The measurement of lubricant-film thickness using ultrasound

Ultrasound is reflected from a liquid layer between two solid bodies. This reflection depends on the ultrasonic frequency, the acoustic properties of the liquid and solid, and the layer thickness. If the wavelength is much greater than the liquid-layer thickness, then the response is governed by the stiffness of the layer. If the wavelength and layer thickness are similar, then the interaction of ultrasound with the layer is controlled by its resonant behaviour. This stiffness governed response and resonant response can be used to determine the thickness of the liquid layer, if the other parameters are known. In this paper, ultrasound has been developed as a method to determine the thickness of lubricating films in bearing systems. An ultrasonic transducer is positioned on the outside of a bearing shell such that the wave is focused on the lubricant-film layer. The transducer is used to both emit and receive wide-band ultrasonic pulses. For a particular lubricant film, the reflected pulse is processed to give a reflection-coefficient spectrum. The lubricant-film thickness is then obtained from either the layer stiffness or the resonant frequency. The method has been validated using fluid wedges at ambient pressure between flat and curved surfaces. Experiments on the elastohydrodynamic film formed between a sliding ball and a flat surface were performed. Film-thickness values in the range 50-500 nm were recorded, which agreed well with theoretical film-formation predictions. Similar measurements have been made on the oil film between the balls and outer raceway of a deep-groove ball bearing

Gastrostomies Preserve but do not Increase Quality of Life for Patients and Caregivers

BACKGROUND & AIMS: Gastrostomies are widely used to provide long-term enteral nutrition to patients with neurological conditions that affect swallowing (such as following a cerebrovascular accident or for patients with motor neuron disease) or with oropharyngeal malignancies. The benefits derived from this intervention are uncertain for patients and caregivers. We conducted a prospective, multicenter cohort study to determine how gastrostomies affect health-related quality of life (HRQoL) in recipients and caregivers. METHODS: We performed a study of 100 patients who received gastrostomies (55% percutaneous endoscopic gastrostomy, 45% radiologically inserted) at 5 centers in the United Kingdom, 100 caregivers, and 200 population controls. We used the EuroQol-5D (EQ-5D, comprising a questionnaire, index, visual analogue scale) to assess HRQoL for patients and caregivers before the gastrostomy insertion and then 3 months afterward; findings were compared with those from controls. Ten patients and 10 caregivers were also interviewed after the procedure to explore quantitative findings. Findings from the EQ-5D and semi-structured interviews were integrated using a mixed methods matrix. RESULTS: Six patients died before the 3-month HRQoL reassessments. We observed no significant longitudinal changes in mean EQ-5D index scores for patients (0.70 before vs 0.710 after; P=.83) or caregivers (0.95 before vs 0.95 after; P=.32) following gastrostomy insertion. The semi-structured interviews revealed problems in managing gastrostomy tubes, social isolation, and psychological and emotional consequences that reduced HRQoL. CONCLUSIONS: We performed a mixed methods prospective study of the effects of gastrostomy feeding on HRQoL. HRQoL did not significantly improve after gastrostomy insertion for patients or caregivers. The lack of significant decrease in HRQoL after the procedure indicates that gastrostomies may help maintain HRQoL. Findings have relevance to those involved in gastrostomy insertion decisions and indicate the importance of carefully selecting patients for this intervention, despite the relative ease of insertion

Auto-calibration of ultrasonic lubricant-film thickness measurements

The measurement of oil film thickness in a lubricated component is essential information for performance monitoring and design. It is well established that such measurements can be made ultrasonically if the lubricant film is modelled as a collection of small springs. The ultrasonic method requires that component faces are separated and a reference reflection recorded in order to obtain a reflection coefficient value from which film thickness is calculated. The novel and practically useful approach put forward in this paper and validated experimentally allows reflection coefficient measurement without the requirement for a reference. This involves simultaneously measuring the amplitude and phase of an ultrasonic pulse reflected from a layer. Provided that the acoustic properties of the substrate are known, the theoretical relationship between the two can be fitted to the data in order to yield reflection coefficient amplitude and phase for an infinitely thick layer. This is equivalent to measuring a reference signal directly, but importantly does not require the materials to be separated. The further valuable aspect of this approach, which is demonstrated experimentally, is its ability to be used as a self-calibrating routine, inherently compensating for temperature effects. This is due to the relationship between the amplitude and phase being unaffected by changes in temperature which cause unwanted changes to the incident pulse. Finally, error analysis is performed showing how the accuracy of the results can be optimized. A finding of particular significance is the strong dependence of the accuracy of the technique on the amplitude of reflection coefficient input data used. This places some limitations on the applicability of the technique. © 2008 IOP Publishing Ltd

Cisplatin-induced emesis: systematic review and meta-analysis of the ferret model and the effects of 5-HT3 receptor antagonists

PURPOSE: The ferret cisplatin emesis model has been used for ~30 years and enabled identification of clinically used anti-emetics. We provide an objective assessment of this model including efficacy of 5-HT(3) receptor antagonists to assess its translational validity. METHODS: A systematic review identified available evidence and was used to perform meta-analyses. RESULTS: Of 182 potentially relevant publications, 115 reported cisplatin-induced emesis in ferrets and 68 were included in the analysis. The majority (n = 53) used a 10 mg kg(−1) dose to induce acute emesis, which peaked after 2 h. More recent studies (n = 11) also used 5 mg kg(−1), which induced a biphasic response peaking at 12 h and 48 h. Overall, 5-HT(3) receptor antagonists reduced cisplatin (5 mg kg(−1)) emesis by 68% (45–91%) during the acute phase (day 1) and by 67% (48–86%) and 53% (38–68%, all P < 0.001), during the delayed phase (days 2, 3). In an analysis focused on the acute phase, the efficacy of ondansetron was dependent on the dosage and observation period but not on the dose of cisplatin. CONCLUSION: Our analysis enabled novel findings to be extracted from the literature including factors which may impact on the applicability of preclinical results to humans. It reveals that the efficacy of ondansetron is similar against low and high doses of cisplatin. Additionally, we showed that 5-HT(3) receptor antagonists have a similar efficacy during acute and delayed emesis, which provides a novel insight into the pharmacology of delayed emesis in the ferret

The PNL high-transmission three-stage mass spectrometer

We have constructed a three-stage isotope-ratio mass spectrometer of unique ion-optical design that achieves high ion transmission efficiency and high abundance sensitivity. The spectrometer has tandem 90[degrees] -deflection magnets with boundaries 18[degrees] off normal. The magnet drift lengths are 1.48 times the 27-cm radius of deflection. This extended geometry gives mass dispersion equivalent to a 40-cm-radius magnet with normal boundaries. The first magnet renders the ion beam parallel in the vertical plane and provides a focus in the horizontal plane of mass dispersion. The second magnet brings the beam to a stigmatic focus. This novel ion-optical design gives 100% transmission without the need for intermediate focusing lenses. It also provides a 16% increase in mass resolution over the traditional tandem geometry with normal magnet boundaries. Complete transmission of ions is maintained through a third-stage cylindrical electric sector of 38-cm radius, which provides increased isotope-abundance sensitivity. The isotope-abundance sensitivity of the new mass spectrometer is an order of magnitude better than similar instruments with normal magnet boundaries. This is because the vertical focusing of the ion beam prevents ion scattering from the top and bottom of the flight tube. The measured values of the isotope-abundance sensitivity one-half mass unit away from the rhenium ion peaks at masses 185 and 187 are M [minus] 1/2 = (6.5 [plus minus] 0.5)[times] 0[sup [minus]10] M + 1/2 = (3.1 [plus minus] 0.8) [times] 10[sup [minus]10]. By extrapolation, the uranium isotope-abundance sensitivity is m [minus] 1 = 1 [times] 10[sup [minus]10]. Construction of the instrument was facilitated by using standard commercial mass spectrometer components

Momentum asymmetries as CP violating observables

Three body decays can exhibit CP violation that arises from interfering diagrams with different orderings of the final state particles. We construct several momentum asymmetry observables that are accessible in a hadron collider environment where some of the final state particles are not reconstructed and not all the kinematic information can be extracted. We discuss the complications that arise from the different possible production mechanisms of the decaying particle. Examples involving heavy neutralino decays in supersymmetric theories and heavy Majorana neutrino decays in Type-I seesaw models are examined.Comment: 20 pages, 9 figures. Clarifying comments and one reference added, matches published versio

Teacher unionism in changing times: is this the real “new unionism”?

This article provides a case study of union change in an environment in which radical school restructuring is taking place, and active strategies to weaken and marginalize organized teachers are being pursued by the state. The case study union is the National Union of Teachers in England. The article explores a number of different strategies open to teacher unions, utilizing a framework provided by Turner (2004). Drawing on data collected at a national level, and in three local authority areas, I argue that the National Union of Teachers’ response to the erosion of collective bargaining is best presented as an amalgam of strategies focused on workplace organizing, political campaigning, and coalition building. The data demonstrate considerable congruence between national and local strategies, although local data reveal considerable challenges in implementation and consequently considerable unevenness in local experiences

Urinary C-Peptide Creatinine Ratio Is a Practical Outpatient Tool for Identifying Hepatocyte Nuclear Factor 1-α/Hepatocyte Nuclear Factor 4-α Maturity-Onset Diabetes of the Young From Long-Duration Type 1 Diabetes

Hepatocyte nuclear factor 1-α (HNF1A)/hepatocyte nuclear factor 4-α (HNF4A) maturity-onset diabetes of the young (MODY) is frequently misdiagnosed as type 1 diabetes, and patients are inappropriately treated with insulin. Blood C-peptide can aid in the diagnosis of MODY, but practical reasons limit its widespread use. Urinary C-peptide creatinine ratio (UCPCR), a stable measure of endogenous insulin secretion, is a noninvasive alternative. We aimed to compare stimulated UCPCR in adults with HNF1A/4A MODY, type 1 diabetes, and type 2 diabetes.RD&E staff can access the full-text of this article via OpenAthens. Click on the 'Additional Link' above to access the full-text and log in with NHS OpenAthens if prompted.PDA/02/06/098/Department of Health/United Kingdo