First Measurement of the Nuclear-Recoil Ionization Yield in Silicon at 100 eV

We measured the nuclear-recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a monoenergetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4 keV down to 100 eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100 eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale.

Neutron emission spectrometer to measure ion temperature on the Fusion Demonstration Plant

General Fusion is building the Fusion Demonstration Plant to demonstrate a magnetized target fusion scheme in which a deuterium plasma is heated from 200 eV to 10 keV by piston-driven compression of a liquid-lithium liner. The multilayer coaxial time-of-flight neutron emission spectrometer is designed to measure the ion temperature near peak compression at which time the neutron yield will approach 10¹⁸ neutrons/s. The neutron energy distribution is expected to be Gaussian since the machine uses no neutral beam or radio-frequency heating. In this case, analysis shows that as few as 500 coincidence events should be sufficient to accurately measure the ion temperature. This enables a fast time resolution of 10 µs, which is required to track the rapid change in temperature approaching peak compression. We overcome the challenges of neutron pile-up and event ambiguity with a compact design having two layers of segmented scintillators. The error in the ion temperature measurement is computed as a function of the neutron spectrometer's geometric parameters and used to optimize the design for the case of reaching 10 keV at peak compression.

Constraints on Lightly Ionizing Particles from CDMSlite

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to lightly ionizing particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically produced LIPs with an electric charge smaller than e/(3×10^{5}), as well as the strongest limits for charge ≤e/160, with a minimum vertical intensity of 1.36×10^{-7}  cm^{-2} s^{-1} sr^{-1} at charge e/160. These results apply over a wide range of LIP masses (5  MeV/c^{2} to 100  TeV/c^{2}) and cover a wide range of βγ values (0.1-10^{6}), thus excluding nonrelativistic LIPs with βγ as small as 0.1 for the first time.

Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated above Ground

We present limits on spin-independent dark matter-nucleon interactions using a 10.6 g Si athermal phonon detector with a baseline energy resolution of σ_{E}=3.86±0.04(stat)_{-0.00}^{+0.19}(syst)  eV. This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from 93 to 140  MeV/c^{2}, with a raw exposure of 9.9 g d acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.

Phase analysis, a novel SPECT technique for left ventricular dyssynchrony: Are degrees and milliseconds interchangeable?

BACKGROUND

Phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy provides a measure of left ventricular dyssynchrony and may have applications for identifying patients suitable for cardiac resynchronisation therapy. Phase analysis is typically described in degrees of cardiac cycle, less intuitive to cardiologists familiar with ECGs. We assessed the relationship between time and degrees, to determine whether they are interchangeable.

METHODS AND RESULTS

399 patients underwent normal stress-only SPECT myocardial perfusion imaging using Technetium-99m-tetrofosmin. Data analysis used QGS software (Cedars Sinai) calculating bandwidth and standard deviation. Heart rate, age, gender, stress modality, and ejection fraction were analyzed for their relation to phase variables. 13 patients were excluded for conduction abnormalities including right and left bundle branch block and ventricular pacing. Heart rate was strongly correlated to bandwidth and standard deviation measured in time, but unrelated when measured in degrees. Although bandwidth measured by time and degrees were strongly correlated with each other this relationship was not perfect (correlation coefficient 0.87, P < .001). The addition of heart rate to the model explained most of the residual variation between the two. The results for standard deviation were similar.

CONCLUSION

In patients with normal myocardial perfusion and QRS duration bandwidth measured by degrees is not directly interchangeable with time in milliseconds. However most of the variation is explainable by heart rate, which predominantly affects measures of time rather than degrees. We would propose that although the values are less intuitive to cardiologists, normal ranges for phase measured in degrees are potentially more robust.

Erratum: First Dark Matter Constraints from a SuperCDMS Single-Charge Sensitive Detector [Phys. Rev. Lett. 121, 051301 (2018)]

This corrects the article DOI: 10.1103/PhysRevLett.121.051301.

First Dark Matter Constraints from a SuperCDMS Single-Charge Sensitive Detector

We present the first limits on inelastic electron-scattering dark matter and dark photon absorption using a prototype SuperCDMS detector having a charge resolution of 0.1 electron-hole pairs (CDMS HVeV, a 0.93 g CDMS high-voltage device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1  MeV/c^{2}. We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 g d). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.

Results from the Super Cryogenic Dark Matter Search Experiment at Soudan

We report the result of a blinded search for weakly interacting massive particles (WIMPs) using the majority of the SuperCDMS Soudan data set. With an exposure of 1690 kg d, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP-nucleon cross section of 1.4×10^{-44} (1.0×10^{-44})  cm^{2} at 46  GeV/c^{2}. These results set the strongest limits for WIMP-germanium-nucleus interactions for masses >12  GeV/c^{2}.

The Boltzmann project

The International Committee for Weights and Measures (CIPM), at its meeting in October 2017, followed the recommendation of the Consultative Committee for Units (CCU) on the redefinition of the kilogram, ampere, kelvin and mole. For the redefinition of the kelvin, the Boltzmann constant will be fixed with the numerical value 1.380 649 × 10-23 J K-1. The relative standard uncertainty to be transferred to the thermodynamic temperature value of the triple point of water will be 3.7 × 10-7, corresponding to an uncertainty in temperature of 0.10 mK, sufficiently low for all practical purposes. With the redefinition of the kelvin, the broad research activities of the temperature community on the determination of the Boltzmann constant have been very successfully completed. In the following, a review of the determinations of the Boltzmann constant k, important for the new definition of the kelvin and performed in the last decade, is given.

Multimodality imaging evaluation of Chagas disease: an expert consensus of Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI)

Aims

To develop a document by Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI) to review and summarize the most recent evidences about the non-invasive assessment of patients with Chagas disease, with the intent to set up a framework for standardized cardiovascular imaging to assess cardiovascular morphologic and functional disturbances, as well as to guide the subsequent process of clinical decision-making.

Methods and results

Chagas disease remains one of the most prevalent infectious diseases in Latin America, and has become a health problem in non-endemic countries. Dilated cardiomyopathy is the most severe manifestation of Chagas disease, which causes substantial disability and early mortality in the socially most productive population leading to a significant economical burden. Prompt and correct diagnosis of Chagas disease requires specialized clinical expertise to recognize the unique features of this disease. The appropriate and efficient use of cardiac imaging is pivotal for diagnosing the cardiac involvement in Chagas disease, to stage the disease, assess patients' prognosis and address management. Echocardiography is the most common imaging modality used to assess, and follow-up patients with Chagas disease. The presence of echocardiographic abnormalities is of utmost importance, since it allows to stage patients according to disease progression. In early stages of cardiac involvement, echocardiography may demonstrate segmental left ventricuar wall motion abnormalities, mainly in the basal segments of inferior, inferolateral walls, and the apex, which cannot be attributed to obstructive coronary artery arteries. The prevalence of segmental wall motion abnormalities varies according to the stage of the disease, reaching about 50% in patients with left ventricular dilatation and dysfunction. Speckle tracking echocardiography allows a more precise and quantitative measurement of the regional myocardial function. Since segmental wall motion abnormalities are frequent in Chagas disease, speckle tracking echocardiography may have an important clinical application in these patients, particularly in the indeterminate forms when abnormalities are more subtle. Speckle tracking echocardiography can also quantify the heterogeneity of systolic contraction, which is associated with the risk of arrhythmic events. Three-dimensional (3D) echocardiography is superior to conventional two-dimensional (2D) echocardiography for assessing more accurately the left ventricular apex and thus to detect apical aneurysms and thrombus in patients in whom ventricular foreshortening is suspected by 2D echocardiography. In addition, 3D echocardiography is more accurate than 2D Simpson s biplane rule for assessing left ventricular volumes and function in patients with significant wall motion abnormalities, including aneurysms with distorted ventricular geometry. Contrast echocardiography has the advantage to enhancement of left ventricular endocardial border, allowing for more accurate detection of ventricular aneurysms and thrombus in Chagas disease. Diastolic dysfunction is an important hallmark of Chagas disease even in its early phases. In general, left ventricular diastolic and systolic dysfunction coexist and isolated diastolic dysfunction is uncommon but may be present in patients with the indeterminate form. Right ventricular dysfunction may be detected early in the disease course, but in general, the clinical manifestations occur late at advanced stages of Chagas cardiomyopathy. Several echocardiographic parameters have been used to assess right ventricular function in Chagas disease, including qualitative evaluation, myocardial performance index, tissue Doppler imaging, tricuspid annular plane systolic excursion, and speckle tracking strain. Cardiac magnetic resonance (CMR) is useful to assess global and regional left ventricular function in patients with Chagas diseases. Myocardial fibrosis is a striking feature of Chagas cardiomyopathy and late gadolinium enhancement (LGE) is used to detect and quantify the extension of myocardial fibrosis. Myocardial fibrosis might have a role in risk stratification of patients with Chagas disease. Limited data are available regarding right ventricular function assessed by CMR in Chagas disease. Radionuclide ventriculography is used for global biventricular function assessment in patients with suspected or definite cardiac involvement in Chagas disease with suboptimal acoustic window and contraindication to CMR. Myocardial perfusion scintigraphy may improve risk stratification to define cardiac involvement in Chagas disease, especially in the patients with devices who cannot be submitted to CMR and in the clinical setting of Chagas patients whose main complaint is atypical chest pain. Detection of reversible ischemic defects predicts further deterioration of left ventricular systolic function and helps to avoid unnecessary cardiac catheterization and coronary angiography.

Conclusion

Cardiac imaging is crucial to detect the cardiac involvement in patients with Chagas disease, stage the disease and stratify patient risk and address management. Unfortunately, most patients live in regions with limited access to imaging methods and point-of-care, simplified protocols, could improve the access of these remote populations to important information that could impact in the clinical management of the disease. Therefore, there are many fields for further research in cardiac imaging in Chagas disease. How to better provide an earlier diagnosis of cardiac involvement and improve patients risk stratification remains to be addressed using different images modalities.

The paradoxical psychological effects of lysergic acid diethylamide (LSD)

BACKGROUND

Lysergic acid diethylamide (LSD) is a potent serotonergic hallucinogen or psychedelic that modulates consciousness in a marked and novel way. This study sought to examine the acute and mid-term psychological effects of LSD in a controlled study.

METHOD

A total of 20 healthy volunteers participated in this within-subjects study. Participants received LSD (75 µg, intravenously) on one occasion and placebo (saline, intravenously) on another, in a balanced order, with at least 2 weeks separating sessions. Acute subjective effects were measured using the Altered States of Consciousness questionnaire and the Psychotomimetic States Inventory (PSI). A measure of optimism (the Revised Life Orientation Test), the Revised NEO Personality Inventory, and the Peter's Delusions Inventory were issued at baseline and 2 weeks after each session.

RESULTS

LSD produced robust psychological effects; including heightened mood but also high scores on the PSI, an index of psychosis-like symptoms. Increased optimism and trait openness were observed 2 weeks after LSD (and not placebo) and there were no changes in delusional thinking.

CONCLUSIONS

The present findings reinforce the view that psychedelics elicit psychosis-like symptoms acutely yet improve psychological wellbeing in the mid to long term. It is proposed that acute alterations in mood are secondary to a more fundamental modulation in the quality of cognition, and that increased cognitive flexibility subsequent to serotonin 2A receptor (5-HT2AR) stimulation promotes emotional lability during intoxication and leaves a residue of 'loosened cognition' in the mid to long term that is conducive to improved psychological wellbeing.

Appraisals of psychotic experiences: an experimental investigation of symptomatic, remitted and non-need-for-care individuals

BACKGROUND

Appraisals are suggested to play a determining role in the clinical outcome of psychotic experiences (PEs). We used experimental tasks that mimic PEs to investigate appraisals in individuals with PEs with and without a 'need-for-clinical-care', and psychosis patients whose symptoms have remitted. We predicted that patients would appraise the tasks as threatening regardless of current symptom level, while non-clinical and control groups would appraise them as non-threatening.

METHOD

Appraisals following three anomalous experiences-inducing tasks [Telepath, Cards task, Virtual acoustic space paradigm (VASP)] were examined in 71 individuals: symptomatic (n = 18) and remitted (n = 16) psychosis patients; non-clinical group with PEs (n = 16); controls without PEs (n = 21).

RESULTS

As predicted, symptomatic patients endorsed more threatening appraisals for all tasks than non-clinical and control groups, who did not differ from each other. However, remitted patients were less likely to endorse threatening appraisals of the Cards and Telepath than their symptomatic counterparts, although they did not differ in global ratings of how striking, threatening and distressing they found the tasks. Moreover, remitted participants endorsed more threatening appraisals of the Telepath and VASP than non-clinical participants, and of the VASP than controls. Remitted participants also rated all three tasks as globally more threatening than the non-clinical group and controls.

CONCLUSIONS

Clinical outcome may not necessarily be driven by the presence of symptoms, with threatening appraisals of PEs representing a key factor. The remitted group's intermediate appraisal scores imply that the relationship between appraisal and clinical outcome is not straightforward, and potential mediating factors need to be determined.

Estimates of the difference between thermodynamic temperature and the International Temperature Scale of 1990 in the range 118 K to 303 K

Using exceptionally accurate measurements of the speed of sound in argon, we have made estimates of the difference between thermodynamic temperature, T, and the temperature estimated using the International Temperature Scale of 1990, T90, in the range 118 K to 303 K. Thermodynamic temperature was estimated using the technique of relative primary acoustic thermometry in the NPL-Cranfield combined microwave and acoustic resonator. Our values of (T-T90) agree well with most recent estimates, but because we have taken data at closely spaced temperature intervals, the data reveal previously unseen detail. Most strikingly, we see undulations in (T-T90) below 273.16 K, and the discontinuity in the slope of (T-T90) at 273.16 K appears to have the opposite sign to that previously reported.

New Results from the Search for Low-Mass Weakly Interacting Massive Particles with the CDMS Low Ionization Threshold Experiment

The CDMS low ionization threshold experiment (CDMSlite) uses cryogenic germanium detectors operated at a relatively high bias voltage to amplify the phonon signal in the search for weakly interacting massive particles (WIMPs). Results are presented from the second CDMSlite run with an exposure of 70 kg day, which reached an energy threshold for electron recoils as low as 56 eV. A fiducialization cut reduces backgrounds below those previously reported by CDMSlite. New parameter space for the WIMP-nucleon spin-independent cross section is excluded for WIMP masses between 1.6 and 5.5  GeV/c^{2}.

Sarcoidosis of the cardio-pulmonary systems

Sarcoidosis is a multi-system disease with a wide range of phenotypes. Pulmonary involvement is the most frequently identified target for sarcoidosis and is responsible for the majority of deaths. Cardiac sarcoid is less commonly identified, may be occult, is significantly influenced by race, and can portend an unpredictable and sometimes fatal outcome. Sarcoidosis remains an enigmatic disease spectrum of unknown aetiology, frequently difficult to diagnose and with a variable disease course. This article summarises current views on the diagnosis and management of cardiopulmonary involvement.

14-3-3 inhibition promotes dopaminergic neuron loss and 14-3-3θ overexpression promotes recovery in the MPTP mouse model of Parkinson's disease

14-3-3s are a highly conserved protein family that plays important roles in cell survival and interact with several proteins implicated in Parkinson's disease (PD). Disruption of 14-3-3 expression and function has been implicated in the pathogenesis of PD. We have previously shown that increasing the expression level of 14-3-3θ is protective against rotenone and 1-methyl-4-phenylpyridinium (MPP(+)) in cultured cells. Here, we extend our studies to examine the effects of 14-3-3s in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. We first investigated whether targeted nigral 14-3-3θ overexpression mediated by adeno-associated virus offers neuroprotection against MPTP-induced toxicity. 14-3-3θ overexpression using this approach did not reduce MPTP-induced dopaminergic cell loss in the substantia nigra nor the depletion of dopamine (DA) and its metabolites in the striatum at three weeks after MPTP administration. However, 14-3-3θ-overexpressing mice showed a later partial recovery in striatal DA metabolites at eight weeks after MPTP administration compared to controls, suggesting that 14-3-3θ overexpression may help in the functional recovery of those dopaminergic neurons that survive. Conversely, we investigated whether disrupting 14-3-3 function in transgenic mice expressing the pan 14-3-3 inhibitor difopein exacerbates MPTP-induced toxicity. We found that difopein expression promoted dopaminergic cell loss in response to MPTP treatment. Together, these findings suggest that 14-3-3θ overexpression promotes recovery of DA metabolites whereas 14-3-3 inhibition exacerbates neuron loss in the MPTP mouse model of PD.

Cardiac sarcoidosis: diagnosis and management

Cardiac sarcoidosis is one of the most serious and unpredictable aspects of this disease state. Heart involvement frequently presents with arrhythmias or conduction disease, although myocardial infiltration resulting in congestive heart failure may also occur. The prognosis in cardiac sarcoidosis is highly variable, which relates to the heterogeneous nature of heart involvement and marked differences between racial groups. Electrocardiography and echocardiography often provide the first clue to the diagnosis, but advanced imaging studies using positron emission tomography and MRI, in combination with nuclear isotope perfusion scanning are now essential to the diagnosis and management of this condition. The identification of clinically occult cardiac sarcoidosis and the management of isolated and/or asymptomatic heart involvement remain both challenging and contentious. Corticosteroids remain the first treatment choice with the later substitution of immunosuppressive and steroid-sparing therapies. Heart transplantation is an unusual outcome, but when performed, the results are comparable or better than heart transplantation for other disease states. We review the epidemiology, developments in diagnostic techniques and the management of cardiac sarcoidosis.

Assessment of tuberculosis burden in China using a dynamic disease simulation model

SETTING

Although a preventable and treatable disease, tuberculosis (TB) is among the top 10 causes of death worldwide. A consequence of inadequately treated drug-susceptible TB (DS-TB) is multidrug-resistant TB (MDR-TB).

OBJECTIVES

To improve our understanding of the primary drivers of incidence and prevalence of DS- and MDR-TB in China.

METHODS

The Tuberculosis Disease Transmission Model (TBDTM) uses historical and current disease epidemiology and transmission trends and treatment effectiveness, and accounts for annual changes to these to estimate future DS-TB and MDR-TB burden.

RESULTS

The model shows that in China, by 2050, incidence, prevalence and mortality of DS-TB will decrease by 32%, 50% and 41%, respectively, whereas MDR-TB will increase by respectively 60%, 48% and 35%. Reduction in DS-TB is a result of high treatment and cure rates leading to a decrease in the prevalence of latent tuberculous infection (LTBI), while the increase in MDR-TB is attributed to inappropriate treatment, leading to high transmission of infection and increased LTBI prevalence.

CONCLUSIONS

These results demonstrate a reduction in DS-TB in China over the next 40 years, while MDR-TB will increase. Improvements in the diagnosis and treatment of MDR-TB are needed to counter this threat. The TBDTM tool has potential value in public health practice by demonstrating the impact of interventions and estimating their cost-effectiveness.

Which factors determine the wear rate of large-diameter metal-on-metal hip replacements? Multivariate analysis of two hundred and seventy-six components

BACKGROUND

Determining the relationship between clinical factors and engineering analysis of retrieved hip implants can help our understanding of the mechanism of device failure. This is particularly important for metal-on-metal hip arthroplasties because the most common cause of failure is unexplained. We sought to understand the variation in wear rates in a large series of retrieved metal-on-metal hip arthroplasty components.

METHODS

We prospectively recorded preoperative, intraoperative, and postoperative data to study the effect on both head and cup wear rates of the following variables: patient sex, cause of failure, manufacturer type, resurfacing or modular design, blood cobalt and chromium levels, edge-loading, femoral head size, and cup inclination angle. We analyzed 276 components (138 femoral head and acetabular cup couples) retrieved from failed metal-on-metal hip replacements.

RESULTS

We found a high rate of edge-loading (64%), but only forty-three (31%) of 138 hips had a cup inclination angle of >55°. Multivariate analysis showed that the most important factor responsible for the variation in wear rate was the presence or absence of edge-loading, even when adjusted for cup inclination angle. Strong positive correlations were found between acetabular cup and femoral head wear rates and between wear rates and both blood cobalt and chromium ion levels.

CONCLUSIONS

Multivariate analysis of nine factors found that edge-loading was the most important predictor of wear rate and occurred in two-thirds of failed metal-on-metal hip replacements. The majority did not have excessive cup inclination angles: 68% had an inclination angle of ≤55°. This finding, together with the relatively low median wear rate of the components in our study, suggests that cup position and/or wear rate may not be the only outcome related to failure of metal-on-metal hip replacements.

Synovial fluid lubrication of artificial joints: protein film formation and composition

Despite design improvements, wear of artificial implants remains a serious health issue particularly for Metal-on-Metal (MoM) hips where the formation of metallic wear debris has been linked to adverse tissue response. Clearly it is important to understand the fundamental lubrication mechanisms which control the wear process. It is usually assumed that MoM hips operate in the ElastoHydrodynamic Lubrication (EHL) regime where film formation is governed by the bulk fluid viscosity; however there is little experimental evidence of this. The current paper critically examines synovial fluid lubrication mechanisms and the effect of synovial fluid chemistry. Two composition parameters were chosen; protein content and pH, both of which are known to change in diseased or post-operative synovial fluid. Film thickness and wear tests were carried out for a series of model synovial fluid solutions. Two distinct film formation mechanisms were identified; an adsorbed surface film and a high-viscosity gel. The entrainment of this gel controls film formation particularly at low speeds. However wear of the femoral head still occurs and this is thought to be due primarily to a tribo-corrosion mechanisms. The implications of this new lubrication mechanism and the effect of different synovial fluid chemistries are examined. One important conclusion is that patient synovial fluid chemistry plays an important role in determining implant wear and the likelihood of failure.

Inlet protein aggregation: a new mechanism for lubricating film formation with model synovial fluids

This paper reports a fundamental study of lubricant film formation with model synovial fluid components (proteins) and bovine serum (BS). The objective was to investigate the role of proteins in the lubrication process. Film thickness was measured by optical interferometry in a ball-on-disc device (mean speed range of 2-60 mm/s). A commercial cobalt-chromium (CoCrMo) metal femoral head was used as the stationary component. The results for BS showed complex time-dependent behaviour, which was not representative of a simple fluid. After a few minutes sliding BS formed a thin adherent film of 10-20 nm, which was attributed to protein absorbance at the surface. This layer was augmented by a hydrodynamic film, which often increased at slow speeds. At the end of the test deposited surface layers of 20-50 nm were measured. Imaging of the contact showed that at slow speeds an apparent 'phase boundary' formed in the inlet just in front of the Hertzian zone. This was associated with the formation of a reservoir of high-viscosity material that periodically moved through the contact forming a much thicker film. The study shows that proteins play an important role in the film-forming process and current lubrication models do not capture these mechanisms.

A comparison of explanted Articular Surface Replacement and Birmingham Hip Resurfacing components

The Articular Surface Replacement (ASR) hip resurfacing arthroplasty has a failure rate of 12.0% at five years, compared with 4.3% for the Birmingham Hip Resurfacing (BHR). We analysed 66 ASR and 64 BHR explanted metal-on-metal hip replacements with the aim of understanding their mechanisms of failure. We measured the linear wear rates of the acetabular and femoral components and analysed the clinical cause of failure, pre-revision blood metal ion levels and orientation of the acetabular component.

There was no significant difference in metal ion levels (chromium, p = 0.82; cobalt, p = 0.40) or head wear rate (p = 0.14) between the two groups. The ASR had a significantly increased rate of wear of the acetabular component (p = 0.03) and a significantly increased occurrence of edge loading (p < 0.005), which can be attributed to differences in design between the ASR and BHR. The effects of differences in design on the in vivo wear rates are discussed: these may provide an explanation as to why the ASR is more sensitive to suboptimal positioning than the BHR.

The relationship between the angle of version and rate of wear of retrieved metal-on-metal resurfacings: a prospective, CT-based study

We measured the orientation of the acetabular and femoral components in 45 patients (33 men, 12 women) with a mean age of 53.4 years (30 to 74) who had undergone revision of metal-on-metal hip resurfacings. Three-dimensional CT was used to measure the inclination and version of the acetabular component, femoral version and the horizontal femoral offset, and the linear wear of the removed acetabular components was measured using a roundness machine. We found that acetabular version and combined version of the acetabular and femoral components were weakly positively correlated with the rate of wear. The acetabular inclination angle was strongly positively correlated with the rate of wear. Femoral version was weakly negatively correlated with the rate of wear. Application of a threshold of > 5 μm/year for the rate of wear in order to separate the revisions into low or high wearing groups showed that more high wearing components were implanted outside Lewinnek's safe zone, but that this was mainly due to the inclination of the acetabular component, which was the only parameter that significantly differed between the groups. We were unable to show that excess version of the acetabular component alone or combined with femoral version was associated with an increase in the rate of wear based on our assessment of version using CT.

Retrieval analysis of 240 metal-on-metal hip components, comparing modular total hip replacement with hip resurfacing

This study compared component wear rates and pre-revision blood metal ions levels in two groups of failed metal-on-metal hip arthroplasties: hip resurfacing and modular total hip replacement (THR).

There was no significant difference in the median rate of linear wear between the groups for both acetabular (p = 0.4633) and femoral (p = 0.0872) components. There was also no significant difference in the median linear wear rates when failed hip resurfacing and modular THR hips of the same type (ASR and Birmingham hip resurfacing (BHR)) were compared.

Unlike other studies of well-functioning hips, there was no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR.

Edge loading was common in both groups, but more common in the resurfacing group (67%) than in the modular group (57%). However, this was not significant (p = 0.3479). We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading. This was supported by visual evidence of impingement on the femur.

These findings show that failed metal-on-metal hip resurfacing and modular THRs have similar component wear rates and are both associated with raised pre-revision blood levels of metal ions.

The assessment of myocardial viability and hibernation using resting thallium imaging

Rest-redistribution thallium-201 imaging is widely used to assess recovery of regional systolic dysfunction in patients with chronic coronary artery disease. In several studies, this technique has demonstrated very high sensitivity but reduced specificity, as reported in general for radionuclide imaging. In clinical terms, this implicates that many dysfunctional territories will not recover after revascularization despite a substantial amount of tracer uptake. Yet, the amount of tracer uptake in a given myocardial segment, although not perfect, remains the best indicator for predicting reversible dysfunction. In fact, the occurrence of redistribution after rest injection is not very common and it does not substantially contribute to the accuracy of the test. However, it is still undetermined whether the presence of redistribution is relevant for prognostic implications.

[Myocardial perfusion scintigraphy. Exact and cost-effective coronary disease imaging--secondary publication]

Mortality rates due to coronary arterial disease (CAD) have declined as result of improved prevention, diagnosis and management, but CAD remains the leading cause of death. Myocardial perfusion scintigraphy (MPS) provides a cost-effective tool for early detection of CAD in symptomatic individuals and can stratify patients according to risk of cardiac events. MPS also provides valuable information to assist clinical decision-making. A large body of evidence supports the current applications of MPS, which has become integral to several guidelines for clinical practice.

Comparing oxalic acid and sucrocide treatments for Varroa destructor (Acari: Varroidae) control under desert conditions

The effectiveness of oxalic acid (OA) and Sucrocide (S) (AVA Chemical Ventures, L.L.C., Portsmouth, NH) in reducing populations of the varroa mite Varroa destructor Anderson & Trueman (Acari: Varroidae) in honey bee, Apis mellifera L. (Hymenoptera: Apidae) colonies was measured under the desert conditions of Arizona, USA. OA and S were applied three times 7 d apart. A 3.2% solution of OA was applied in sugar syrup via a large volume syringe, trickling 5 ml per space between frames in the colony. S was applied at a concentration of 0.625% (mixed with water), according to the label directions, using a compressed air Chapin sprayer at 20 psi to apply 59 ml per frame space. Varroa mites, collected on a sticky board before, during, and after the treatments, were counted to assess the effectiveness of the treatments. This study showed that a desert climate zone did not confer any positive or negative results on the acaricidal properties of OA. Even with brood present in colonies, significant varroa mite mortality occurred in the OA colonies. In contrast, we found that Sucrocide was not effective as a mite control technique. Despite its ability to increase mite mortality in the short-term, varroa mite populations measured posttreatment were not affected any more by Sucrocide than by no treatment at all.