| 1. |
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| 2. |
- Kullenberg, Bertil, et al.
(författare)
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Entomology
- 1976
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Ingår i: Uppsala University 500 years. - Uppsala : Uppsala universitet. ; , s. 55-64
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Adiels, Lars, et al.
(författare)
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A π0 and η spectrometer of lead glass and BGO for momenta up to 1 GeV/c
- 1986
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 244:3, s. 380-390
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Tidskriftsartikel (refereegranskat)abstract
- A spectrometer consisting of two sets of bismuth germanium oxide (BGO) crystals and a lead-glass array has been used to measure the [pi]0 and [eta] momentum spectra produced from proton-antiproton annihilations at rest. We describe the test of the BGO sets in electron beams of energies from 50 to 450 MeV. We discuss the method of construction and calibration of the lead-glass array, as well as procedures to extract the energy and position resolutions for detected photons. A momentum resolution ([sigma]) for [pi]0’s and [eta]’s of 4% and 3%, respectively has been achieved at momenta below 1 GeV/c.
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| 4. |
- Adiels, Lars, et al.
(författare)
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Experimental study of the inclusive η-spectrum from proton-antiproton annihilations at rest in liquid hydrogen
- 1989
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Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739 .- 1431-5858. ; 42, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- The inclusive η-momentum spectrum from Mathematical expression annihilations at rest in liquid hydrogen was measured at LEAR. Branching ratios were obtained for Mathematical expression, and ηη(8.1±3.1)×10-5. An upper limit for Mathematical expression of 1.8×10-4 at 95% CL was found. The ratio of the branching ratios is BR(ηÏvariant)/BR(ηω)=0.51-0.06+0.20. For the ratio of branching ratios into two pseudoscalar mesons, we have BR(ηπ0)/BR(Ï€0Ï€0)=0.65±0.14, BR(ηη)/BR(Ï€0Ï€0), BR(ηη′)/BR(Ï€0Ï€0) at 95% CL, and BR(ηη)/BR(ηπ0). © 1989 Springer-Verlag.
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| 5. |
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| 6. |
- Adiels, Lars, 1952-, et al.
(författare)
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Test of CP violation with K0 and K‾0 at LEAR
- 1985
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Ingår i: Physics with antiprotons at LEAR in the ACOL era. - Gif sur Yvette : Editions Frontières. - 2863320351 ; , s. 467-482
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Antonsson, Ann-Beth, et al.
(författare)
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Möjligheter och begränsningar avseende användning av slutningsåtgärder för metallhaltiga vatten
- 1992
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Målsättningen för det här fleråriga projektet är att ta fram ett objektivt tekniskt/ekonomiskt underlag avseende olika separationsteknikers möjligheter och begränsningar att sluta en ytbehandlingsanläggning. Tyngdpunkten ligger på metallbeläggningssidan. I den första delen av projektet har vi på laboratoriet behandlat följande provvattentyper från ytbehandlare. - Sköljvatten från förkromning, förkoppring, förnickling och förzinkning - Totalavlopp efter konventionell fällning. Vi har behandlat vattnen med ett stort antal olika separationstekniker. Jonbyte, omvänd osmos, nanofiltrering, indunstning, elektrolys, elektrodialys, sulfidfällning, aktivt kol. Vad gäller avskiljningen av metall kan man konstatera att det går att producera ett vatten med mycket låga resthalter, framförallt med jonbyte, omvänd osmos och indunstning. Investeringskostnaden för dessa metoder ökar nu i nämnd ordning. Det finns många företag som använder separationstekniker i sina system (framför allt jonbyte). Emellertid används dessa oftast för att återanvända sköljvattnet. De metaller som uppkoncentreras fälls oftast ut som metallhydroxider. För att kunna återföra metaller och andra prestationskemikalier till processbadet krävs det att man uppnår rätt koncentration samtidigt som man inte ska återföra föroreningar till badet. Helst ska dessa blödas ut ur systemet. För de tekniker som studerats var avskiljningsförmågan för metall hög för alla metoder utom aktivt kol. För organiskt material var den hög för omvänd osmos och indunstning. För att kunna bedöma möjligheten att återföra koncentrat till baden krävs det kunskap om korrekt badsammansättning, tolerabla avvikelser samt innehåll i de koncentrat som ska återföras. I den här inledande delen av projektet kan vi konstatera att kunskapen kring dessa frågor många gånger är bristfällig. En genomgång av vilka kemikalier som kan finnas i sköljvattnen och vilka inneboende hälsorisker dessa besitter har sammanställts. Med utgångspunkt från detta har sedan tänkbara hälsorisker som kan uppstå vid slutning diskuterats. I etapp 2 kommer arbetsmiljöaspekterna att belysas ytterligare i samband med pilotkörningarna i fält. Jonbyte, omvänd osmos (RO) och indunstning kommer att utprovas under långvariga och realistiska omständigheter. Dessutom kommer Elektrodialys (ED) och elektrolys att utprovas på mer koncentrerade sparsköljar och koncentrat från de andra metoderna.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Bergström, Erik, 1944-
(författare)
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Cardiovascular risk indicators in adolescents : the Umeå youth study
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atherosclerotic cardiovascular diseases (CVD), particularly coronary heart disease (CHD) and cerebrovascular disease, are today major causes of death in the industrialised parts of the world. There are evidence to suggest that the atherosclerotic process starts in childhood, implying that preventive measures should be implemented already in children and adolescents.The aim of this study was to examine CVD risk indicators and their determinants in healthy Swedish adolescents. The study population comprised 14- and 17-year-old boys and girls (n=1032), in the dty and surroundings of Umeå in northern Sweden.Biochemical, anthropometric, and physiological parameters associated to CVD (s- lipoproteins and s-apolipoproteins, s-insulin, s-ferritin, anthropometric measurements, blood pressure, and physical fitness) were evaluated in relation to family history of CVD, weight and length at birth, infant feeding regimen, physical growth during infancy and childhood, current diet, physical activity, smoking, and educational level and occupation of the parents.The main findings of the study were that, on average, total serum cholesterol (TC) values in boys and girls were at the same level as reported from other European countries. A family history of CVD, short duration of breast feeding, low attained height during infancy and childhood, high body mass index (BMI), and low physical fitness were all associated with an unfavourable serum lipid profile. The findings also showed that features typical of the insulin resistance syndrome are present already in adolescents. In boys, iron stores, estimated by serum ferritin, were related to BMI and physical fitness, in a similar way as well established CVD risk indicators. Compared to previous dietary studies in Sweden, mean relative (energy %) fat intake had decreased substantially although the mean relative intake of saturated fat was still rather high. For both boys and girls, reported relative energy intake (energy intake/estimated energy expenditure) decreased with increasing level of BMI. Furthermore, daily smoking was more common among adolescents from families with low socio-economic status (SES) but was most strongly associated to smoking in peers. Tobacco use was considerably higher among adolescents attending vocational programs at secondary high school as compared to theoretical programs. Daily smokers had a more unfavourable serum lipid profile compared to non-smokers. Low socio-economic status of the parents was related to higher BMI and low educational level to higher dietary fat intake in both boys and girls.In conclusion, the findings of the study show that parameters linked to adult CVD when examined in adolescents, are related to family history, infant nutrition, previous physical growth, current body composition, physical fitness, physical activity, smoking, and social status and educational level of the parents.
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| 20. |
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| 21. |
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| 22. |
- Bergström, Lars, et al.
(författare)
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Backward production on nuclei and the tube model
- 1980
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Ingår i: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 21:1, s. 305-307
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the recent data from Burke et al. on backward production in 200-GeV/c nA collisions are in good agreement with expectations from the collective tube model with tube fragmentation taken into account.
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| 23. |
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| 24. |
- Bergström, Lars, et al.
(författare)
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Detection of High Energy Neutrinos in PAN
- 1992
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Ingår i: Proceedings of the Workshop on High Energy Neutrino Astrophysics, Univ. Hawaai at Manoa, Honolulu, Hawaii, March 23-26, 1992..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 25. |
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| 26. |
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| 27. |
- Bergström, Lars, et al.
(författare)
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Estimates of recoil nucleon spectra in high-energy hadron-nucleus collisions
- 1977
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 68:2, s. 177-179
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that recent data on the recoil nucleon spectrum in 10.5 GeV/c pion-neon collisions are in excellent agreement with a parameter free estimate from the so called tube model for high-energy hadron-nucleus collisions. A simple independent collision model is also treated.
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| 28. |
- Bergström, Lars
(författare)
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Evolution of laminar disturbances in pipe Poiseuille flow
- 1993
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Ingår i: European journal of mechanics. B, Fluids. - 0997-7546 .- 1873-7390. ; 12:6, s. 749-768
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Tidskriftsartikel (refereegranskat)abstract
- An experimental study on the evolution of localized disturbances in pipe Poiseuille flow has been performed. The aim was to investigate the relevance of the theoretical findings on the algebraic transient growth mechanism. For non-axisymmetric disturbances the amplitudes and the propagation velocities were measured in the laminar regime. The initial disturbances were induced radially through the pipe wall and had a distribution in the azimuthal direction corresponding to a periodicity of one and five, respectively. The amplitude of the resulting streamwise velocity perturbation was measured at different radial and axial positions by means of laser doppler velocimetry. In the laminar regime, the results showed that the disturbance peaks are actually amplified but will eventually decay as predicted in the theory. The peak of an initial disturbance of periodicity five showed a rapid amplification to a maximum before the decay sets in. The initial disturbance of periodicity gave a more slowly varying disturbance peak level over the investigated interval. The propagation speed of the front of the disturbances was in the range of 0.86-0.9 times the centreline velocity. The propagation speed of the disturbance peaks was in the range of 0.51 to 0.80 times the centreline velocity and dependent on the azimuthal distribution of the initial disturbance.
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| 29. |
- Bergström, Lars
(författare)
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Initial algebraic growth of small angular dependent disturbances in pipe Poiseuille flow
- 1992
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Ingår i: Studies in applied mathematics (Cambridge). - : Wiley. - 0022-2526 .- 1467-9590. ; 87:1, s. 61-79
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of small, angular dependent velocity disturbances in laminar pipe flow is studied. In particular, streamwise independent perturbations are considered. To fully describe the flow field, two equations are required, one for the radial and the other for the streamwise velocity perturbation. Whereas the former is homogeneous, the latter has the radial velocity component as a forcing term. The normal modes of the system are determined and analytical solutions for eigenfunctions, damping rates and phase velocities are calculated. Then, the initial value problem is treated and the time development of the disturbances is determined.
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| 30. |
- Bergström, Lars
(författare)
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Interactions of three components and subcritical self-sustained amplification of disturbances in plane Poiseuille flow
- 1999
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 11:3, s. 590-601
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Tidskriftsartikel (refereegranskat)abstract
- A low-dimensional nonlinear model for the normal velocity (v) and normal vorticity (eta) disturbance development in plane Poiseuille flow is studied. The study is restricted to the interactions of a pair of oblique components of the form e(/(alpha x+/-beta z)) and the component of the form e(/2 beta z) where alpha and beta are streamwise and spanwise wave numbers, respectively. The disturbances considered are also assumed to be highly elongated in the streamwise direction. Owing to the non-normal properties of the basic equations, the eta disturbance is first transiently amplified. Then, if the Reynolds number (R) and the initial disturbance are sufficiently large, the nonlinear interactions lead to a self-sustained process of disturbance amplification at subcritical R. For large R (R greater than or similar to 5000). the threshold disturbance amplitude scales like R-3. The, results also strongly indicate that the nonlinear feedback from eta to v is crucial for the establishment of the self-sustained process.
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| 31. |
- Bergström, Lars, et al.
(författare)
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Is the recently published counterproof of the tube model credible?
- 1978
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 78:2-3, s. 337-341
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that recent data from pion and proton collision with emulsion nuclei at 200 GeV/c are in perfect agreement with expectations from the collective tube model. The opposite conclusion in publications by Azimov et al. came about because the authors ignored the important effects of target fragmentation.
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| 32. |
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| 33. |
- Bergström, Lars
(författare)
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Nonlinear behaviour of transiently amplified disturbances in pipe Poiseuille flow
- 1995
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Ingår i: European journal of mechanics. B, Fluids. - 0997-7546 .- 1873-7390. ; 14:6, s. 719-735
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Tidskriftsartikel (refereegranskat)abstract
- The present work is a continuation of previous investigations of the author and deals with the nonlinear behaviour of transiently amplified disturbances in pipe Poiseuille flow. The disturbances are expanded in terms of a small amplitude parameter, and a spectral formulation, based on the eigenfunctions of the linear problem, is used to solve the resulting evolution equations. For the corresponding linear problem, analytical solutions are known. Here the author shows that the nonlinear problem also allows an analytical treatment. The analysis concentrates on the interaction of the dominating azimuthal wave number components of axially independent disturbances, since they exhibit largest growth in linear theory. The analysis is restricted to the first modes of the components, since these are found to dominate the disturbance magnitude at the peak amplification. In particular, the nonlinear correction for the component with an azimuthal wave number equal to one is considered. Including the nonlinear correction, the author reduces the linearly obtained amplification of the streamwise disturbance energy density and finds that the peak position of the disturbance energy density occurs earlier than for linear disturbance. This result is consistent with the experimental findings on transient growth for subcritical disturbances. Moreover, the reduced amplification is in agreement with recent results from direct numerical simulations of axially dependent disturbances.
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| 34. |
- Bergström, Lars
(författare)
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Optimal growth of small disturbances in pipe Poiseuille flow
- 1993
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Ingår i: Physics of Fluids. A, Fluid Dynamics (1989-1993). - : AIP Publishing. - 0899-8213. ; 5:11, s. 2710-2720
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical study is made of initial algebraic growth for small angular-dependent disturbances in pipe Poiseuille flow. The analysis is based on the homogeneous equation for the pressure for which the eigenvalue problem is solved numerically. In the limit of small streamwise wave numbers asymptotic results for the eigenvalues are derived. On the basis of the modes of the system, which are all damped, the initial value problem is considered and in particular the largest possible growth of the disturbance energy density is determined following the ideas of Butler and Farrell [Phys. Fluids A 4, 1637 (1992)]. The results show that a large amplification of the disturbance energy is possible. The largest amplification is obtained for disturbances with a small streamwise wave number and with an azimuthal wave number of one. The energy growth is then only due to the growth of the streamwise disturbance component. However, for disturbances of shorter wavelength, the energy growth is also substantial and not only concentrated to the streamwise velocity component. The wall shear corresponding to disturbances with the largest energy growth also shows a large amplification and the dependence of wave numbers and the Reynolds number is the same as for the energy. However, the wall pressure of a long wavelength disturbance of the largest growth just decays from its initial value, but for disturbances of shorter wavelength, it is also amplified
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| 35. |
- Bergström, Lars
(författare)
-
Self-sustained amplification of disturbances in pipe Poiseuille flow
- 1999
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Ingår i: European journal of mechanics. B, Fluids. - 0997-7546 .- 1873-7390. ; 18:4, s. 635-647
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Tidskriftsartikel (refereegranskat)abstract
- The nonlinear development of disturbances in pipe Poiseuille flow is studied with a low-dimensional model. The basic system from which the model is derived governs disturbances closely related to the radial velocity and radial vorticity disturbances. The analysis is restricted to the interaction of the two first harmonics of streamwise elongated disturbances since they are the most transiently amplified ones in linear theory. In the resulting dynamical system a nonlinear feedback from the normal vorticity disturbance (which is transiently amplified according to linear theory) to the radial velocity disturbance is present. Above a threshold of the initial amplitude, the feedback leads to a self-sustained amplification of the disturbances continuing for all times.
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| 36. |
- Bergström, Lars, et al.
(författare)
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Symmetry properties of developing three-dimensional laminar disturbances in plane Poiseuille flow
- 1994
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Ingår i: Physics of fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 6:4, s. 1618-1620
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of a finite-amplitude point-like laminar disturbance in plane Poiseuille flow is investigated using hot-wire anemometry. In contrast to earlier experiments, the initial disturbance was introduced simultaneously through both the upper and lower wall of the channel, resulting in an antisymmetric disturbance in the normal velocity. Although the initial disturbance mainly generated symmetrical streamwise velocity modes, the subsequent development of the perturbation showed a marked tendency for antisymmetry.
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| 37. |
- Bergström, Lars, et al.
(författare)
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The deuteron in high-energy physics
- 1980
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Ingår i: Reviews of Modern Physics. - 0034-6861 .- 1539-0756. ; 52:4, s. 675-697
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Tidskriftsartikel (refereegranskat)abstract
- The deuterium nucleus plays an important role in several branches of high-energy physics. We review its present status as a neutron source, a relativistic bound state, a collective six-quark state and a double scatterer.
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| 38. |
- Bergström, Lars
(författare)
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Transient growth of disturbances in laminar pipe flow
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transient growth of disturbances is studied theoretically in pipe Poiseuille flow and experimentally both in pipe and plane Poiseuille flow. The theoretical results, based on the initial value problem, show that a large transient amplification occurs for small, angular dependent disturbances in pipe Poiseuille flow although all modes are damped. The largest growth is obtained for disturbances with zero streamwise wave number and with an azimuthal periodicity of one. Only the streamwise disturbance component is then amplified and the energy density growth is proportional to the Reynolds number squared. For disturbances of finite axial wave number, also the radial and azimuthal disturbance components are amplified from their initial values but the growth is still dominated by the streamwise disturbance. When the azimuthal wave number increases the disturbance peak occurs at shorter times and the amplification decreases. However, for small times, larger azimuthal wave numbers dominate the growth. Asymptotic results for the most amplified disturbances show that two classes of modes can be distinguished and it is necessary to include modes from both classes to get amplification. The asymptotically derived propagation speeds of the two classes are in the ranges <2/3 times the centerline velocity (Ucl) and <0.818Ucl, respectively. If the nonlinear interaction of axially independent disturbances is considered, the results indicate that the amplification of the most linearly amplified disturbance is reduced. Laser Doppler measurements of the streamwise disturbance velocity due to radially induced initial disturbances of azimuthal periodicities (n) of one and five have also been conducted. The results show that the disturbance velocity in fact exhibits a transient growth. The disturbance with n=1 gives a slowly varying peak-value while the peak owing to an initial disturbance with n=5 shows a more rapid amplification to a maximum before it decays. The propagation speeds of the disturbance peaks are in the range theoretically expected for transiently amplified disturbances. By hot-wire measurements of the streamwise disturbance velocity due to two radially induced jet-like disturbances, the spatial structure of an evolving disturbance is investigated in detail. Especially the positive disturbance velocity exhibits an amplification followed by a decay. The disturbance also spreads and becomes streak-like and elongated in the streamwise direction. The spread implies that an integrated disturbance quantity grows to a peak and eventually decays. The propagation speed and the radial location of the disturbances agree with the theoretical findings for algebraically growing disturbances. In plane Poiseuille flow the symmetry properties of an evolving disturbance are investigated by means of hot-wire anemometry. The initial streamwise disturbance is designed to be symmetric with respect to the normal direction. Despite this, an antisymmetric structure develops in the region where the main amplification occurs as indicated by the theory.
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| 39. |
- Bergström, Lars
(författare)
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Transient properties of a developing laminar disturbance in pipe Poiseuille flow
- 1995
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Ingår i: European journal of mechanics. B, Fluids. - 0997-7546 .- 1873-7390. ; 14:5, s. 601-615
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Tidskriftsartikel (refereegranskat)abstract
- Hot-wire measurements of the velocity disturbance from point-like disturbances in a fully developed laminar pipe Poiseuille flow are performed. Two jets are induced radially into the pipe by diametrically opposed loud speakers. The resulting streamwise disturbance velocity component is investigated over the Reynolds number range 1550-2000. Close to the position of the initial disturbance, the disturbance amplitudes and gradients are large. After a few pipe radii the disturbance is reduced and consists of two small regions of positive disturbance with a larger region of negative disturbance in between. A downstream interval then follows in which the amplitudes of the regions with positive disturbance exhibit an amplification followed by a decay. The peaks of the two amplified regions are located at 0.6 radii and 0.4 radii, respectively, and propagate with velocities of 0.65 times the centreline velocity (Ucl) and 0.88 Ucl, respectively. Subsequently, the disturbance obtains an almost constant level, while it becomes elongated in the streamwise direction. The dominating part of the disturbance is then confined to a region around 0.5 radii from the centerline and the propagation velocity of the region with largest amplitude is in the range 0.7-0.8 Ucl. An integrated disturbance quantity is defined by integrating the square of the disturbance amplitude over the radius and time in a downstream position. In a position a few radii downstream, this quantity has decayed to about 10-20 per cent of the value obtained one pipe radius downstream. It is then amplified by a factor of about five before it finally decays
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| 40. |
- Bergström, Rune, et al.
(författare)
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Anaerob rening av barklakvatten.
- 1984
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Försök att behandla barklakvatten genom att recirkulera detta över en begränsad del av upplagets yta har utförts i pilotskala vid Skoghallsverkens barkupplag. Försöken visar att det är möjligt att med konventionell biologisk behandling nå jämförbara reningsresultat med ett filter som enbart upptar ett fåtal procent av upplagets yta. Filtret kan stabilt belastas med minst 0,25 kg COD/m3,d. och kräver inga kemikalietillsatser. För att undvika att den hydrauliska belasningen blir kapacitetsbestämmande krävs dock att barkbädden förstärks med ett inert och lätt material.
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| 41. |
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| 42. |
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| 43. |
- Bergström, Reinhold, et al.
(författare)
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Organizational foundations and closures in a regulated environment : Swedish commercial banks 1831-1990
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This study analyzes the foundations and closures of the total population of Swedish commercial banks in 1831-1990 using both semi-parametric and parametric event-history methods. With reference to the comparatively rigid control of entries and exits in banking, five hypotheses are formulated: (1) acquisitions constitute the principal reason for closure in banking; (2) the early years are less hazardous for banks than for members of other industries; (3) the survival patterns of banks are related to the freedom of banking operations; (4) the survival rates of banks are positively related to the general economic activity at the time of foundation; and (5) the survival rates of banks are negatively related to the degree to which customer relationships already exist. The findings support the first, second, third and fifth hypotheses; some evidence also favours the fourth hypothesis
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Bergström, Tomas, et al.
(författare)
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Välfärdsstaden
- 1993
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Ingår i: Lokal makt. - 9179662358
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Abstract is not available
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| 48. |
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| 49. |
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| 50. |
- Friberg, Bertil, 1950, et al.
(författare)
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On cutting torque measurements during implant placement: a 3-year clinical prospective study.
- 1999
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Ingår i: Clinical implant dentistry and related research. - 1523-0899. ; 1:2, s. 75-83
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Evaluation of jaw bone quality at implant placement is mainly based on preoperative radiographic assessments and subjective hand registrations during implant site preparation. An objective technique with cutting torque measurements has been introduced, presenting an objective bone quality or bone hardness value of individual implant sites. PURPOSE: The purpose of this study was to evaluate cutting torque measurements during implant placement and to compare these values in different regions in mandibles and maxillae. The objective was to identify implants at risk for failing at implant placement. MATERIAL AND METHODS: Cutting torque measurements were performed during placement of Mk II self-tapping implants (Brånemark System) in 105 patients, comprising 72 edentulous (40 maxillae) and 34 partially edentulous (22 maxillae) jaws. A total of 523 implants were inserted, of which 420 were of the Mk II design and of which 412 were subjected to cutting torque measurements. Statistical analyses were performed by comparing cutting torque values of maxillae and mandibles and of different jaw regions. Cutting torque values were also correlated with radiographically and clinically assessed bone quality scores. Patients were followed clinically for a minimum of 3 years. RESULTS: A statistically significant difference in cutting torque values of maxillae and mandibles was seen, although not when comparing anterior and posterior regions within the same jaws or of different jaws. Significant correlations were found between values of cutting torque and bone quality. The majority of failures were seen in bone of medium to high density, whereas implants inserted in bone of poor density presented a better outcome, perhaps due to an adapted surgical protocol and an extended healing period. The overall implant survival rate at 3 years was 95%, and when analyzing different jaw categories, survival rates of 92.0% and 99.4% were seen for edentulous maxillae and mandibles, respectively. The corresponding figures for partially edentulous jaws were 95.4% and 97.6%. CONCLUSION: It was not possible to identify sites at risk for future implant losses or to determine a lower limit value of cutting torque in order to achieve successful implant integration.
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