Search

Purpose: Treatment of secondary knee osteoarthritis with a significant extra-articular deformity can be challenging. In such cases, an osteotomy or a custom-made hinged knee arthroplasy (CMH) are treatment options. However, there are limited data on the outcomes of using CMHs. Thus, the aim of this retrospective study was to assess the clinical results and subjective outcomes of CMHs. Methods: We reviewed 9 CMHs (Endo-Model, LINK) in 7 patients with a minimum of 2-year follow-up. Upon the last follow-up, we evaluated MA, stability and range of movement (ROM). Oxford Knee Score (OKS) was used to evaluate patient-reported outcomes. Results: The average age upon surgery was 61 years (48–76 years), and the follow-up period was 66 months. There were no early complications. Two CMHs were revised, one due to aseptic loosening and one due to late-onset haematogenic infection. Pre-operatively, MA varied from 18° (average 11°) valgus-deformity to 30° (average 17°) varus-deformity. Post-operatively, 7/9 (78%) of patients achieved better MA. Upon follow-up, the average OKS was 41/48, and ROM was 113°. Conclusions: Patients treated with CMHs achieved good clinical and patient-reported outcomes. There were no early reoperations, and revision rate was relatively low. Overall, CMH could be considered for low-demand patients with increased operative risks. [ABSTRACT FROM AUTHOR]

Free surface waves were examined both in superfluids $$^3$$ He and $$^4$$ He with the premise that these inviscid media would represent ideal realizations for this fluid dynamics problem. The work in $$^3$$ He is one of the first of its kind, but in $$^4$$ He, it was possible to produce a much more complete set of data for meaningful comparison with theoretical models. Most measurements were performed at the zero temperature limit, meaning $$T<$$ 100 mK for $$^4$$ He and $$T\sim $$ 100 $$\upmu $$ K for $$^3$$ He. Dozens of surface wave resonances, including up to 11 overtones, were observed and monitored as the liquid depth in the cell was varied. Despite of the wealth of data, perfect agreement with the constructed theoretical models could not be achieved. [ABSTRACT FROM AUTHOR]

A concentration-saturated helium mixture at the melting pressure consists of two liquid phases and one or two solid phases. The equilibrium system is univariant, whose properties depend uniquely on temperature. Four coexisting phases can exist on singular points, which are called quadruple points. As a univariant system, the melting pressure could be used as a thermometric standard. It would provide some advantages compared to the current reference, namely pure $$^3$$ He, especially at the lowest temperatures below 1 mK. We have extended the melting pressure measurements of the concentration-saturated helium mixture from 10 to 460 mK. The density of the dilute liquid phase was also recorded. The effect of the equilibrium crystal structure changing from hcp to bcc was clearly seen at $$T=294$$ mK at the melting pressure $$P=2.638$$ MPa. We observed the existence of metastable solid phases around this point. No evidence was found for the presence of another, disputed, quadruple point at around 400 mK. The experimental results agree well with our previous calculations at low temperatures, but deviate above 200 mK. [ABSTRACT FROM AUTHOR]

We describe the measurement principles to excite and detect surface waves on liquid helium at very low temperatures. We excited the waves mechanically by rocking the whole cryostat with frequencies of few hertz. The waves were detected capacitively with an interdigital capacitor on a vertical wall of the cuboid experimental volume. In superfluid He at around 0.2 mK at least eleven surface resonances were observed below 11 Hz whereas in normal fluid only a few resonances were observable above 50 mK. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Dementia has been established as one of the major challenges of society. Dementia places an increasing burden on caregivers, and on health care and social welfare. The purpose was to determine the prevalence of dementia syndrome in an ageing rural population, and on the grounds of the results to discuss the development of the prevalence taking into consideration population ageing. Population and method: A total population based clinico-epidemiological study was carried out covering all of the 1680 inhabitants aged 60+ in the rural municipality of Haapajärvi in Northern Finland. Registers of health and social welfare, and population interviews using Mini Mental State Examination followed by clinical examinations for those scoring less than 25 points, were used for screening and diagnosing dementia, which was made according to the DSM-IV criteria. Results: Among all eligible subjects, 70.8% were participating in the study. The prevalence of dementia was 8.8% in a total population aged 60+. The prevalence was associated with advanced age giving the prevalence-rate of 43.8% among the people aged 90+. Discussion: The systematic auditing for dementia among the total population of people aged 60+ discovered new cases yielding higher prevalence numbers than found earlier in Finnish or in European studies. Conclusion: The results refer to the fact that active measures are needed in order to improve the access to diagnostics and care for the demented. Assuming no changes in mortality, and that no effective prevention strategies or curative treatment take place, the number of demented persons in the study area will increase due to the population development by 39% by the year 2020, and by 90% by the year 2030. [ABSTRACT FROM AUTHOR]

Proton magnetic resonance spectroscopy (1H MRS) neurometabolite abnormalities have been detected widely in subjects with and at risk for schizophrenia. We hypothesized that such abnormalities would be present both in patients with schizophrenia and in their unaffected twin siblings. We acquired magnetic resonance spectra (TR/TE=3000/30 ms) at voxels in the mesial prefrontal gray matter, left prefrontal white matter and left hippocampus in 14 twin pairs discordant for schizophrenia (2 monozygotic, 12 dizygotic), 13 healthy twin pairs (4 monozygotic, 9 dizygotic) and 1 additional unaffected co-twin of a schizophrenia proband. In the mesial prefrontal gray matter voxel, N-acetylaspartate (NAA), creatine+phosphocreatine (Cr), glycerophosphocholine+phosphocholine (Cho) and myo-inositol (mI) did not differ significantly between patients with schizophrenia, their unaffected co-twins or healthy controls. However, glutamate (Glu) was significantly lower in patients with schizophrenia (31%, percent difference) and unaffected co-twins (21%) than in healthy controls (collapsed across twin pairs). In the left hippocampus voxel, levels of NAA (23%), Cr (22%) and Cho (36%) were higher in schizophrenia patients compared with controls. Hippocampal NAA (25%), Cr (22%) and Cho (37%) were also significantly higher in patients than in their unaffected co-twins. Region-to-region differences in metabolite levels were also notable within all three diagnosis groups. These findings suggest that 1H MRS neurometabolite abnormalities are present not only in patients with schizophrenia, but also in their unaffected co-twins. Thus, reduced mesial prefrontal cortical Glu and elevated hippocampal NAA, Cr and Cho may represent trait markers of schizophrenia risk and, when exacerbated, state markers of schizophrenia itself. [ABSTRACT FROM AUTHOR]

We use a simple tight-binding (TB) model to study electronic properties of free graphene flakes. Valence electrons of triangular graphene flakes show a shell and supershell structure which follows an analytical expression derived from the solution of the wave equation for triangular cavity. However, the solution has different selection rules for triangles with armchair and zigzag edges, and roughly 40 000 atoms are needed to see clearly the first supershell oscillation. In the case of spherical flakes, the edge states of the zigzag regions dominate the shell structure which is thus sensitive to the flake diameter and center. A potential well that is made with external gates cannot have true bound states in graphene due to the zero energy band gap. However, it can cause strong resonances in the conduction band. [ABSTRACT FROM AUTHOR]

For rotating Bose-Einstein condensates, the occurrence of vortices has been much discussed in the Gross-Pitaevskii approach. Here, we study vortex formation in finite systems with few particles for weak and repulsive two-body interactions, by numerical diagonalization. Vortex formation is surprisingly similar for both (spinless) bosonic and fermionic particles. Breaking the rotational invariance of the Hamiltonian of the system reveals the vortex patterns. A transformation from a many-fermion to a many-boson state is proposed. [ABSTRACT FROM AUTHOR]

Magnetic properties of two and three-dimensional clusters of quantum dots are studied with exact diagonalization of a generalized Hubbard model. We study the weak coupling limit, where the electrons interact only within a quantum dot and consider cases where the second or third harmonic oscillator shell is partially filled. The results show that in the case of half-filled shell the magnetism is determined by the antiferromagnetic Heisenberg model with spin 1/2, 1 or 3/2, depending on the number of electrons in the open shell. For other fillings the system in most cases favors a large total spin, indicating a ferromagnetic coupling between the dots. [ABSTRACT FROM AUTHOR]

The treatment of fractures of the distal third of the tibia remains still controversial. It is often difficult to get and retain good reduction by non-operative or nailing methods. Open reduction and plate fixation offers good reduction and retention of the achieved position. However, increased soft tissue damage and high complication rate has led to search less invasive surgical methods such as minimal invasive plating technique. Lateral approach for the distal tibia allows to reduce and to plate both the fibula and the tibia using only one skin incision. We have used lateral approach for 20 consecutive tibia fracture patients and report clinical and radiological results after an average follow-up of 31 months. All fractures united, but two malunions were developed after good primary reduction. Seventeen patients achieved excellent or good subjective result while one had moderate and two poor results. Four superficial wound infections were noticed and they were treated conservatively. We conclude that lateral approach for the distal tibia is a demanding, but useful surgical method for treatment of the distal tibia fractures especially in cases where no medial comminution of the tibia is present and when the fibula has to be fixed, too. [ABSTRACT FROM AUTHOR]

We compare magnetism in two artificial lattice structures, a quantum dot array formed in a two-dimensional electron gas and an optical lattice loaded with repulsive, contact-interacting fermionic atoms. When the tunneling between the lattice sites is strong, both lattices are non-magnetic. With reduced tunneling in the tight-binding limit, the shell-filling of the single-site quantum wells combined with Hund's rule determines the magnetism. This leads to a systematic magnetic phase diagram with non-magnetic, ferromagnetic and antiferromagnetic phases. [ABSTRACT FROM AUTHOR]

Systematics of the melting transition for sodium clusters with 40-355 atoms has been studied with both ab initio and semiclassical molecular dynamics simulations. The melting temperatures obtained with an ab initio method for Na55+ and Na93+ correlate well with the experimental results. The semiclassically determined melting temperatures show similarities with the experimentally determined ones in the size region from 55 to 93 and near size 142, and the latent heat in the size region from 55 to 139, but not elsewhere in the size region studied. This indicates that the nonmonotonical melting behavior observed experimentally cannot be fully explained by geometrical effects. The semiclassically determined melting temperature and the latent heat correlate quite well, indicating that they respond similarly to changes in cluster geometry and size. Similarly, the binding energy per atom seems to correlate with the melting temperature and the latent heat of fusion. [ABSTRACT FROM AUTHOR]

The use of biological systems to remove contaminants from waste streams has been well documented. However, when dealing with complex waste streams, the use of one biological treatment system may not be the best alternative. When treating a complex waste stream, the use of “treatment trains” or “coupled systems” may be advantageous compared with any single biological technology. This article demonstrated that a coupled system was effective in biodegrading a chemically complex mixture of volatile organic compounds (VOCs). A bench-scale system consisting of a liquid bioreactor and a biofilter was used for the biodegradation of acetone, methanol, methyl ethyl ketone, naphthalene, alpha-pinene, and toluene. The bioreactor contained an inert solid support that immobilized a microbial population. The biofiltration portion of the system utilized the same microbial inoculum but employed Douglas fir bark as its solid support. Successful biodegradation of the complex VOC mixture was accomplished with this coupled system with an average VOC removal efficiency of 96% and VOC loading rates as high as 79 g/m3/h for inlet concentrations of > 8,000 ppmv. At elevated flow rates the liquid reactor demonstrated limited removal of some compounds, such as alpha-pinene and toluene, while maintaining excellent removal of other compounds, such as methanol and acetone. The biofilter portion of the system proved very successful in degrading the remaining toluene and alpha-pinene, thus complementing the removal from the bioreactor. This study demonstrates that coupled biological systems may be utilized for a chemically complex VOC-laden air stream that previously may not have been considered for biological treatment. [ABSTRACT FROM AUTHOR]

The effect of melting transition on the ionization potential has been studied for sodium clusters with 40, 55, 142, and 147 atoms, using ab initio and classical molecular dynamics. Classical and ab initio simulations were performed to determine the ionization potential of Na142 and Na147 for solid, partly melted, and liquid structures. The results reveal no correlation between the vertical ionization potential and the degree of surface disorder, melting, or the total energy of the cluster obtained with the ab initio method. However, in the case of 40 and 55 atom clusters, the ionization potential seems to decrease when the cluster melts. [ABSTRACT FROM AUTHOR]

Recently it was demonstrated that the rotational and vibrational spectra of quantum rings containing few electrons can be described quantitatively by an effective spin-Hamiltonian combined with rigid center-of-mass rotation and internal vibrations of localized electrons. We use this model Hamiltonian to study the quantum rings at finite temperatures and in presence of a nonzero magnetic field. Total spin, angular momentum and pair correlation show similar phase diagram which can be understood with help of the rotational spectrum of the ring. [ABSTRACT FROM AUTHOR]

Ground state geometries of small hard sphere clusters were studied using two different type of contact interaction, a pair-potential and a many-atom interaction. Monte Carlo method in an FCC lattice with all possible (111) stacking faults was used to obtain the minimum energy geometries for clusters up to 59 atoms. Due to the surface energy, FCC packing is generally favoured as opposite to the HCP structure. However, in most cluster sizes the ground state obtained with the many-atom interaction has one or more stacking faults. The most symmetric geometry is usually not the ground state. Clusters with 59 and 100 atoms were studied due the possibility of a high symmetry cluster with stacking faults in all four directions. The size dependence of the total energy has similarities with that of the average moment of inertia. [ABSTRACT FROM AUTHOR]

Exact many-body methods as well as current-spin-density functional theory are used to study the magnetism and electron localization in two-dimensional quantum dots and quasi-one-dimensional quantum rings. Predictions of broken-symmetry solutions within the density functional model are confirmed by exact configuration interaction (CI) calculations: In a quantum ring the electrons localize to form an antiferromagnetic chain which can be described with a simple model Hamiltonian. In a quantum dot the magnetic field localizes the electrons as predicted with the density functional approach. [ABSTRACT FROM AUTHOR]

Structural and electronic properties of small magnesium clusters ( N≤13) are studied using a first-principles simulation method in conjunction with the density functional theory and generalized gradient correction approximation for the exchange-correlation energy functional. It is observed that the onset of metallization of magnesium clusters is hard to assign since both the s- p hybridization and the energy gap between the valence and conduction bands do not evolve rapidly towards the known bulk properties. Instead these quantities show a slow and nonmonotonic evolution. [ABSTRACT FROM AUTHOR]

The ability of transforming growth factor-beta 1 (TGF-beta 1) to promote bone formation suggests that it may have potential as a therapeutic agent in bone defects. However, there still exists a need for an effective method of delivering TGF-beta 1 to the site of an osseous defect. In the present study, TGF-beta 1 was embedded in a bioabsorbable polymer paste (a blend of an L-lactide oligomer and a copolymer of epsilon-caprolactone and DL-lactide). The release of TGF-beta 1 from the polymer paste was examined in vitro with an enzyme-linked immunosorbent assay, which showed sustained release of active TGF-beta 1 over a 7-day period. Further, the polymer paste was used to fill a bone defect in the rat distal femur. The amount of TGF-beta 1 per rat was 50 micrograms, while in a control group we used an identical polymer paste without the growth factor. After a follow-up of 1 week and 3 weeks, the femurs were examined radiographically, histologically, histomorphometrically, microradiographically, and were also used for tetracycline-labeling studies. TGF-beta 1 did not enhance healing of the bone defect. A combination of growth factors would probably be a more potent osteoinductor than TGF-beta 1 alone. [ABSTRACT FROM AUTHOR]

The ability of transforming growth factor-β1 (TGF-β1) to promote bone formation suggests that it may have potential as a therapeutic agent in bone defects. However, there still exists a need for an effective method of delivering TGF-β1 to the site of an osseous defect. In the present study, TGF-β1 was embedded in a bioabsorbable polymer paste (a blend of an l-lactide oligomer and a copolymer of ℇ-caprolactone and dl-lactide). The release of TGF-β1 from the polymer paste was examined in vitro with an enzyme-linked immunosorbent assay, which showed sustained release of active TGF-β1 over a 7-day period. Further, the polymer paste was used to fill a bone defect in the rat distal femur. The amount of TGF-β1 per rat was 50 μg, while in a control group we used an identical polymer paste without the growth factor. After a follow-up of 1 week and 3 weeks, the femurs were examined radiographically, histologically, histomorphometrically, microradiographically, and were also used for tetracycline-labeling studies. TGF-β1 did not enhance healing of the bone defect. A combination of growth factors would probably be a more potent osteoinductor than TGF-β1 alone. [ABSTRACT FROM AUTHOR]

We study the magnetic coupling in artificial molecules composed of two and four laterally coupled quantum dots. The electronic ground-state configurations of such systems are determined by applying current spin density functional theory which allows to include effects of magnetic fields. While the ground-state of a two-dot molecule with strong enough inter-dot coupling tends to be antiferromagnetic with respect to the spins of the single dot components, we find that a square lattice of four dots has a ferromagnetic ground state. [ABSTRACT FROM AUTHOR]

We apply the current spin-density functional formalism (CSDFT) of Vignale and Rasolt to two-dimensional quantum dots in magnetic fields. Avoiding any spatial symmetry restrictions of the solutions, we find that a broken rotational symmetry of the electronic charge density can occur in high magnetic fields. [ABSTRACT FROM AUTHOR]

The possibility of the existence of a core-melted cluster is investigated. To this end, a pair potential is introduced, with the property that the solid state of the cluster is less dense than the liquid state. With this kind of potential, the cluster exhibits a quite unusual behavior. In addition to the known states, solid, liquid, and surface-melted, it can also be found in a “dense-liquid” phase (a disordered state appearing at low temperatures), a “core-melted” phase, and a “core-surface-melted” phase. In the core-melted phase, the external part of the cluster consists of atoms that are vibrating around regular crystalline sites, while the core atoms have much bigger mobility, sometimes exhibiting a diffusive motion. The phase diagrams for different parameters that enter in the model potential are analyzed. [ABSTRACT FROM AUTHOR]

Melting and multipole deformations of sodium clusters with up to 55 atoms are studied using an ab initio molecular dynamics method. The melting temperature regions for Na20, Na40, and Na55 + are estimated. The melting temperature region determined here for Na55 + agrees with the one determined experimentally. The dominating deformation type observed at the liquid phase for Na20 and Na40 is octupole deformation and for Na14 and Na55 + quadrupole deformation. [ABSTRACT FROM AUTHOR]

The temperature-depence of the ionization potential of Al6 and Al7 clusters is studied by using ab initio molecular dynamics. The threshold regions of theoretical photoionization efficiency curves are obtained from the calculated ionization potential distributions by integration and the determined ionization potentials are compared with the experimental ones. Two important effects, which complicate the determination of ionization potential from photoionization efficiency curves, are observed: the thermal tail effect and the isomerization. Also a link between the adiabatic ionization potential and the threshold of the photoionization efficiency curve is discussed. In the case of Al7, this often used connection breaks down. [ABSTRACT FROM AUTHOR]

The concept of shell structure has been found useful in the description of semiconductor quantum dots, which today can be made so small that they contain less than 20 electrons. We review the experimental discovery of magic numbers and spin alignment following Hund’s rules in the addition spectra of vertical quantum dots, and show that these results compare well to model calculations within spin density functional theory. We further discuss the occurrence of spin density waves in quantum dots and quantum wires. For deformable two-dimensional quantum dots (for example, jellium clusters on surfaces), we study the interplay between Hund’s rules and Jahn–Teller deformations and investigate the effect of magnetic fields on the ground-state shapes. [ABSTRACT FROM AUTHOR]

The ionization potential of sodium clusters (8 ≤ N ≤ 55) at a finite temperature is studied using density functional theory and ab initio molecular dynamics. The threshold regions of the photoionization efficiency curves are deduced from the integrated IP distributions, which are obtained from the energy eigenvalues of the highest occupied Kohn-Sham states during molecular dynamics by applying a theoretically well-defined shift. The calculated ionization potentials are directly compared to the experimental values. The energetically best geometry of Na55 is found to be a slightly distorted icosahedron. [ABSTRACT FROM AUTHOR]

Diffusion processes of adatoms on icosahedral and Wulff polyhedral aluminum cluster surfaces have been studied by molecular dynamics simulations using the effective medium theory. Activation energies of diffusion mechanisms along {111} and {100} facets and from one facet to another, including different hopping and exchange processes as well as more exotic events, have been calculated. Exchange diffusion of an adatom by a chain mechanism through a {100} facet between two {111} facets and hopping diffusion across the edge between two {111} facets via a pull of another adatom on the neighbour facet are shown to play an important role. Adatoms on {111} facets are mobile already at very low temperatures, but on {100} facets diffusion starts above the room temperature as well as diffusion from {111} facets to {100} facets. Diffusion from {100} facet to other facets was not observed until at temperatures close to the melting temperatures of clusters. Dynamical simulations at different temperatures confirmed the appearance of diffusion mechanisms predicted by the activation energies. [ABSTRACT FROM AUTHOR]

The odd-even staggering of free-electron metal clusters is studied using several simple models: Noninter-acting electrons in a rectangular box, triaxial harmonic oscillator, and Hückel model. Finite temperature effects are studied using the Monte Carlo method. All the models show qualitatively similar odd-even staggering. In the ground state the HOMO-LUMO gap is larger than the neighbouring energy gaps. The reduction of the odd-even staggering due to exchange and correlation is studied using the local-spin-density approximation. [ABSTRACT FROM AUTHOR]

Several simple models have been used to study the effects of the surface on the electronic shell structure in metal clusters. The main results are as follows: The icosahedral clusters have the same electronic shell structure as the sphere up to about 1000 atoms. The surface roughness causes the distribution of the level spacings to be a Wigner distribution. By varying the softness of the potential we can obtain potentials where the simplest classical orbits are the 'five-point star' or even the 'three-point star'. [ABSTRACT FROM AUTHOR]

The origin of the plasmon excitation in small metal clusters is studied within the jellium model through ab initio electronic-structure calculations based on the nuclear shell model. In the limit of infinite size, the plasmon classically represents pure harmonic motion of the center of mass of the valence electrons. It is shown that this limit is already well approximated by clusters of only eight electrons. [ABSTRACT FROM AUTHOR]

The lattice gas Monte Carlo and tight binding method is used to study the electronic shell structure in large metallic clusters. The average density of states of a large ensemble of deformed clusters shows the same shell structure as the most spherical geometry. The level spacing distribution at the Fermi level is a Wigner distribution. [ABSTRACT FROM AUTHOR]

We report molecular dynamics simulations of the impact of TiD clusters on TiD targets. In each cluster collision the total fusion probability seems to be due to a single deuterium deuterium collision. The kinetic energies of incident deuterium atoms gradually level off around the initial cluster energy, but do not reach the high energy tail of a corresponding Maxwell-Boltzmann distribution. Neither any other support for a thermonuclear fusion mechanism was observed. On the contrary, our simulations imply that the enhanced fusion rate is rather due to channeled many atom collision cascade type mechanism. [ABSTRACT FROM AUTHOR]

The Hückel model is used to study the electronic structure of monovalent metal clusters. In an fcc cluster the Hückel model gives an estimate to the electronic structure of a free electron cluster. It is shown that the surface faceting of the fcc cluster can destroy the electronic shell structure already when the cluster has about 100 electrons. In the Hückel model the icosahedral structure has smaller total energy than the fcc structures, from which the Wulff construction has the smallest energy already when the cluster has 600 atoms. [ABSTRACT FROM AUTHOR]

Magnetic properties of small antiferromagnetic clusters have been studied by using the Ising model with nearest-neighbour interactions. The number of atoms in the clusters varied between 6 and 30. Several cluster geometries were analysed in detail with the result that there is no generic phase diagram. In an external magnetic field magnetisation can increase with increasing temperature in a considerable temperature range. Magnetisation was found to strongly depend on both the overall geometry of the cluster and on the symmetry of the underlaying lattice structure. [ABSTRACT FROM AUTHOR]

The shapes of metal clusters (with 2 to 14 valence electrons) on an inert surface are studied with a simple model based on the ultimate jellium model. It is shown that within certain approximations the surface-cluster interaction can be described with an external potential in the Kohn-Sham method. No restrictions for the cluster geometry are imposed. The results show that depending on the strength of the interaction and on the size of the cluster, the ground state is either planar or three-dimensional, but in many cases both geometries are stable and there is a marked energy barrier between them. The results agree qualitatively with ab initio calculations of Na clusters on a NaCl(100) surface. [ABSTRACT FROM AUTHOR]

Equilibrium geometries of quasi two-dimensional jellium systems are calculated in the local density approximation, closely following the 'Ultimate Jellium Model' of [1]. The background charge is assumed to be fully deformable in a layer between two parallel planes, whereas the wave functions in the direction perpendicular to such a 'jellium slice' are confined to their ground state. Like for jellium clusters in three dimensions [1], we find that for various system sizes, a trend towards a breaking of axial and inversion symmetries is observable. [ABSTRACT FROM AUTHOR]

The local spin-density approximation is used to calculate ground- and isomeric-state geometries of jellium clusters with 2 to 22 electrons. The positive background charge of the model is completely deformable, both in shape and in density. The model has no input parameters. The resulting shapes of the clusters exhibit breaking of axial and inversion symmetries; in general the shapes are far from ellipsoidal. Those clusters which lack inversion symmetry are extremely soft against odd-multipole deformations. Some clusters can be interpreted as molecules built from magic clusters. The deformation produces a gap at the Fermi level. This results in a regular odd-even staggering of the total energy per electron and of the HOMO level. The strongly deformed 14-electron cluster is semimagic. Stable isomers are predicted. The splitting of the plasmon resonance due to deformation is estimated on a classical argument. [ABSTRACT FROM AUTHOR]

Using the density functional Kohn-Sham method we show that the internal shapes of fermion clusters are nearly independent of the interparticle interactions. The odd-even staggering of the total energy of small nuclei and of sodium clusters are shown to be of the same origin. Tetrahedral deformations are predicted for 40, 70 and 112 atom sodium clusters. An alternative model for linear nuclei is suggested. [ABSTRACT FROM AUTHOR]

The tissue-implant interface at a self-reinforced poly-L-lactide (SR-PLLA) expansion plug implanted in distal rabbit femoral cancellous bone was studied histologically, histomorphometrically, and microradiographically in 35 rabbits during consolidation of a transverse transcondylar osteotomy fixed with the SR-PLLA expansion plug. The absorbable plug for internal fixation of fractures and osteotomies measured 4.5 mm in diameter and 30 mm in length and had an expandable distal locking blade system. The femoral specimens were harvested in groups of 5-10 rabbits after a follow-up time of 3, 6, 12, and 24 weeks. The intact contralateral femur served as a control. Vigorous osteogenic response to the implant was already observed at 3 weeks postoperatively, and the osteoid surface fraction at 24 weeks was still significantly higher than in the unoperated contralateral femur. Incomplete union of the osteotomy seemed to result in increased fibrous tissue formation at the tissue-implant boundary. No signs of degradation of the SR-PLLA was observed within the entire follow-up period. The number of inflammatory cells at the tissue-implant interface was low. Consequently, the short-term biocompatibility of the implant was deemed acceptable. Clinical application of the expansion plug is being planned. [ABSTRACT FROM AUTHOR]

Of all the 95 primary tracheal carcinomas diagnosed in Finland in 1967-1985, 72% were squamous cell carcinomas. Fifty-three percent were located in the lower third of the trachea. Main symptoms were dyspnea, cough and hemoptysis. Fifty-nine percent of the patients developed extratracheal growth during the follow-up of 12 years, with lungs, neck, liver, and bones being the most common sites. In addition, autopsy revealed mediastinal metastases in 25% of patients. Vocal cord palsy at the time of diagnosis was present in 33%. The size and location of tumor in the trachea did not affect survival significantly. Patients with adenoid cystic carcinomas had the best prognosis. [ABSTRACT FROM AUTHOR]

The electronic structure of positively charged sodium cluster with 59 atoms and negatively charged sodium cluster with 57 atoms (both having 58 electrons) have been studied using an ab initio molecular dynamics method. Although the geometries of both clusters are nearly spherical, the results show differences in the electronic shells. [ABSTRACT FROM AUTHOR]

We study the dependence of the classical plasmon frequency on the symmetry of the metal cluster and show that all clusters with at least two three-fold axes have the same plasmon frequency as the spherical cluster, ω/√3. In these cases the effect of the geometry will only appear in the spill-out correction and in other quantum mechanical corrections. [ABSTRACT FROM AUTHOR]

Molecular dynamics is used to study the melting and structural transitions of small copper clusters. The melting temperature is found to be proportional to the average coordination number. Small icosahedral clusters melt at slightly higher temperatures than the cubic structures. Small cuboctahedral clusters are not stable but transform via a nondiffusive transition to icosahedral structure. [ABSTRACT FROM AUTHOR]

We apply the nuclear shell model to jellium clusters of up to twenty-one Na atoms. Binding energies, ionization potentials, and photoabsorption cross sections are calculated and compared with mean-field results. [ABSTRACT FROM AUTHOR]

A total of 167 feet in 125 patients were treated with a proximal osteotomy of the first metatarsal for hallux valgus. In addition, in 115 feet a resection of the base of the proximal phalanx was conducted, and in 25 feet the head of some lesser metatarsal bone was resected. Eight years (range 5–10 years) postoperatively the patients were sent a questionnaire concerning the present state of their feet. In all, 105 patients (142 feet) replied, and 63% stated that they felt no pain in their feet at all. Indeed, 86% of the patients indicated that, everything considered, the operation was worthwhile. The most common complaint was the difficulty of finding shoes to fit; 22.5% of the patients stated that they had a hard time with this. The average preoperative metatarsophalangeal angle was 38°, reduced by 22° postoperatively. The average preoperative first intermetatarsal angle was 15°, reduced by 5° after the operation. In the statistical analysis, no correlation between the preoperative body mass index, the hallux angle, the first intermetatarsal angle, the reduction achieved in the above mentioned angles by the operation, and patient satisfaction was found. [ABSTRACT FROM AUTHOR]

The electronic structure of positively charged sodium cluster with 59 atoms and negatively charged sodium cluster with 57 atoms (both having 58 electrons) have been studied using an ab initio molecular dynamics method. Although the geometries of both clusters are nearly spherical, the results show differences in the electronic shells. [ABSTRACT FROM AUTHOR]