |
|
|
| 5. |
- Ehrenberg, J., et al.
(författare)
-
Retrograde crystalloid cardioplegia preserves left ventricular systolic function better than antegrade cardioplegia in patients with occluded coronary arteries
- 2000
-
Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier BV. - 1053-0770 .- 1532-8422. ; 14:4, s. 383-387
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate retrograde and antegrade crystalloid cardioplegia in terms of cardiac cooling and postoperative cardiac function. Design: Prospective, randomized, and blinded. Setting: University hospital. Participants: Twenty male patients with triple-vessel disease and proximal occlusion of the circumflex or the left anterior descending coronary artery. Interventions: Left ventricular ejection fraction at rest and during exercise was evaluated by nuclear ventriculography the day before and 3 months after surgery. After induction of anesthesia and hourly for the first 5 postoperative hours, hemodynamic. echocardiographic, and electrocardiographic data were acquired. Myocardial temperature was measured with needle thermistors in 3 myocardial regions. Measurements and Main Results: Demographic and temperature data were analyzed by t-test. Hemodynamic and echocardiographic data were analyzed by analysis of variance. The groups were similar in baseline characteristics. Retrograde cardioplegia cooled the region distal to an occlusion better than antegrade cardioplegia (9.6 degrees C +/- 4.8 degrees C v 21.8 degrees C +/- 5.9 degrees C; p < 0.01). Hemodynamic, echocardiographic, and electrocardiographic data did not differ between the groups. Three months after surgery, the retrograde cardioplegia group showed a higher left ventricular ejection fraction at rest (58% +/- 10% v 47% +/- 10%; p < 0.02) and during exercise (58% +/- 13% v 47% +/- 10%; p < 0.05) compared with the antegrade cardioplegia group. Conclusions: Retrograde cardioplegia provides more homogenous myocardial cooling than antegrade cardioplegia in hearts with coronary artery occlusions. The use of retrograde cardioplegia seems to benefit long-term left ventricular function.
|
|
| 6. |
|
|
| 7. |
- Sundberg, Johan, et al.
(författare)
-
Voice source, formant frequencies and vocal tract shape in overtone singing. A case study
- 2021
-
Ingår i: Logopedics, Phoniatrics, Vocology. - : Informa UK Limited. - 1401-5439 .- 1651-2022. ; , s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: In overtone singing a singer produces two pitches simultaneously, a low-pitched, continuous drone plus a melody played on the higher, flutelike and strongly enhanced overtones of the drone. The purpose of this study was to analyse underlying acoustical, phonatory and articulatory phenomena. Methods: The voice source was analyzed by inverse filtering the sound, the articulation from a dynamic MRI video of the vocal tract profile, and the lip opening from a frontal-view video recording. Vocal tract cross-distances were measured in the MR recording and converted to area functions, the formant frequencies of which computed. Results: Inverse filtering revealed that the overtone enhancement resulted from a close clustering of formants 2 and 3. The MRI material showed that for low enhanced overtone frequencies (F E) the tongue tip was raised and strongly retracted, while for high F E the tongue tip was less retracted but forming a longer constriction. Thus, the tongue configuration changed from an apical/anterior to a dorsal/posterior articulation. The formant frequencies derived from the area functions matched almost perfectly those used for the inverse filtering. Further, analyses of the area functions revealed that the second formant frequency was strongly dependent on the back cavity, and the third on the front cavity, which acted like a Helmholtz resonator, tuned by the tongue tip position and lip opening. Conclusions: This type of overtone singing can be fully explained by the well-established source-filter theory of voice production, as recently found by Bergevin et al. [1] for another type of overtone singing.
|
|
| 8. |
- Takman, Per, et al.
(författare)
-
High-resolution compact x-ray microscopy
- 2007
-
Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 226:2, s. 175-181
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate compact full-field soft X-ray transmission microscopy with sub 60-nm resolution operating at λ= 2.48 nm. The microscope is based on a 100-Hz regenerative liquid-nitrogen-jet laser-plasma source in combination with a condenser zone plate and a micro-zone plate objective for high-resolution imaging onto a 2048 × 2048 pixel CCD detector. The sample holder is mounted in a helium atmosphere and allows imaging of both dry and wet specimens. The microscope design enables fast sample switching and the sample can be pre-aligned using a visible-light microscope. High-quality images can be acquired with exposure times of less than 5 min. We demonstrate the performance of the microscope using both dry and wet samples.
|
|
| 9. |
- van Schijndel, N. H., et al.
(författare)
-
Adaptive RD Optimized Hybrid Sound Coding
- 2008
-
Ingår i: Journal of The Audio Engineering Society. - 1549-4950. ; 56:10, s. 787-809
-
Tidskriftsartikel (refereegranskat)abstract
- Traditionally, sound codecs have been developed with a particular application in mind, their performance being optimized for specific types of input signals, such as speech or audio (music), and application constraints, such as low bit rate, high quality, or low delay. There is, however, an increasing need for more generic sound codecs, created by the emergence of heterogeneous networks and the convergence of communication and entertainment devices. To obtain such versatility, this study employs hybrid sound coding based on operational rate-distortion (RD) optimization principles. Applying this concept, a prototype coder has been implemented with emphasis on (dynamic) adaptation to the input and to application constraints. With this prototype, listening tests have been performed for different application scenarios. The results demonstrate the versatility of the concept while keeping competitive sound quality compared to dedicated state-of-the-art codecs.
|
|
| 10. |
- Vogt, Ulrich, et al.
(författare)
-
Towards Soft X-Ray Phase-Sensitive Imaging with Diffractive Optical Elements
- 2006
-
Ingår i: Proc. 8th International Conference X-ray Microscopy. ; , s. 91-93
-
Konferensbidrag (refereegranskat)abstract
- In this contribution we present the first diffractive optical elements for soft x-ray differential interference contrast microscopy.Due to an improved calculation method the nanofabrication accuracy of these optics is the same as for comparable normal zoneplate optics with the same outermost zone width. Different diffractive optical elements were fabricated with outermost zone widthof 100 nm, different spot separation directions and different phase relations between the two spots. The optics were successfullyused in experiments both at the synchrotron radiation based TWINMIC microscope and at the Stockholm compact liquid-nitrogenlaser-plasma source based microscope.
|
|
