A spin- and angle-resolving photoelectron spectrometer

A new type of hemispherical electron energy analyzer that permits angle and spin resolved photoelectron spectroscopy has been developed. The analyzer permits standard angle resolved spectra to be recorded with a two-dimensional detector in parallel with spin detection using a mini-Mott polarimeter. General design considerations as well as technical solutions are discussed and test results from the Au(111) surface state are presented

A forage-only diet alters the metabolic response of horses in training

Most athletic horses are fed a high-starch diet despite the risk of health problems. Replacing starch concentrate with high-energy forage would alleviate these health problems, but could result in a shift in major substrates for muscle energy supply from glucose to short-chain fatty acids (SCFA) due to more hindgut fermentation of fibre. Dietary fat inclusion has previously been shown to promote aerobic energy supply during exercise, but the contribution of SCFA to exercise metabolism has received little attention. This study compared metabolic response with exercise and lactate threshold (VLa4) in horses fed a forage-only diet (F) and a more traditional high-starch, low-energy forage diet (forage–concentrate diet - FC). The hypothesis was that diet F would increase plasma acetate concentration and increase VLa4 compared with diet FC. Six Standardbred geldings in race training were used in a 29-day change-over experiment. Plasma acetate, non-esterified fatty acids (NEFA), lactate, glucose and insulin concentrations and venous pH were measured in samples collected before, during and after a treadmill exercise test (ET, day 25) and muscle glycogen concentrations before and after ET. Plasma acetate concentration was higher before and after exercise in horses on diet F compared with diet FC, and there was a tendency ( P50.09) for increased VLa4 on diet F. Venous pH and plasma glucose concentrations during exercise were higher in horses on diet F than diet FC, as was plasma NEFA on the day after ET. Plasma insulin and muscle glycogen concentrations were lower for diet F, but glycogen utilisation was similar for the two diets. The results show that a high-energy, forage-only diet alters the metabolic response to exercise and, with the exception of lowered glycogen stores, appears to have positive rather than negative effects on performance traits

Isolation of native plasma membrane H⁺-ATPase (Pma1p) in both the active and basal activation states

The yeast plasma membrane H(+)-ATPase Pma1p is a P-type ATPase that energizes the yeast plasma membrane. Pma1p exists in two activation states: an autoinhibited basal state and an activated state. Here we show that functional and stable Pma1p can be purified in native form and reconstituted in artificial liposomes without altering its activation state. Acetylated tubulin has previously been reported to maintain Pma1p in the basal state but, as this protein was absent from the purified preparations, it cannot be an essential component of the autoinhibitory mechanism. Purification of and reconstitution of native Pma1p in both activation states opens up for a direct comparison of the transport properties of these states, which allowed us to confirm that the basal state has a low coupling ratio between ATP hydrolysis and protons pumped, whereas the activated state has a high coupling ratio. The ability to prepare native Pma1p in both activation states will facilitate further structural and biochemical studies examining the mechanism by which plasma membrane H(+)-ATPases are autoinhibited

Cumulative fatigue damage of stress below the fatigue limit in weldment steel under block loading

To investigate the cumulative fatigue damage below the fatigue limit of multipass weldment martensitic stainless steel, and to clarify the effect of cycle ratios and high‐stress level in the statement, fatigue tests were conducted under constant and combined high‐ and low‐stress amplitude relative to stress above and below the fatigue limit. The outcomes indicate that neither modified Miner's nor Haibach's approach provided accurate evaluation under repeated two‐step amplitude loading. Moreover, effect of cycle ratios has been determined. Additionally, the cumulative fatigue damage saturated model is established and validated. Cumulative fatigue damage contributed by low‐stress below the fatigue limit in high stress of 700 MPa is higher than that with 650 MPa at identical conditions (fatigue limit 575 MPa). Thus, high stress affects fatigue damage behaviour below the fatigue limit. A new predicted approach has been proposed based on Corten‐Dolan law, whose accuracy and applicability have been proven

Direct load monitoring of rolling bearing contacts using ultrasonic time of flight

The load applied by each rolling element on a bearing raceway controls friction, wear and service life. It is possible to infer bearing load from load cells or strain gauges on the shaft or bearing housing. However, this is not always simply and uniquely related to the real load transmitted by rolling elements directly to the raceway. Firstly, the load sharing between rolling elements in the raceway is statically indeterminate, and secondly, in a machine with non-steady loading, the load path is complex and highly transient being subject to the dynamic behaviour of the transmission system. This study describes a method to measure the load transmitted directly by a rolling element to the raceway by using the time of flight (ToF) of a reflected ultrasonic pulse. A piezoelectric sensor was permanently bonded onto the bore surface of the inner raceway of a cylindrical roller bearing. The ToF of an ultrasonic pulse from the sensor to the roller-raceway contact was measured. This ToF depends on the speed of the wave and the thickness of the raceway. The speed of an ultrasonic wave changes with the state of the stress, known as the acoustoelastic effect. The thickness of the material varies when deflection occurs as the contacting surfaces are subjected to load. In addition, the contact stiffness changes the phase of the reflected signal and in simple peak-to-peak measurement, this appears as a change in the ToF. In this work, the Hilbert transform was used to remove this contact dependent phase shift. Experiments have been performed on both a model line contact and a single row cylindrical roller bearing from the planet gear of a wind turbine epicyclic gearbox. The change in ToF under different bearing loads was recorded and used to determine the deflection of the raceway. This was then related to the bearing load using a simple elastic contact model. Measured load from the ultrasonic reflection was compared with the applied bearing load with good agreement. The technique shows promise as an effective method for load monitoring in real-world bearing applications

Fixed Effect Estimation of Large T Panel Data Models

This article reviews recent advances in fixed effect estimation of panel data models for long panels, where the number of time periods is relatively large. We focus on semiparametric models with unobserved individual and time effects, where the distribution of the outcome variable conditional on covariates and unobserved effects is specified parametrically, while the distribution of the unobserved effects is left unrestricted. Compared to existing reviews on long panels (Arellano and Hahn 2007; a section in Arellano and Bonhomme 2011) we discuss models with both individual and time effects, split-panel Jackknife bias corrections, unbalanced panels, distribution and quantile effects, and other extensions. Understanding and correcting the incidental parameter bias caused by the estimation of many fixed effects is our main focus, and the unifying theme is that the order of this bias is given by the simple formula p/n for all models discussed, with p the number of estimated parameters and n the total sample size.Comment: 40 pages, 1 tabl

Skills, attitudes and uptake of evidence-based practice: a cross-sectional study of chiropractors in the Swedish Chiropractic Association.

BackgroundEvidence-based practice (EBP) is integral to the delivery of high-quality health care. Chiropractic has been a licensed health profession in Sweden since 1989, but little is known of the uptake of EBP in this professional group. This study explored the self-reported skills, attitudes and uptake of EBP, and the enablers and barriers of EBP uptake, among licensed chiropractors in Sweden.MethodsLicensed chiropractors (n = 172) of the Swedish Chiropractic Association (Legitimerade Kiropraktorers Riksorganisation) were invited to participate in an anonymous online questionnaire, using the Evidence-Based Practice Attitude and Utilisation Survey (EBASE) in February 2019.ResultsFifty-six (33%) chiropractors completed the survey. Participants were predominantly male, aged 30-49 years, held a Master's degree, and had received their highest qualification and practiced chiropractic for over a decade. Chiropractors rated their EBP skill-level mostly in the moderate to moderate-high range. The majority of chiropractors reported positive attitudes towards EBP, with most agreeing or strongly agreeing that EBP is necessary in the practice of chiropractic, and that EBP assists in making decisions about patient care. Chiropractors reported an average level of engagement in EBP activities. All participants indicated professional literature and research findings were useful in their day-to-day chiropractic practice. The main perceived enabler of EBP uptake was internet access in the workplace, whereas the main barrier to EBP uptake was lack of clinical evidence in chiropractic.ConclusionsParticipating chiropractors of the Swedish Chiropractic Association were generally favourable of EBP, though only reported modest levels of EBP-related skills and engagement in EBP activities. Our findings suggest future studies investigating interventions focussed on improving chiropractors' skills and uptake of EBP are warranted

Investigating in-service failures of water pipes from a multiaxial notch fatigue point of view: A conceptual study

Many mechanisms and processes can cause deterioration and ultimately failure of water distribution pipes during in-service operation, amongst these is damage caused by metal fatigue. This paper summarises an attempt at formalising a novel methodology suitable for estimating the number of years taken for a through thickness fatigue crack to form in this complex scenario. The devised method is based on the so-called modified Wo¨hler curve method and can be applied to estimate fatigue damage of water pipes independently from the degree of multiaxiality and non-proportionality of the load history. The computational approach of the proposed fatigue life estimation technique makes full use of an incremental procedure: fatigue damage is evaluated year by year by assuming that all variable involved in the process can change over time. The detrimental effect of corrosion pits is directly accounted for by treating them as conventional notches whose size increases with time. Finally, by taking as reference information the number of years for a blowout hole to form, the proposed approach is used to show how the lifetime of grey cast iron pipes can be remarkably shortened by fatigue