End effects in low aspect ratio Taylor-Couette flow.

Taylor-Couette flow with a low aspect ratio cylinder suffers from end effects due to the finite-span of the gap between the cylinder sides and the secondary flow in the region below the inner cylinder. We experimentally explore these end effects by varying the cylinder aspect ratio between 6.67 and 40 for a range of wall gap widths and bottom gap heights. For these geometries, end effects (i.e. non-ideal Taylor-Couette flow) can be substantial due to both features of the finite-span and the bottom secondary flow. In some cases, the finite-span effects extended between 20% and 30% of the way into the Taylor-Couette flow region, and the secondary flow at the bottom accounted for nearly half of the total measured torque. By taking these effects into consideration, our high aspect ratio results agreed well with those obtained by Taylor (Taylor 1936 Proc. R. Soc. Lond. A 157, 546-564. (doi:10.1098/rspa.1936.0215)) at considerably higher aspect ratios. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (part 1)'.

Posterior implant removal in patients with thoracolumbar spine fractures: long-term results.

PURPOSE: Debate remains whether posterior implants after thoracolumbar spine fracture stabilization should be removed routinely or only in symptomatic cases. Implant related problems might be resolved or even prevented but removal includes secondary risks. The aim of this study was to evaluate safety, patient satisfaction and quality of life after implant removal. METHODS: A retrospective cohort study was performed concerning 102 patients that underwent posterior implant removal after stabilization of a traumatic thoracolumbar fracture between 2003 and 2015. Patients were invited to fill in SF-36, EQ-5D and RMDQ questionnaires after implant removal. Additionally, questions concerning satisfaction were presented. Cobb angles before and after removal were measured and in- or decrease of symptoms was gathered from hospital charts. RESULTS: Mean age at removal was 38 years and time from implant removal to questionnaire was approximately 7 years, 62 patients filled in the questionnaires. Complications were present in 8% and quality of life was reported as fairly good. Patients had less back pain related disability compared to chronic low back pain patients. After removal there was a kyphosis increase which did not correspond with worsened clinical outcome. Removal decreased most symptoms and even asymptomatic patients reported benefit in most cases. An increase of symptoms after removal was reported in 11% of patients. CONCLUSION: Implant removal is generally safe and provides high patient satisfaction. Overall, patients have a fairly good quality of life. Most symptomatic and asymptomatic patients report benefit from removal. However, low risks of complications and increase of symptoms have to be weighted for individual patients.

Analyzing Collaborative Governance Through Social Network Analysis: A Case Study of River Management Along the Waal River in The Netherlands.

Until recently, governmental organizations played a dominant and decisive role in natural resource management. However, an increasing number of studies indicate that this dominant role is developing towards a more facilitating role as equal partner to improve efficiency and create a leaner state. This approach is characterized by complex collaborative relationships between various actors and sectors on multiple levels. To understand this complexity in the field of environmental management, we conducted a social network analysis of floodplain management in the Dutch Rhine delta. We charted the current interorganizational relationships between 43 organizations involved in flood protection (blue network) and nature management (green network) and explored the consequences of abolishing the central actor in these networks. The discontinuation of this actor will decrease the connectedness of actors within the blue and green network and may therefore have a large impact on the exchange of ideas and decision-making processes. Furthermore, our research shows the dependence of non-governmental actors on the main governmental organizations. It seems that the Dutch governmental organizations still have a dominant and controlling role in floodplain management. This challenges the alleged shift from a dominant government towards collaborative governance and calls for detailed analysis of actual governance.

Combining safety and nature: a multi-stakeholder perspective on integrated floodplain management.

In The Netherlands, river management strategies and land use of floodplains have changed drastically over the last two decades. Due to an integrated and participatory planning style, many agricultural fields in floodplains were transformed to nature. The idea of "self-regulating nature" in the floodplains and policies such as Room for the River and WaalWeelde created more multifunctional and natural floodplains. In this way, during the planning phase, win-win situations were created between flood protection and nature. It was only later that obstacles occurred with regard to the maintenance of floodplains, mainly because of different perspectives of the stakeholders on how to reconcile flood protection and nature. Therefore this study focuses on the opinions of persons involved with 'future' floodplain management strategies, which have been divided into five themes: ·visions of floodplain management; ·collaborators in floodplain management; ·visions of nature and self-regulating nature; ·realization of Natura 2000 goals in floodplains; ·feasibility of the Cyclic Floodplain Rejuvenation (CFR) strategy. We interviewed various persons involved in river and nature management along the Waal River. Based on our findings, it is concluded that an integrated planning approach has not been incorporated into the maintenance strategies and programs and, as a result, new, innovative management strategies such as CFR are proving to be incompatible with 'static' regulations such as Natura 2000's conservation goals and flood protection norms. However, by exploring the responders' visions of nature, we found that the majority of them preferred a dynamic vision of floodplains and, for this reason, they have advocated for more flexibility in current policies related to river and nature management. Additionally, the respondents emphasized the importance of multi-stakeholder collaboration to realize the goal of cost-efficient floodplain management.

A viscoelastic model of shear-induced hemolysis in laminar flow.

We present measurements of human blood hemolysis caused by laminar shear stresses ranging from 50 to 500 Pa for exposure times extending from 60 to 300 s using a Taylor-Couette device. A viscoelastic model is proposed that captures the response of the red blood cells to shear stress. The model is based on well-established mechanical properties of the red blood cell membrane, and shows good agreement with data from the experiments presented here, as well as data from the existing literature. Two characteristic time scales are identified: a fast time scale corresponding to the relaxation time of the red blood cell membrane and a slow time scale that represents the onset of plasticity and is related to hemoglobin release from a damaged cell. The model proposed here collapses the available data over almost five orders of magnitude in exposure time and shear stresses up to 500 Pa.

Turbulent pipe flow at extreme Reynolds numbers.

Both the inherent intractability and complex beauty of turbulence reside in its large range of physical and temporal scales. This range of scales is captured by the Reynolds number, which in nature and in many engineering applications can be as large as 10(5)-10(6). Here, we report turbulence measurements over an unprecedented range of Reynolds numbers using a unique combination of a high-pressure air facility and a new nanoscale anemometry probe. The results reveal previously unknown universal scaling behavior for the turbulent velocity fluctuations, which is remarkably similar to the well-known scaling behavior of the mean velocity distribution.

Measurement of local dissipation scales in turbulent pipe flow.

Local dissipation scales are a manifestation of the intermittent small-scale nature of turbulence. We report the first experimental evaluation of the distribution of local dissipation scales in turbulent pipe flows for a range of Reynolds numbers: 2.4x10(4)

Heavy-metal concentrations in small mammals from a diffusely polluted floodplain: importance of species- and location-specific characteristics.

The soil of several floodplain areas along large European rivers shows increased levels of heavy metals as a relict from past sedimentation of contaminants. These levels may pose risks of accumulation in food webs and toxicologic effects on flora and fauna. However, for floodplains, data on heavy-metal concentrations in vertebrates are scarce. Moreover, these environments are characterised by periodical flooding cycles influencing ecologic processes and patterns. To investigate whether the suggested differences in accumulation risks for insectivores and carnivores, omnivores, and herbivores are reflected in the actual heavy-metal concentrations in the species, we measured the current levels of Zn, Cu, Pb, and Cd in 199 specimens of 7 small mammal species (voles, mice, and shrews) and in their habitats in a diffusely polluted floodplain. The highest metal concentrations were found in the insectivorous and carnivorous shrew, Sorex araneus. Significant differences between the other shrew species, Crocidura russula, and the vole and mouse species was only found for Cd. The Cu concentration in Clethrionomys glareolus, however, was significantly higher than in several other vole and mouse species. To explain the metal concentrations found in the specimens, we related them to environmental variables at the trapping locations and to certain characteristics of the mammals. Variables taken into account were soil total and CaCl(2)-extractable metal concentrations at the trapping locations; whether locations were flooded or nonflooded; the trapping season; and the life stage; sex; and fresh weight of the specimens. Correlations between body and soil concentrations and location or specimen characteristics were weak. Therefore; we assumed that exposure of small mammals to heavy-metal contamination in floodplains is significantly influenced by exposure time, which is age related, as well as by dispersal and changes in foraging and feeding patterns under influence of periodic flooding.

Turbulent flow in smooth and rough pipes.

Recent experiments at Princeton University have revealed aspects of smooth pipe flow behaviour that suggest a more complex scaling than previously noted. In particular, the pressure gradient results yield a new friction factor relationship for smooth pipes, and the velocity profiles indicate the presence of a power-law region near the wall and, for Reynolds numbers greater than about 400x103 (R+>9x103), a logarithmic region further out. New experiments on a rough pipe with a honed surface finish with krms/D=19.4x10-6, over a Reynolds number range of 57x103-21x106, show that in the transitionally rough regime this surface follows an inflectional friction factor relationship rather than the monotonic relationship given in the Moody diagram. Outer-layer scaling of the mean velocity data and streamwise turbulence intensities for the rough pipe show excellent collapse and provide strong support for Townsend's outer-layer similarity hypothesis for rough-walled flows. The streamwise rough-wall spectra also agree well with the corresponding smooth-wall data. The pipe exhibited smooth behaviour for ks+ < or =3.5, which supports the suggestion that the original smooth pipe was indeed hydraulically smooth for ReD< or =24x106. The relationship between the velocity shift, DeltaU/utau, and the roughness Reynolds number, ks+, has been used to generalize the form of the transition from smooth to fully rough flow for an arbitrary relative roughness krms/D. These predictions apply for honed pipes when the separation of pipe diameter to roughness height is large, and they differ significantly from the traditional Moody curves.

Thrust production and wake structure of a batoid-inspired oscillating fin.

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.

Reynolds number dependence of streamwise velocity spectra in turbulent pipe flow.

Spectra of the streamwise velocity component in fully developed turbulent pipe flow are presented for Reynolds numbers up to 5.7x10(6). Even at the highest Reynolds number, streamwise velocity spectra exhibit incomplete similarity only: while spectra collapse with both classical inner and outer scaling for limited ranges of wave number, these ranges do not overlap. Thus similarity may not be described as complete, and a region varying with the inverse of the streamwise wave number, k(1), is not expected, and any apparent k(-1)(1) range does not attract any special significance and does not involve a universal constant. Reasons for this are suggested.

Clinical effectiveness of conventional influenza vaccination in asthmatic children.

Influenza immunization rates among young asthmatics remain unsatisfactory due to persistent concern about the impact of influenza and the benefits of the vaccine. We assessed the effectiveness of the conventional inactivated trivalent sub-unit influenza vaccine in reducing acute respiratory disease in asthmatic children. We conducted a two-season retrospective cohort study covering the 1995-6 and 1996-7 influenza outbreaks in 22 computerized primary care practices in The Netherlands. In total, 349 patients aged between 0 and 12 years meeting clinical asthma-criteria were included; 14 children were lost to follow-up in the second season. The occurrence of physician-diagnosed acute respiratory disease episodes including influenza-like illness, pneumonia. bronchitis, bronchiolitis, asthma exacerbation and acute otitis media in vaccinated and unvaccinated children were compared after adjustments for age, prior health care and medication use. The occurrence of acute respiratory disease in unvaccinated children was 28% and 24% in the 1995-6 and 1996-7 season, respectively, and was highest in children under 6 years of age (43%). The overall pooled clinical vaccine effectiveness was 27% (95% confidence interval -7 to 51%, P = 0.11) after adjustments. A statistically higher vaccine protectiveness of 55% (95% CI 20-75%, P = 0.01) was observed among asthmatics under 6 years of age compared with -5% in older children (95% CI -81 to 39%). The occurrence of acute respiratory disease among asthmatic children during influenza epidemics is very high, notably in the youngest. Influenza vaccination may reduce morbidity in asthmatic infants and pre-school children. However, larger, preferably experimental, studies are needed to establish the benefits of vaccination, notably in older asthmatic children.

Quality of life in patients with diabetic foot ulcers.

PURPOSE: To compare Quality of Life (QoL) between diabetic patients with (former or present) and without foot ulcers. METHODS: Two patient groups of comparable age, sex distribution, type distribution and duration of diabetes were studied. Fourteen patients with former or present, but clinically stable diabetic foot ulcers (DFUs) were studied. The control group was 24 unknown patients with DFUs. None of the participants had other diabetic complications or conditions that would potentially affect QoL. A diabetic foot risk score and QoL were assessed. QoL was scored with the RAND-36, the Barthel Score (ADL) and the Walking and Walking Stairs Questionnaire (WSQ). RESULTS: Marked and significant differences were found in physical functioning (p < 0.001), social functioning (p < 0.05), physical role (p < 0.001) and health experience (p < 0.05) between the two groups with the RAND-36 and the four subscales of the WSQ (all p < 0.001). On all these scales, QoL was significantly poorer in the study group. A correlation was found between the risk scores and QoL (physical functioning and physical role Spearman's r: -0.66, -0.56 and WSQ -0.63, -0.64, -0.67 and 0.71, respectively). CONCLUSION: Presence or history of DFUs has a large impact on physical role, physical functioning and mobility. Physical impairments especially influenced QoL. Probably, QoL can be increased by providing attention that will enhance mobility and by giving advice about adaptations and special equipment.

Over-the-counter availability of antimicrobial agents, self-medication and patterns of resistance in Karachi, Pakistan.

To determine whether the free availability of antimicrobial agents leads to misuse through self-medication, a house-to-house semi-structured interview was held in three different socio-economic areas of Karachi, Pakistan. Of the 2348 households visited, 1342 (57%) participated; this included 9209 individuals. Three hundred and twenty-two (3.5%) had used one or more antimicrobial in the previous 4 weeks, equivalent to 43 agents per 1000 persons per month. The most frequently used agents were amoxycillin (16.7%), co-trimoxazole (15.7%), erythromycin (10.9%), ampicillin/cloxacillin (Ampiclox, 9.1%) and metronidazole (4.5%). Of these, 91.4% were prescribed by a physician, 2.3% were advised by a chemist and 6.3% were used as self-medication. Self-medication increased with socio-economic status. High levels of resistance were found to ampicillin, co-trimoxazole, chloramphenicol and erythromycin. If these high resistance levels are related to the high frequency of antimicrobial use, over-the-counter availability cannot be held responsible. Education of the medical profession seems to be the single most important tool to control misuse of antimicrobial agents. Innovative approaches for continuous medical education are urgently needed.

beta1-Integrins dominate cell traffic of leukemic cells in human bone-marrow stroma.

Migration patterns of leukemic cells in bone marrow are largely regulated by cell contacts between leukemic cells and stromal cells or extra-cellular matrix. The mechanism of this interaction with bone-marrow stromal cells was studied in a human in vitro model. Migration behavior of erythroleukemia cell line K562, derived from a patient with chronic myeloid leukemia, was compared with that of the erythroleukemia cell line HEL92.1.7 and the promyelocytic leukemia cell line HL60 from acute leukemias. Interaction varied between low binding affinity (K562) to intensive cell interaction (HEL92.1.7) followed by invasion into the stromal cell monolayer. Some of the HL60 cells adhered to stromal cells, while the remainder migrated into the stromal cell monolayer. The role of adhesion molecules in these cell interactions was determined. Distinct expression of beta1-integrins ICAM-1, CD44 and VCAM-1 was detected on the different cell lines. Inhibition studies pointed to a dominant role of VLA-4- and VLA-5-mediated interactions. K562 lacked VLA-4 and a low binding affinity of the VLA-5 on these cells resulted in an absence of binding to the bone-marrow stroma. These results indicate the VLA-5/fibronectin, VLA-4/fibronectin and the VLA-4/VCAM-1 interaction pathways between leukemic cells and bone-marrow stroma.

[Beneficial effect of exercise therapy in urinary incontinence in family practice depends largely on therapy compliance and motivation]. / Gunstig effect van oefentherapie bij urine-incontinentie in de huisartspraktijk vooral afhankelijk van therapietrouw en motivatie.

OBJECTIVE: Determining the factors which influence the success of training therapy in women suffering from urinary incontinence. DESIGN: Descriptive. SETTING: Thirteen general practices in Nijmegen and environs, the Netherlands. METHOD: A total of 110 women between 20 and 65 years old, suffering from urinary incontinence were examined by their general practitioners. Age, personality, parity, psychological features and type, duration, severity, beginning of the disease, as well as the presence of cystocele or prolapse were recorded. Women were asked about their own experiences regarding factors that influenced success. The treatment consisted of training of pelvic muscles in stress incontinence and bladder training in urge incontinence. Outcomes and compliance were measured 3 and 12 months after start of treatment by means of a so-called incontinence diary. RESULTS: After 3 months the mean frequency of urine loss per week diminished from 21 to 8, and after 12 months to 6 times. Compliance was the most important contribution to success. Patients were more motivated to practise when the subjective burden of the urine loss was more severe. Other features did not influence success.

The effects of treatment of urinary incontinence in general practice.

A total of 110 women who had reported urinary incontinence to their general practitioners were randomly assigned to a treatment or control group. Treatment consisted of pelvic floor exercises in the case of stress incontinence and bladder training in the case of urge incontinence. The results were measured after 3 and 12 months by a research assistant on the basis of a constructed severity scale, an incontinence diary, and a comparison by the patients themselves of their previous and current conditions. After 3 months the control group were given the same treatment. After a further 3 and 12 months, they were assessed in exactly the same way as the treatment group. After 3 months about 60% of the patients were either dry or only mildly incontinent; the mean number of wet episodes had gone down from 20 to 7, and 74% of the women felt improved or cured. These results were later corroborated by the control group. After 12 months this successful outcome was improved slightly further. It may be concluded that the majority of women with incontinence can be successfully treated by the general practitioner. The effect of this treatment continues after one year.

Relationship between the working styles of general practitioners and the health status of their patients.

The aim of this study was to relate the working style of general practitioners to the health status of a sample of their patients. From a large regional sick fund forming part of the national health insurance system in the Netherlands a stratified sample was taken of general practitioners with at least 1000 patients on their list, taking into account the degree or urbanization of the area in which they practised and their annual referral rates to specialists. These 75 general practitioners were observed for two days in their surgeries by trained doctors and rated according to criteria defined beforehand. Taking into account these ratings and the annual figures from the sick fund for prescribing selected drugs and referrals to specialists, the general practitioners were classified into styles of practice - integrated, interventionist or minimal diagnostic. Twenty randomly selected women, aged 50-65 years, from each general practitioner's list, were interviewed and examined by independent doctors. The patients of general practitioners with the integrated practice style appeared to feel more healthy and to have more realistic expectations about the possibilities of professional help for common ailments. They tended to visit their doctor less frequently and to have fewer symptoms. The results showed an association between the quality of general practitioners and patients' health, and it may therefore be concluded that good general practitioners can further the health and well being of their patients.