Instabilities of rotating inclined buoyancy layers.

The boundary layer near a cooled inclined plate, which is immersed in a stably stratified fluid rotating about an axis parallel to the direction of gravity, is a model for katabatic flows at high latitudes. In this paper the base flow of such an inclined buoyancy layer is solved analytically for arbitrary Prandtl numbers. By applying linear stability analyses, five unstable modes are identified for both the fixed temperature and the isoflux boundary conditions, i.e., the stationary longitudinal roll (LR) mode, the oblique roll with low streamwise wave-number (OR-1) and high streamwise wave-number (OR-2) modes, and the Tolmien-Schlichting (TS) wave with low streamwise wave-number (TS-1) and high streamwise wave-number (TS-2) modes. It is indicated that the Coriolis effect induced by the rotation leads the critical modes to be three dimensional, and a larger tilt angle of the plate and stronger Coriolis effect cause both TS wave modes to be more unstable for both thermal boundary conditions. When the Coriolis effect is considered, the OR-1 and OR-2 modes are the most unstable mode at low and high tilt angles, respectively, but the TS-1 wave mode may be the most unstable one when the plate is nearly vertical. In addition, the spanwise phase velocities of the TS wave modes change directions as the tilt angle passes some threshold values for both thermal boundary conditions except for the TS-1 wave mode with a fixed temperature boundary condition, which propagates in the same spanwise direction for all explored tilt angles.

Geometry effects on Rayleigh-Bénard convection in rotating annular layers.

Rayleigh-Bénard convection is investigated in rotating annular cavities at a moderate dimensionless rotation rate Ω=60. The onset of convection is in the form of azimuthal traveling waves that set in at the sidewalls and at values of the Rayleigh number significantly below the value of the onset of convection in an infinitely extended layer. The present study addresses the effects of curvature and confinement on the onset of sidewall convection by using three-dimensional spectral solutions of the Oberbeck-Boussinesq equations. Such solutions demonstrate that the curvature of the outer boundary promotes the onset of the wall mode, while the opposite curvature of the inner boundary tends to delay the onset of the wall mode. An inner sidewall with a radius as low as one tenth of its height is sufficient, however, to support the onset of a sidewall mode. When radial confinement is increased the two independent traveling waves interact and eventually merge to form a nearly steady pattern of convection.

Nonlinear Rayleigh-Taylor instability of rotating inviscid fluids.

It is demonstrated theoretically that the nonlinear stage of the Rayleigh-Taylor instability can be retarded at arbitrary Atwood numbers in a rotating system with the axis of rotation normal to the acceleration of the interface between two uniform inviscid fluids. The Coriolis force provides an effective restoring force on the perturbed interface, and the uniform rotation will always decrease the nonlinear saturation amplitude of the interface at any disturbance wavelength.

Tumor suppressor TNFAIP3 (A20) is frequently deleted in Sézary syndrome.

Despite recent therapeutic improvements, the prognosis for patients suffering from Sézary syndrome (SS), a disseminated form of cutaneous T-cell lymphomas, is still poor. We identified bi- and monoallelic deletions of the tumor necrosis factor-α-induced protein 3 gene (TNFAIP3; A20) in a high proportion of SS patients as well as biallelic A20 deletion in the SS-derived cell line SeAx. Furthermore, we demonstrate that inhibition of A20 activates the NF-κB pathway thereby increasing the proliferation of normal T lymphocytes. On the other hand, the reconstitution of A20 expression slowed down the cell cycle in SeAx cells. Recently A20 inactivation has been reported in various B-cell lymphomas. In this study, we show that A20 is also a putative tumor suppressor in the T-cell malignancy-SS.

Homologous onset of double layer convection.

The onset of convection in two superimposed fluid layers of the same height is considered. It is found that the neutral curve for R(a) for the onset Rayleigh number R in dependence on the wave number a is an invariant of a multidimensional parameter space of property ratios of the system even though the corresponding convection solutions may vary strongly with these property ratios. For each neutral curve R(a) two manifolds of solutions are found one of which can be understood on the basis of symmetry properties of the system, while the other does not exhibit simple symmetry features. In particular the neutral curves R(a) for various single Rayleigh-Bénard convection layers are shown to correspond to two two-dimensional manifolds of solutions. Analytical expressions for the latter are derived in the case of outer stress-free boundary conditions.

[Free axillary flaps: a versatile area for harvesting of plicable flaps with a nearly undetectable scar]. / Freie, mikrovaskuläre axilläre Lappenplastiken - vielseitig verwendbar, gut formbar und narbenarmer Hebedefekt.

BACKGROUND: This article is about 7 cases of free axillary flaps based on the lateral thoracic vessels. PATIENTS AND METHODS: Preoperative ultrasound markings were performed. Indications were defects which needed very smooth and plicable flaps for coverage with a short and well detectable scar. RESULTS: Flap loss was not noticed, dissection was demanding due to the very small venous drainage of the flaps and took all over 6.5 hours. A comparison with standard flaps of the subscapular vascular system is given. CONCLUSIONS: The authors recommend the free axillary flap based on the lateral thoracic vessels as a versatile flap for special indications.

Reorientation of a hexagonal pattern under broken symmetry: the hexagon flip.

An unexpected pattern transition has been found experimentally in the transformation from hexagons to stripes caused by an applied anisotropy effect. The particular system studied is the surface instability of a horizontal layer of magnetic liquid in a tilted magnetic field. Two orthogonal Helmholtz pairs of coils provide a vertical and a tangential magnetic field. Whereas the vertical component destabilizes the flat layer, the tangential one preserves its stability. The ensuing surface patterns comprise regular hexagons, anisotropic hexagons, and stripelike ridges. The phase diagram for the tilted field instability is measured using a radioscopic technique. The investigation reveals an interesting effect: the flip from one hexagonal pattern to another under an increasing tangential field component, which is explained in terms of amplitude equations as a saddle-node bifurcation.

Evaluation of patients' opinion and metabolic control after transfer of young adults with type 1 diabetes from a pediatric diabetes clinic to adult care.

BACKGROUND: Transferring adolescents with diabetes from pediatric to adult care remains a challenge and the outcome is often unknown. The aims of this study were to determine the patients' perception of transfer arrangements and to analyze health care use and metabolic control. METHODS: A telephone questionnaire was conducted for patients who had been transferred from the pediatric clinic to adult care between 1995 and 2003. Of 161 identified patients, 101 (58 females, 43 males, mean age 22.1 +/- 2.4 years) were interviewed. Pediatric case notes and, if available (n = 44), current notes were analyzed to validate answers from the interview. RESULTS: After transfer, 52.5% of patients changed their health care provider at least once. The mean frequency of changes was 1.47. There was a significant decrease in clinic attendance rate after transition (8.5 +/- 2.3/years vs. 6.7 +/- 3.2/years). Patients criticized the lack of arrangements, poor information about transfer and the specific age for transition (18 years) set by legislation. The transfer was considered a negative experience by 58 patients. The patients assumed their metabolic control (HbA1c) was better than it really was (7.5 +/- 1.3% vs. 8.3 +/- 1.6%, p < 0.05). Actual HbA1c from case notes pre- and post-transfer did not change significantly (8.5 +/- 1.5% vs. 8.4 +/- 1.7%, n = 44, p = 0.441). CONCLUSION: The establishment of transition clinics and closer cooperation between specialists in pediatric and adult medicine is mandatory. Such changes are demanded by patients and would ensure better uptake of health care services after transfer.

Square patterns in rotating Rayleigh-Bénard convection.

The Küppers-Lortz instability occurs in rotating Rayleigh-Bénard convection and is a paradigmatic example of spatiotemporal chaos. Since the steady state of convection rolls is unstable to disturbance rolls oriented with an angle of about 60 degrees with respect to the given rolls in the prograde direction [G. Küppers and D. Lortz, J. Fluid Mech. 35, 609 (1969)], a spatiotemporally chaotic pattern is realized with patches of rolls continuously replaced by other patches in which the roll axis is switched by about 60 degrees. Surprisingly and contrary to this established scenario, Bajaj [Phys. Rev. Lett. 81 (1998)] observed experimentally square patterns in a cylindrical layer in the range of parameters where Küppers-Lortz instability was expected. In this paper we present square patterns which we have obtained in a numerical study by taking into account realistic boundary conditions. The Navier-Stokes and heat transport equations have been solved in the Oberbeck-Boussinesq approximation. The numerical method is pseudospectral and second order accurate in time. The rotation velocity of the square pattern increases linearly with the control parameter epsilon=Ra/R a(c) -1 , as in the experiment of Bajaj Furthermore, it was observed that this velocity decreases when the aspect ratio of the cylinder increases. These results indicate that the square pattern appears when the flow is laterally confined. The range of epsilon for which this pattern is stable tends to vanish for more extended layers.

On thermal convection in slowly rotating systems.

The dynamical properties of convection patterns in a fluid layer heated from below and rotating slowly about a horizontal axis are reviewed. Applications to the equatorial regions of planetary and stellar atmospheres are emphasized. Attention is drawn to the wavelike drift of hexagonal convection cells in the azimuthal direction and to the mean flow generated by all convection patterns except for rolls aligned with the axis of rotation.

Drifting convection cells in rotating fluid layers heated from below.

It is shown that hexagonal convection cells in a rotating horizontal fluid layer heated from below will in general exhibit a drift in contrast to convection rolls except in the case of a vertical axis of rotation. The direction of the drift is prograde (retrograde) for cells with rising (descending) motion in the center of the convection cell. In addition a mean flow generated by convection is derived. An application to solar convection is discussed.

Large scale structures in Rayleigh-Bénard convection at high Rayleigh numbers.

Direct numerical simulations of Rayleigh-Bénard convection in a plane layer with periodic boundary conditions at Rayleigh numbers up to 10(7) show that flow structures can be objectively classified as large or small scale structures because of a gap in spatial spectra. The typical size of the large scale structures does not always vary monotonically as a function of the Rayleigh number but broadly increases with increasing Rayleigh number. A mean flow (whose average over horizontal planes differs from zero) is also excited but is weak in comparison with the large scale structures. The large scale circulation observed in experiments should therefore be a manifestation of the large scale structures identified here.

Theoretical study of flow coupling mechanisms in two-layer Rayleigh-Bénard convection.

Rayleigh-Bénard convection in a system of two superimposed immiscible fluids, heated from below, is investigated theoretically. In a two-layer system, stationary convection is characterized by two distinct modes of flow coupling, namely, thermal coupling and viscous coupling. We derive two coupled amplitude equations in order to describe the nonlinear interaction of the viscous and the thermal coupling modes, whereby we restrict our analysis to the two-dimensional case. By analyzing the amplitude equations for varying fluid parameters, we make predictions concerning the stability of the involved coupling modes in the weakly nonlinear regime.

[Scapholunate dissociation: treatment by dorsal capsulodesis]. / Die skapholunäre Bandverletzung. Therapie durch dorsale Kapsulodese.

Between December 1994 and December 1996, 26 patients with a scapholunate ligament injury (three with SLD 1. degrees, 16 with SLD 2. degrees and 7 with SLD 3. degrees ) underwent an operation for dorsal capsulodesis in the Klinik für Handchirurgie, Bad Neustadt/Saale. Mean follow-up was 24 months (16 to 37 months). Follow-up criteria were range of motion, grip strength, pain relief, and X-ray findings. Clinical outcome was evaluated using a personal questionnaire, the DASH- and a modified Cooney-Score. Although significant reduction of joint mobility compared to the opposite site was found in all cases (E/F 32 %, U/R 19 %), the reduction of pain was 30 %. Grip-strength was not altered. Thus, 86 % of the patients were satisfied with the result obtained. On X-ray, the scapholunate angle was raised in the SLD 3. degrees -group by 12 degrees postoperatively; in the group with dynamic instability, X-ray findings were normal. Overall, 19 % (5/26) needed further operations due to persistent pain.

Instability of a thin film flowing on a rotating horizontal or inclined plane.

In this paper the instability of a thin fluid film flowing under the effects of gravity, Coriolis, and centrifugal forces is investigated. It is supposed that the film flows far from the axis of rotation on a plane which may be horizontal or inclined with respect to the horizontal. In the former case, the flow is only driven by the centrifugal force while in the latter case, the flow is driven by the components of centrifugal force and gravity along the plane. This case may also be considered as the flow down a rotating cone but far from the apex. The stabilizing influence of rotation on the film flow increases with the rotation rate. Up to a certain critical rate of rotation, the film flowing down the rotating inclined plane (or cone) is more stable than the flow on the horizontal rotating plane while above this rate of rotation the situation is reversed. The instability above the critical rate is associated with a finite wave number in contrast to the vanishing wave number of the instability below the critical rate. The possibility of Ekman layer instabilities is also investigated. An equation describing the nonlinear evolution of surface waves is also obtained. Moreover, this equation is simplified for the case in which the amplitudes are very small. An equation including dissipation as well as dispersion is derived whose solutions may possess solitary waves, as in the case of similar equations considered in the literature. These solutions are likely to correspond to the solitary spiral waves observed in experiments.

Correlation between cortical theta activity and hippocampal volumes in health, mild cognitive impairment, and mild dementia.

Cognitive decline is known to be associated with both increased theta power over frontal regions and hippocampal atrophy. The aim of this study was to reveal the relation between these parameters in groups with mild dementia, mild cognitive impairment, and healthy control subjects. The authors examined a preliminary randomly selected sample of 39 right-handed subjects joining the Leipzig Longitudinal Study of the Aged, consisting of 17 normal elderly subjects, 12 patients with mild cognitive impairment, and 10 patients with mild dementia assessed by Clinical Dementia Rating. All subjects were between 75 and 85 years old (mean age, 78 years; standard deviation, 2.78 years) and underwent EEG and brain MRI. Mean spectral power densities were calculated, and hippocampal body volume was measured. Significant negative linear correlations between theta power over frontal regions and hippocampal volumes were found. The results support the assumption about a relationship between hippocampal atrophy and theta power, and may be helpful for a better understanding of the course of Alzheimer's disease.

Deficits in haptic perception and right parietal theta power changes in patients with anorexia nervosa before and after weight gain.

OBJECTIVE: Our goal was to investigate whether patients with anorexia nervosa (AN) show deficits in haptic exploration tasks before and after weight gain. METHOD: The haptic exploration tasks consisted of palpating the structure of six sunken reliefs in sequence with both hands, eyes closed. After each exploration, the structure was reproduced on a piece of paper. A 19-channel digital electroencephalogram (EEG; linked ears) was continuously recorded during rest and haptic tasks for 10 AN patients (females, mean age: 15.90) and 10 healthy controls (CO; females, mean age: 16.14). Mean spectral power density was calculated as the mean amplitude of the spectral lines of the theta band (4-8 Hz). The AN patients were examined again after weight gain (T(0) and T(1)). RESULTS: The reproductions submitted by the AN patients were of notably poorer quality than those of the CO. Reproduction quality was unchanged after weight gain and independent of body mass index and intelligence. Mean exploration time was similiar in AN patients and CO. The analysis of spectral EEG power of both groups showed significant decrease in power data in the theta frequency band during haptic exploration compared with the rest intervals. The comparison of the theta power between CO and AN patients during haptic exploration showed major differences between the groups in both T(0) and T(1). Theta power was lower in AN patients than in the CO over the right hemisphere and right parietal regions. DISCUSSION: The quality of reproduction of the haptic stimuli and the theta-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing of the right parietal cortex in AN patients even after weight gain.

Bounds on the convective heat transport in a rotating layer.

Previous bounds on the convective heat transport in a horizontal layer heated from below and rotating about a vertical axis have been improved through the use of separate energy balances for the poloidal and toroidal components of the velocity field. Because the additional constraint imposed for the solution of the variational problem for the extremalizing vector field leads to Euler-Lagrange equations which can no longer be solved analytically, numerical methods must be employed. A Galerkin scheme is introduced and the variational problem is solved in the case when stress-free conditions are assumed at the upper and lower boundaries. Results are presented as a function of the Rayleigh number and the rotation parameter for the Prandtl numbers P=7, 0.7, 0.1, and 0.025.

Grafting of fibroblasts isolated from the synovial membrane of rheumatoid arthritis (RA) patients induces chronic arthritis in SCID mice-A novel model for studying the arthritogenic role of RA fibroblasts in vivo.

The objective of this study was to verify whether isolated rheumatoid arthritis (RA) synovial fibroblasts induce chronic arthritis in SCID mice, in analogy to whole tissue pieces. Fibroblasts were isolated from the synovial membrane of four RA patients (or controls) by out-growth and repeated-passage culture. Following flow-cytometry characterization, 2x10(6)cells were transferred into the left knee joint of SCID mice. The development of arthritis was assessed by joint swelling and histological changes. Human and murine cytokines were measured in vitro in co-cultures (or Transwelltrade mark systems) of human and murine cells. Purified RA synovial fibroblasts, but not healthy synovial or skin fibroblasts, induced hu/mu arthritis within 6 weeks. In-vitro secretion of murine and human interleukin(IL)-6, as well as murine tumour necrosis factor (TNF)-alpha, indicated cross-activation between murine macrophages and human RA fibroblasts. Soluble-factor mechanisms proved more effective than cell-contact mechanisms. Purified RA fibroblasts can, alone, induce hu/mu SCID arthritis. The cytokine profile suggests that xenogeneic interaction between human fibroblasts and murine macrophages may determine the sequence of events leading to hu/mu arthritis.

New patterns of centrifugally driven thermal convection.

An experimental study is described of convection driven by thermal buoyancy in the annular gap between two corotating coaxial cylinders, heated from the outside and cooled from the inside. Steady convection patterns of the hexaroll and of the knot type are observed in the case of high Prandtl number fluids, for which the Coriolis force is sufficiently small. Oblique rolls and phase turbulence in the form of irregular patterns of convection can also be observed in wide regions of the parameter space.