Crystallisation in basaltic magmas revealed via in situ 4D synchrotron X-ray microtomography.

Magma crystallisation is a fundamental process driving eruptions and controlling the style of volcanic activity. Crystal nucleation delay, heterogeneous and homogeneous nucleation and crystal growth are all time-dependent processes, however, there is a paucity of real-time experimental data on crystal nucleation and growth kinetics, particularly at the beginning of crystallisation when conditions are far from equilibrium. Here, we reveal the first in situ 3D time-dependent observations of crystal nucleation and growth kinetics in a natural magma, reproducing the crystallisation occurring in real-time during a lava flow, by combining a bespoke high-temperature environmental cell with fast synchrotron X-ray microtomography. We find that both crystal nucleation and growth occur in pulses, with the first crystallisation wave producing a relatively low volume fraction of crystals and hence negligible influence on magma viscosity. This result explains why some lava flows cover kilometres in a few hours from eruption inception, highlighting the hazard posed by fast-moving lava flows. We use our observations to quantify disequilibrium crystallisation in basaltic magmas using an empirical model. Our results demonstrate the potential of in situ 3D time-dependent experiments and have fundamental implications for the rheological evolution of basaltic lava flows, aiding flow modelling, eruption forecasting and hazard management.

The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density.

OBJECTIVES: Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls. METHODS: Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression. RESULTS: BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm2vs 6.55/cm2vs 5.25/cm2). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls. CONCLUSION: BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant.Cite this article: A. Jin, J. Cobb, U. Hansen, R. Bhattacharya, C. Reinhard, N. Vo, R. Atwood, J. Li, A. Karunaratne, C. Wiles, R. Abel. The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density. Bone Joint Res 2017;6:602-609. DOI: 10.1302/2046-3758.610.BJR-2016-0321.R1.

Three-dimensional rendering of otolith growth using phase contrast synchrotron tomography.

A three-dimensional computer reconstruction of a plaice Pleuronectes platessa otolith is presented from data acquired by the Diamond Light synchrotron, beamline I12, X-ray source, a high energy (53-150 keV) source particularly well suited to the study of dense objects. The data allowed non-destructive rendering of otolith structure, and for the first time allows otolith annuli (internal ring structures) to be analysed in X-ray tomographic images.

Transgranular liquation cracking of grains in the semi-solid state.

Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ∼480 µm, at 555 °C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism.

Employing temporal self-similarity across the entire time domain in computed tomography reconstruction.

There are many cases where one needs to limit the X-ray dose, or the number of projections, or both, for high frame rate (fast) imaging. Normally, it improves temporal resolution but reduces the spatial resolution of the reconstructed data. Fortunately, the redundancy of information in the temporal domain can be employed to improve spatial resolution. In this paper, we propose a novel regularizer for iterative reconstruction of time-lapse computed tomography. The non-local penalty term is driven by the available prior information and employs all available temporal data to improve the spatial resolution of each individual time frame. A high-resolution prior image from the same or a different imaging modality is used to enhance edges which remain stationary throughout the acquisition time while dynamic features tend to be regularized spatially. Effective computational performance together with robust improvement in spatial and temporal resolution makes the proposed method a competitive tool to state-of-the-art techniques.

Revealing the micromechanisms behind semi-solid metal deformation with time-resolved X-ray tomography.

The behaviour of granular solid-liquid mixtures is key when deforming a wide range of materials from cornstarch slurries to soils, rock and magma flows. Here we demonstrate that treating semi-solid alloys as a granular fluid is critical to understanding flow behaviour and defect formation during casting. Using synchrotron X-ray tomography, we directly measure the discrete grain response during uniaxial compression. We show that the stress-strain response at 64-93% solid is due to the shear-induced dilation of discrete rearranging grains. This leads to the counter-intuitive result that, in unfed samples, compression can open internal pores and draw the free surface into the liquid, resulting in cracking. A soil mechanics approach shows that, irrespective of initial solid fraction, the solid packing density moves towards a constant value during deformation, consistent with the existence of a critical state in mushy alloys analogous to soils.

US Hemophilia Treatment Center population trends 1990-2010: patient diagnoses, demographics, health services utilization.

For several decades, US government agencies have partially supported regional networks of Hemophilia Treatment Centers (HTC). HTC multidisciplinary teams provide comprehensive and coordinated diagnosis, treatment, prevention, education, outreach and surveillance services to improve the health of people with genetic bleeding disorders. However, national data are scarce on HTC-patient population trends and services. The aim of the study was to examine national trends over the past 20 years in patient diagnoses, demographics and health services utilization among the Health Resources and Services Administration (HRSA) and Centers for Disease Control and Prevention (CDC)-supported HTC network. Diagnoses, demographics and health services utilization data from 1990 to 2010 were aggregated from all HTCs using the Hemophilia Data Set (HDS). From 1990 to 2010, the HTC population grew 90% from 17 177 to 32 612. HTC patients with von Willebrand's disease increased by 148%, females by 346%, Hispanic patients by 236% and African Americans by 104%. Four thousand and seventy-five deaths were reported. From 2002 to 2010, annual comprehensive evaluations grew 38%, and persons with severe haemophilia on a home intravenous therapy programme rose 37%. In 2010, 46% of patients were less than 18 years vs. 24% for the general US population. The Hemophilia Data Set documents the growth and diversity of the US Hemophilia Treatment Center Network's patient population and services. Despite disproportionate deaths due to HIV, the HTC patient base grew faster than the general US population. The HDS is a vital national public health registry for this rare-disorder population.

A marvellous and authentic account: the first written report of haemophilia in America.

The first written record of haemophilia in America is reputed to be the 1791 newspaper obituary of Isaac Zoll. The earlier, original publication of this obituary is identified.

Modeling the investment casting of a titanium crown.

OBJECTIVE: The objective of this study was to apply computational modeling tools to assist in the design of titanium dental castings. The tools developed should incorporate state-of-the-art micromodels to predict the depth to which the mechanical properties of the crown are affected by contamination from the mold. The model should also be validated by comparison of macro- and micro-defects found in a typical investment cast titanium tooth crown. METHODS: Crowns were hand-waxed and investment cast in commercial purity grade 1 (CP-1) titanium by a commercial dental laboratory. The castings were analyzed using X-ray microtomography (XMT). Following sectioning, analysis continued with optical and scanning electron microscopy, and microhardness testing. An in-house cellular-automata solidification and finite-difference diffusion program was coupled with a commercial casting program to model the investment casting process. A three-dimensional (3D) digital image generated by X-ray tomography was used to generate an accurate geometric representation of a molar crown casting. Previously reported work was significantly expanded upon by including transport of dissolved oxygen and impurity sources upon the arbitrarily shaped surface of the crown, and improved coupling of micro- and macro-scale simulations. RESULTS: Macroscale modeling was found to be sufficient to accurately predict the location of the large internal porosity. These are shrinkage pores located in the thick sections of the cusp. The model was used to determine the influence of sprue design on the size and location of these pores. Combining microscale with macroscale modeling allowed the microstructure and depth of contamination to be predicted qualitatively. This combined model predicted a surprising result--the dissolution of silicon from the mold into the molten titanium is sufficient to depress the freezing point of the liquid metal such that the crown solidifies the subsurface. Solidification then progresses inwards and back out to the surface through the silicon-enriched near-surface layer. The microstructure and compositional analysis of the near-surface region are consistent with this prediction. SIGNIFICANCE: A multiscale model was developed and validated, which can be used to design CP-Ti dental castings to minimize both macro- and micro-defects, including shrinkage porosity, grain size and the extent of surface contamination due to reaction with the mold material. The model predicted the surprising result that the extent of Si contamination from the mold was sufficient to suppress the liquidus temperature to the extent that the surface (to a depth of approximately 100 microm) of the casting solidifies after the bulk. This significantly increases the oxygen pickup, thereby increasing the depth of formation of alpha casing. The trend towards mold materials with reduced Si in order to produce easier-to-finish titanium castings is a correct approach.

Modeling the surface contamination of dental titanium investment castings.

OBJECTIVE: The objective of this study was to develop a computational tool for assisting the design of titanium dental castings with minimal defects and to compare computational simulations with casting experiments. METHODS: Modeling. An in-house cellular-automata solidification and finite-difference diffusion program was coupled with a commercial casting program and applied to (a) simple geometric wedge models and (b) a 3D-laser scan of a molar crown casting. Experimental. Wedges and molar crowns were hand-waxed and investment cast in commercial purity grade 1 (CP-1) titanium by a commercial dental laboratory. The castings were sectioned and analyzed using light and scanning electron microscopy, X-ray microanalysis, and microhardness testing. RESULTS: In the wedge sample, contamination with impurities (Al, Si), including intermetallic precipitates, was found to extend to a depth ranging from 30 to 120 microm depending on the section thickness and hence the local cooling rate. Microstructural and mechanical (hardness) effects were found to a depth ranging from 80 to 250 microm. The coupled micro/macro model predictions showed reasonable agreement for the pattern of contamination. SIGNIFICANCE: Dental and medical applications demand close dimensional tolerance and freedom from surface impurities and structural flaws in castings having unique shapes. The ability to predict the structural, mechanical, and chemical changes resulting from the casting process will help to design the casting and post-casting processes to minimize these problems.

Epidemiologic characteristics of an outbreak of serogroup C meningococcal disease and the public health response.

An outbreak of serogroup C meningococcal disease occurred in six counties in the State of Washington from January 1989 through mid-1991. This report describes epidemiologic data collected from hospitals and health departments, the results of multilocus enzyme electrophoresis of isolates, and the vaccination of high-risk populations in one county. A total of 45 confirmed or probable cases (10 per 100,000 population) occurred. Infants younger than age 1, Hispanics and American Indians, and low-income populations had high attack rates. Nine (20 percent) patients died. The predominant enzyme type, ET-22, had not been detected previously in Washington. More than 22,000 persons were vaccinated in one of the counties. Major challenges to health care personnel included deciding when and where to employ vaccination, obtaining sufficient vaccine, and responding to public anxiety.

Intraoperative cardiopulmonary resuscitation in the prone position.

Cardiopulmonary resuscitation (CPR) occasionally is necessary in the operating-room setting. In such instances, it may be difficult to perform CPR if the patient is in the prone position. Although the supine position is optimal for CPR, it may not be feasible because of the risks of damage to craniospinal structures. The authors present the case of a 12-year-old boy who had cardiac arrest during spinal fusion. Successful CPR was performed with the patient in the prone position, with the use of "reversed precordial compressions," and the patient was resuscitated despite 7 minutes of asystole. Effective cardiac output was maintained and was confirmed by systolic blood pressure readings of 80 to 90 mm Hg on both the arterial catheter waveform and the noninvasive blood pressure cuff, by a waveform and the reading on the pulse oximeter, and by the presence of end-tidal carbon dioxide.

Anesthetic considerations in the child with Gaucher disease.

We present the case of a 7-month-old girl with Gaucher disease who required anesthetic care during laryngoscopy, bronchoscopy, and central line placement. Gaucher disease is a familial disorder of lipid catabolism with autosomal recessive inheritance. Due to the defective function of the enzyme glucosylceramide beta-glucosidase, glycosphingolipids accumulate, leading to end-organ dysfunction. Three clinical variants of the disease, which differ in age of onset, degree of central nervous system (CNS) involvement, and frequency in the population, have been described. Of concern to the anesthesiologist is the occurrence of significant CNS dysfunction in types II and III, with seizures, gastroesophageal reflux, and chronic aspiration. Bulbar involvement and infiltration of the upper airway with glycolipids may lead to upper airway obstruction. Additionally, hepatosplenomegaly, present in all three variants, may lead to hypersplenism with thrombocytopenia and anemia. Preoperative identification of the associated end-organ dysfunction will allow the safe provision of anesthetic care for these children.

Two types of delinquents and their institutional adjustment.

This research tested a typology classifying 326 incarcerated delinquent boys as buoyant or beset, depending on their level of anxiety and depression at intake. Findings reveal that the two types of boys differed in some aspects of life history and personality, that the buoyant type adjusted better to the institution's group-oriented treatment program, and that buoyant and beset boys responded differentially to some components of the treatment. Implications are drawn regarding the usefulness of the typology for guiding differential treatment.

Crossing the midline as a function of distance from midline.

This study examined the effect of differential block placement on the frequency of midline crossing during the Space Visualization test (SV) of the Southern California Sensory Integration Tests. The SV test was administered at distances of 0.75, 3.00, and 6.00 inches to a group of 71 normal right-handed boys (ages 5 and 7 years) to obtain the Space Visualization Contralateral Use score (SVCU) and the Space Visualization Contralateral Use Percentage score (SVCU percent). Space Visualization (SV) adjusted scores were also obtained to examine the effect of differential block placement on visual perception scores. The analyses for the SVCU and SVCU percent scores showed that age and distance were significant. Analysis of variance of the SV adjusted standard score indicated that trial, but not distance or age, was significant. There was a significant age-by-trial interaction. The need for a standard protocol for block placement during the administration of the SV test was shown. Future research needs were identified.

Laparoscopic sterilization with room air insufflation: preliminary report.

Laparoscopic sterilizations can be safely performed using room air insufflation. In a series of 400 procedures, the rates of surgical complications were comparable to other laparoscopy studies in which high-pressure gas was used. The purported problems associated with room air insufflation were not encountered in this study.

PIP: This paper reexamines the use of room air as the insufflating medium for voluntary sterilizations. 400 sterilization procedures were performed at the Centro Medico in El Salvador. The 1st 100 sterilizations utilized a standard laparoscopy technique that familiarized the operating physician with the laprocator. The next 300 sterilizations utilized Hasson's open laparoscopy technique using the Hasson trocar and blunt cannula. In all the procedures, pneumoperitoneum by room air was used for insufflation. Air insufflation was achieved using the KLI insufflator which can deliver either gas under pressure or air with a pneumatic bulb. No surgical recovery period or follow up complications were observed in the standard laparoscopy series. Of the 300 open laparoscopy procedures, 1 case (0.3%) of mesosalpingial injury without bleeding was recorded as a surgical complication. Follow-up complications were 2 cases (0.7%) of urinary tract infections and 2 cases (0.7%) of incision inflammation that required medical treatment with only aspirin or penicillin. Reported sites of pain during standard laparoscopic procedures were pelvic (5%) and shoulders (2%). Benefits of use of room-air insufflation are universal availability, low cost, simplification of procedure, reduction of cost of backup equipment and reduction of performance time. The reported disadvantages of room air insufflation--pain, air embolism, infection or death--did not occur in this series.

Organic mercury exposure from fungicide-contaminated eggs.

During a period of 50 to 55 days from early January to March 2, 1979, 14 members of an extended family in Yakima, Washington, ate eggs contaminated with organic mercury. Seed grain which had been treated with a mercurial fungicide and fed to chickens in a home flock was the source of exposure. Blood mercury levels in family members ranged from 0.9 to 20.2 ppb and correlated positively with average daily egg consumption (r = 0.92). There were no symptoms or physical signs of organic mercury intoxication. Prompt confiscation of the contaminated grain, eggs, and chicken flock terminated the exposure and may have prevented the development of serious illness.

Postvasectomy residual sperm pregnancy.

PIP: A pregnancy occuring within a few months after a successful vasectomy is sometimes attributed by a skeptical physician to sexual involvement by the spouse with a nonvasectomized man. This assumption may be unjustified because of the fact that after a vasectomy, some residual sperm which are viable enough to cause pregnancy could remain stored distal to the site of occlusion. The Maternal and Child Health Center of Taiwan documented a case history of a 32-year-old father of 2 who impregnated his wife approximately 38 days, and at least 9 ejaculations, after a successful vasectomy. The patient had no urogenital abnormalities and had an uneventful vasectomy procedure. He resumed intercourse with his wife 8 days after vasectomy and returned for 5 semen tests during the year after vasectomy. The patient's 28-year-old wife had her last menses 24 days after the vasectomy, and pregnancy test 57 days after the vasectomy confirmed the suspicion of pregnancy. Vacuum aspiration terminated the pregnancy 2 days later. There was no doubt or question at all that the patient was his wife's only sexual partner. The authors concluded that based on examination of several thousand postvasectomy semen specimens, the distribution of the biologic limits for residual sperm viability is an asymmetrical distribution skewed to the right, suggesting that the limits may even exceed 38 days for some individuals. Thus physicians should be careful in evaluating a pregnancy which occurs a few months after a successful vasectomy.^ieng

Third party vision care today - tomorrow.

Third party vision care and different delivery and payment methods are defined. How the delivery or payment affects what percentage of those covered will seek care is discussed. Also presented is a profile of the growth of vision care to the present, a projection of future growth and some of the ways providers will be affected.