Field-Induced Breakup of Emulsion Droplets Stabilized by Colloidal Particles

We simulate the response of a particle-stabilized emulsion droplet in an external force field, such as gravity, acting equally on all $N$ particles. We show that the field strength required for breakup (at fixed initial area fraction) decreases markedly with droplet size, because the forces act cumulatively, not individually, to detach the interfacial particles. The breakup mode involves the collective destabilization of a solidified particle raft occupying the lower part of the droplet, leading to a critical force per particle that scales approximately as $N^{-1/2}$.Comment: 4 pages, plus 3 pages of supplementary materia

Whose security? Whose justice?:Customary authorities in security and justice interventions in the Horn of Africa

An evolving body of literature calls for politically realistic security and justice interventions that reflect the plurality of norms, power and legitimacy in the security and justice arena. In this arena, customary authorities may provide more security and justice than the state, especially in Sub-Saharan Africa. They matter for peace, security, and development, but engaging them requires donors to navigate hidden power structures and illiberal traditions and ideas. In response to this complexity, this article proposes an approach for working with customary authorities – supporting fluid networks of customary, community and state agents and the political bargaining between them. Looking at a specifically conflict-affected area of the Horn, this paper provides an important survey of what we know, and what we don’t know and embraces customary authorities’ agency in change

Assessing sensitivity to change: choosing the appropriate change coefficient

The past 20-years have seen the development and evaluation of many health status measures. Unlike the high standards demanded of those who conduct and report clinical intervention trials, the methodological rigor for studies examining the sensitivity to change of health status measures are less demanding. It is likely that the absence of a criterion standard for change in health status contributes to this shortcoming. To increase confidence in the results of these types of studies investigators have often calculated multiple change coefficients for the same patient sample. The purpose of this report is to identify the conflict that arises when multiple change coefficients are applied to the same patient sample. Three families of change coefficients based on different assumptions concerning the sample composition are identified: (1) the sample is homogeneous with respect to change; (2) subgroups of patients who truly change by different amounts exist; (3) individual patients, many of whom truly change by different amounts exist. We present several analyses which illustrate a major conceptual conflict: the signal (a measure\u27s true ability to detect change) for some of these coefficients appears in the noise term (measurement error) of the others. We speculate that this dilemma occurs as a result of insufficient preparatory work such as pilot studies to establish the likely change characteristic of the patient population of interest. Uncertainty in the choice of change coefficient could be overcome by conducting pilot studies to ascertain the likely change characteristic of the population of interest. Once the population\u27s change characteristic is identified, the choice of change coefficient should be clear

Pattern of recovery following total shoulder arthroplasty and humeral head replacement

BACKGROUND: Understanding the pattern of recovery and expected rate of change after shoulder arthroplasty is helpful to clinicians and patients for setting realistic expectations and goals. The purpose of this study was to describe the pattern of recovery over a 2-year period for patients receiving either a Total Shoulder Arthroplasty (TSA) or Humeral Head Replacement (HHR). METHODS: This was a secondary analysis of prospectively collected data of patients who had undergone TSA or HHR and were followed for up to 2 years. Patients were seen prior to surgery and at 6 months, one year and two years after surgery and completed the American Shoulder and Elbow Surgeon’s (ASES) questionnaire, Relative Constant Murley score (RCMS) and underwent range of motion and strength assessment. RESULTS: Data of 134 patients who had surgery from April 2001 to July 2011 were used for analysis. One hundred and eight patients underwent TSA (81%) and 26 (19%) had HHR. Both surgeries were associated with a statistically significant improvement in physical symptoms, ASES, RCMS, range of motion and strength (p <0.0001). The greatest change for all outcomes occurred within the first 6-months of surgery. Improvement in ASES, RCMS continued up to 12-months and then plateaued. Improvement in physical symptoms leveled off at 6-months in the HHR group but continued up to 12-months in the TSR group. Strength showed improvement in both groups up to 24-months post-surgery. CONCLUSION: Both TSA and HHR groups showed a statistically significant improvement in perceived disability, range of motion and strength over two years with the greatest improvement made by 6 months. The recovery profiles for the surgeries showed different patterns. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2474-15-306) contains supplementary material, which is available to authorized users

The Fit-HaNSA Demonstrates Reliability and Convergent Validity of Functional Performance in Patients with Shoulder Disorders

Study DesignPsychometric study design. Objectives To assess the test-retest reliability and convergent validity of the Functional Impairment Test-Hand and Neck/Shoulder/Arm (FIT-HaNSA) in patients with shoulder disorders. Background Performance tests that assess functional ability of patients with shoulder disorders can provide useful information for making clinical or return-to-activity decisions. No performance-based shoulder test has yet demonstrated sufficient relevance or clinical measurement properties. The FIT-HaNSA examines upper extremity performance during repetitive tasks that emphasize shoulder reaching and static postures and, therefore, has greater relevance for assessing performance. Methods Thirty-six patients with shoulder disorders and 65 healthy controls were recruited for the study. The FIT-HaNSA, the Disabilities of the Arm, Shoulder and Hand questionnaire, the Shoulder Pain and Disability Index, isometric shoulder strength, and shoulder range of motion were assessed at baseline and repeated 2 to 7 days later. Test-retest reliability was described using intraclass correlation coefficient (ICC2,1) and standard error of measurement. Pearson correlation coefficients were used to examine the level of association between the FIT-HaNSA scores and the other measures. Results The ICCs for test-retest reliability for the FIT-HaNSA ranged from 0.89 to 0.97 in the patient group and 0.79 to 0.91 in the control group. The FIT-HaNSA showed high correlation with the Disabilities of the Arm, Shoulder and Hand and the Shoulder Pain and Disability Index, and moderate correlations with shoulder range of motion and muscle strength. Conclusion The FIT-HaNSA demonstrated high test-retest reliability and convergent validity with other related outcomes in patients with shoulder disorders. Further longitudinal studies are required to evaluate the responsiveness of the FIT-HaNSA in patients with different upper extremity conditions. J Orthop Sports Phys Ther 2012;42(5):455–464, Epub 25 January 2012. doi:10.2519/jospt.2012.379

Measurement Based Resource Allocation for Multimedia Applications

Modern networks are now capable of guaranteeing a consistent Quality of Service (QoS) to multimedia traffic streams. A number of major operating system vendors are also working hard to extend these guarantees into the end-system. In both cases, however, there remains the problem of determining a service rate sufficient to ensure the desired Quality of Service. Source modelling is not a sustainable approach in the network case and it is even less feasible to model the demands of multimedia applications. The ESPRIT Measure project is successfully using online measurement and estimation to perform resource allocation for bursty traffic in ATM networks. In this paper we consider the applicability of the same theory to resource allocation in a multimedia operating system which offers QoS guarantees to its applications

Optimizing Reliability of Digital Inclinometer and Flexicurve Ruler Measures of Spine Curvatures in Postmenopausal Women with Osteoporosis of the Spine: An Illustration of the Use of Generalizability Theory

The study illustrates the application of generalizability theory (G-theory) to identify measurement protocols that optimize reliability of two clinical methods for assessing spine curvatures in women with osteoporosis. Triplicate measures of spine curvatures were acquired for 9 postmenopausal women with spine osteoporosis by two raters during a single visit using a digital inclinometer and a flexicurve ruler. G-coefficients were estimated using a G-study, and a measurement protocol that optimized inter-rater and inter-trial reliability was identified using follow-up decision studies. The G-theory provides reliability estimates for measurement devices which can be generalized to different clinical contexts and/or measurement designs

Demixing, remixing and cellular networks in binary liquids containing colloidal particles

We present a confocal-microscopy study of demixing and remixing in binary liquids containing colloidal particles. First, particle-stabilized emulsions have been fabricated by nucleation and growth of droplets upon cooling from the single-fluid phase. We show that their stability mainly derives from interfacial particles; the surplus of colloids in the continuous phase possibly provides additional stability. Upon heating these emulsions, we have observed the formation of polyhedral cellular networks of colloids, just before the system remixes. Given a suitable liquid-liquid composition, the initial emulsions cross the binary-liquid symmetry line due to creaming. Therefore, upon heating, the droplets do not shrink and they remain closely packed. The subsequent network formation relies on a delicate balance between the Laplace pressure and the pressure due to creaming/remixing. As high concentrations of colloids in the cell walls inhibit film thinning and rupture, the networks can be stabilized for more than 30 minutes. This opens up an avenue for their application in the fabrication of advanced materials.Comment: http://dx.doi.org/10.1039/b918002

Characterizing the recovery trajectories of knee range of motion for one year after total knee replacement

DESIGN: Retrospective analysis of routinely collected clinical data. OBJECTIVE: This study modeled the recovery in knee flexion and extension range of motion (ROM) over 1 year after total knee replacement (TKR). BACKGROUND: Recovery after TKR has been characterized for self-reported pain and functional status. Literature describing target knee ROM at different follow-up periods after TKR is scarce. METHODS: Data were extracted for patients who had undergone TKR at a tertiary care hospital at 2, 8, 12, 26, and 52 weeks after TKR. A linear mixed-effects growth model was constructed that investigated the following covariates age, sex, pre-TKR range, body mass index, duration of symptoms, and their interaction with weeks post TKR. RESULTS: Of the 559 patients included (age 64.8 ± 8.5 years), 370 were women and 189 were men. Knee ROM showed the greatest change during the first 12 weeks after TKR, plateauing by 26 weeks. For an average patient, knee flexion increased from approximately 100º 2 weeks post TKR to 117º 52 weeks post TKR. Knee extension increased from approximately 3º knee flexion 2 weeks post TKR to 1º flexion 52 weeks post TKR. CONCLUSIONS: The results showed that the maximum gains in knee ROM should be expected within the first 12 weeks with small changes occurring up to 26 weeks after TKR. In addition, age and presurgery knee ROM are associated with the gains in knee ROM and should be factored into the estimation of expected knee ROM at a given follow-up interval after TKR