| 1. |
- De Koning, H. J., et al.
(författare)
-
Large-scale randomized prostate cancer screening trials : Program performances in the european randomized screening for prostate cancer trial and the prostate, lung, colorectal and ovary cancer trial
- 2002
-
Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136. ; 97:2, s. 237-244
-
Tidskriftsartikel (refereegranskat)abstract
- Two large-scale randomized screening trials, the Prostate, Lung, Colorectal and Ovary (PLCO) cancer trial in the USA and the European Randomized Screening for Prostate Cancer (ERSPC) trial in Europe are currently under way, aimed at assessing whether screening reduces prostate cancer mortality. Up to the end of 1998, 102,691 men have been randomized to the intervention arm and 115,322 to the control arm (which represents 83% of the target sample size) from 7 European countries and 10 screening centers in the USA. The principal screening method at all centers is determination of serum prostate-specific antigen (PSA). The PLCO trial and some European centers use also digital rectal examination (DRE) as an ancillary screening test. In the core age group (55-69 years), 3,362 of 32,486 men screened (10%) had a serum PSA concentration of 4 ng/ml or greater, which is I cut-off for biopsy (performed in 84%). An additional 6% was referred for further assessment based on other criteria, with much less efficiency. Differences in PSA by country are largely attributable to the age structure of the study population. The mean age-specific PSA levels are lower in the PLCO trial (1.64 ng/ml [in the age group 55-59 years], 1.80 [60-64 years] and 2.18 [65-69 years) than in the ERSPC trial (1.28-1.71 [55-59], 1.75-2.87 [60-64] and 2.48-3.06 [65-69 years]). Detection rates at the first screen in the ERSPC trial range from II to 42/1,000 men screened and reflect underlying differences in incidence rates and screening procedures. In centers with consent to randomization design, adherence in the screening arm is 91%, but less than half of the men in the target population are enrolled in the trial. In population-based centers in which men were randomized prior to consent, all eligible subjects are enrolled, but only about two-thirds of the men in the intervention arm undergo screening. Considerable progress has been made in both trials. Enrollment will be completed in 2001. A substantial number of early prostate cancers have been detected. The differences between countries seem to reflect both underlying prostate cancer incidence and screening policy. The trials have the power to show definitive results in 2005-2008.
|
|
| 2. |
|
|
| 3. |
- Berndsen, Fritz H
(författare)
-
The changing path of inguinal hernia surgery
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inguinal hernia repair is the most common operation in general surgery and the main challenge has been to lower the recurrence rate. With the introduction of endoscopic repair in the beginning of the 1990´s, the demand for randomised controlled studies has increased resulting in a growing interest in this surgical field. Standardised techniques with a growing use of tension free mesh repairs, teaching programs and registers are in a continuous developing process. After introduction of these changes at the County Hospital of Karlskrona a tenfold decrease in recurrence rate was accomplished at five years follow up (28% to 3%). The SMIL-group (Swedish Multicenter trial of Inguinal hernia repair by Laparoscopy) was formed in 1993 to conduct large randomised multicenter studies comparing laparoscopic and standardised open repairs. The SMIL-1 study comparing laparoscopic (TAPP) and Shouldice operation showed no difference in complication rate but patients in the TAPP group had less postoperative pain, better postoperative functional status and shorter sick leave at the price of a longer operation time. The recurrence rate at five years follow up was 6.6% in the TAPP group and 6.7% in the Shouldice group (ns). There was a correlation between poor surgical performance and recurrence rate. Inguinal hernia patients show bilateral disease at admission in 15%-20%. In the past, two consecutive operations have been performed. Simultaneous endoscopic operation in 168 patients (336 hernias) was safe with few major complications, a three years recurrence rate of 2.7% and only one patient with severe late discomfort. It is known that mesh causes a foreign body reaction and the last decade new meshes has been introduced to minimise this effect. Theoretically, foreign body reaction could be a threat to the spermatic cord structures but this effect is poorly documented. In a rat model, comparing suture repair, standard polypropylene mesh and low weight composite polyglactin/polypropylene mesh, there was patency in all vas deferens. An impaired s-testosterone production and a reduced cross sectional area of the vas deferens was found in the composite mesh group. There was no difference in inflammation or fibrosis between the two mesh groups. This thesis has contributed in changing the path of inguinal hernia surgery by focusing on the introduction of standardised open and laparoscopic techniques and dealing further with potential problems associated with mesh implantation.
|
|
| 4. |
|
|
| 5. |
- Fukagata, K., et al.
(författare)
-
Anomalous velocity fluctuations in particulate turbulent channel flow
- 2001
-
Ingår i: International Journal of Multiphase Flow. - 0301-9322 .- 1879-3533. ; 27:4, s. 701-719
-
Tidskriftsartikel (refereegranskat)abstract
- Gas-particle turbulent channel flow at Re-tau = 644, loaded with copper particles at a mass flow ratio of 2%, is studied numerically by large eddy simulation (LES) coupled with Lagrangian particle tracking (LPT), Inter-particle collisions and correction of drag force in the vicinity of walls are accounted for. Focus is made on the influence of particle wall boundary conditions and their influence on the statistical structure of the flow, It is shown that accordance with experimental data can be improved if a mechanism which can suppress the direct re-entrainment of particles after the impact at the wall is present. Present result shows that inter-particle collisions may play an important role in the re-distribution of particle momentum among different components even at low mass loading conditions,
|
|
| 6. |
- Fukagata, K., et al.
(författare)
-
Dynamics of Brownian particles in a turbulent channel flow
- 2004
-
Ingår i: Heat and Mass Transfer. - : Springer Science and Business Media LLC. - 0947-7411 .- 1432-1181. ; 40:9, s. 715-726
-
Tidskriftsartikel (refereegranskat)abstract
- Turbulent channel flows with suspended particles are investigated by means of numerical simulations. The fluid velocity is computed by large eddy simulation. Motion of small graphite particles with diameter of 0.01-10 mum, corresponding to the Schmidt number, Sc, of 2.87 x 10(2)-6.22 x 10(6) and the particle relaxation time in wall unit, tau(p)(+), of 9.79 x 10(-5)-4.51, is computed by Lagrangian particle tracking. Relation between the particle relaxation time and the computed deposition velocity is found to be in good agreement with an empirical relation. The statistics of the particle motion in the vicinity of the wall are studied. Clear differences are found in dynamical behavior of particles with different sizes. Medium size particles show a strong dependence on the structure of the fluid flow, while small and large particles are considerably less sensitive.
|
|
| 7. |
- Gurniki, F., et al.
(författare)
-
LES of turbulent channel flow of a binary electrolyte
- 2000
-
Ingår i: Journal of Applied Electrochemistry. - 0021-891X .- 1572-8838. ; 30:12, s. 1335-1343
-
Tidskriftsartikel (refereegranskat)abstract
- The turbulent diffusion boundary layer in a binary electrolyte was considered at Schmidt numbers of 1, 10 and 100 and exchange current densities between 10(-4) A m(-2) and 10(-2) A m(-2). A numerical scheme was developed for efficient investigation of the dynamics by means of large eddy simulations. The methodology was examined by detailed comparisons with documented data from earlier large eddy and direct numerical simulations and good agreement was found. Application of the methodology to electrochemical mass transfer indicated that the exchange current density seems to have negligible effect on the mean concentration profile but it influences the structure of the fluctuating field in a visible manner.
|
|
| 8. |
- Ipek, Nulifer, et al.
(författare)
-
Simple analytical model predicting some features of the electrolytic steel-pickling process
- 2002
-
Ingår i: Russian journal of electrochemistry. - 1023-1935 .- 1608-3342. ; 38:3, s. 238-246
-
Tidskriftsartikel (refereegranskat)abstract
- Electrolytic pickling of steel with neutral solutions, to remove the surface scale, reduces the need for the use of strong acids as needed in conventional pickling. This study is a step towards a more in-depth understanding of the factors affecting the former process. A theoretical model, sufficiently simplified to allow analytical solution, is developed and evaluated to provide a first approximation of the potential and current distributions in the electrolyte and steel band. To gain knowledge and validate the model, a small electrolytic pickling cell is constructed, and experiments, including bubble generation and motion observation, are conducted. The experimental work has shown the remarkable bubble production and adherence to the surfaces, and its effects on reducing pickling efficiency and uniformity. The pickling efficiency is about 30%, confirming other researchers' results. The analytical model shows trends very similar to those observed in the experiments, and provides very valuable guidance. It shows, for example, that the current efficiency decreases as the electrode-band distance increases, and it increases with the band thickness and the band-to-electrolyte conductivity ratio, The energy efficiency decreases by orders of magnitude faster than the current efficiency with all of the above-mentioned parameters, because of the correspondingly strong drop in the band-surface potential. A large amount of current is lost due to interelectrode short circuiting.
|
|
| 9. |
- Olivas, P., et al.
(författare)
-
Electromagnetic control of electroplating of a cylinder in forced convection
- 2004
-
Ingår i: Journal of Applied Electrochemistry. - 0021-891X .- 1572-8838. ; 34:1, s. 19-30
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous electrodeposition on a cylindrical cathode, e. g. electrodeposition of gold on electrical connectors, is usually characterized by an undesirable non- homogeneity of the deposit thickness. This has been observed in industrial applications. Numerical simulations have shown very good agreement with observations. This paper deals with the possibility of improving the homogeneity of the deposit thickness by a magnetic field that is parallel to the axis of the cylinder. The electromagnetic volume force generated by such a magnetic field may set up a swirling motion around the cylinder. By controlling the force density it is possible to control the thickness of the diffusive layer and consequently the mass transfer. The magnetic field can be optimized with respect to strength, spatial extent and variation with time. It is shown that a strong alternating magnetic field of low frequency gives a nearly homogeneous deposit.
|
|
| 10. |
- Widlund, O., et al.
(författare)
-
Structure information in rapid distortion analysis and one-point modeling of axisymmetric magnetohydrodynamic turbulence
- 2000
-
Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 12:10, s. 2609-2620
-
Tidskriftsartikel (refereegranskat)abstract
- It has recently been suggested that dimensionality information, as carried by the Reynolds dimensionality tensor, should be included in an extended Reynolds stress closure for modeling of magnetohydrodynamic (MHD) turbulence at low magnetic Reynolds numbers. This would enable more accurate modeling of the Joule dissipation, and capture the length-scale anisotropies and tendencies towards two-dimensionality characteristic of MHD turbulence. In the present work, an evolution equation for the Reynolds dimensionality tensor is derived, based on the spectral formulation of the Navier-Stokes equations. Most of the terms in the equation require modeling. Rapid distortion theory (RDT) is applied to study the behavior of the different magnetic terms of the dimensionality and Reynolds stress tensor equations; a variety of different anisotropy states could be examined by letting magnetic forcing act on a number of initial spectral energy distributions obtained from axisymmetric strain. The properties and limitations of linear or bilinear invariant tensor models for the magnetic terms are evaluated. In the limit of large interaction numbers (where Joule dissipation dominates), the resulting model equations for the energy decay have analytic solutions. By choosing one model constant appropriately, these are made consistent with the asymptotic energy decay K similar to t(-1/2) predicted earlier by Moffatt. The long-term objective of these efforts is the development of an effective second-moment closure for engineering applications.
|
|
