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The air gap technique (AGT) is an approach to radiation dose optimisation during fluoroscopy where an “air gap” is used in place of an anti-scatter grid to reduce scatter irradiation. The AGT is effective in adults but remains largely untested in children. Effects are expected to vary depending on patient size and the amount of scatter irradiation produced.
Fluoroscopy and cineangiography were performed using a Phillips Allura Fluoroscope on tissue simulation anthropomorphic phantoms representing a neonate, 5-year-old, and teenager. Monte Carlo simulations were then used to estimate effective radiation dose first using a standard recommended imaging approach and then repeated using the AGT. Objective image quality assessments were performed using an image quality phantom.
Effective radiation doses for the neonate and 5-year-old phantom increased consistently (2–92%) when the AGT was used compared to the standard recommended imaging approaches in which the anti-scatter grid is removed at baseline. In the teenage phantom, the AGT reduced effective doses by 5–59%, with greater dose reductions for imaging across the greater thoracic dimension of lateral projection. The AGT increased geometric magnification but with no detectable change in image blur or contrast differentiation.
The AGT is an effective approach for dose reduction in larger patients, particularly for lateral imaging. Compared to the current dose optimisation guidelines, the technique may be harmful in smaller children where scatter irradiation is minimal.
We discuss the process of estimating the ecosystem service value (ESV) for provisioning of non-timber forest products (NTFPs) to market, with a focus on the United States. NTFPs are harvested throughout the U.S. for numerous purposes, and those sold in market contribute significantly to household and local economies. While estimates of ESV can aid decision-making related to conservation and management, NTFPs have been generally neglected. We discuss challenges and approaches for prioritizing valuation, quantifying production, measuring costs and benefits, and finding data sources. Many NTFP markets are informal, and market players may have an interest in withholding information. Data about geographic and temporal distribution, production cost, quantity harvested, and price may therefore be limited. In two case studies, we explore the nuances of estimating ESV of forests for medicinal products.
Common mental health problems affect a quarter of the population. Online cognitive–behavioural therapy (CBT) is increasingly used, but the factors modulating response to this treatment modality remain unclear.
This study aims to explore the demographic and clinical predictors of response to one-to-one CBT delivered via the internet.
Real-world clinical outcomes data were collected from 2211 NHS England patients completing a course of CBT delivered by a trained clinician via the internet. Logistic regression analyses were performed using patient and service variables to identify significant predictors of response to treatment.
Multiple patient variables were significantly associated with positive response to treatment including older age, absence of long-term physical comorbidities and lower symptom severity at start of treatment. Service variables associated with positive response to treatment included shorter waiting times for initial assessment and longer treatment durations in terms of the number of sessions.
Knowledge of which patient and service variables are associated with good clinical outcomes can be used to develop personalised treatment programmes, as part of a quality improvement cycle aiming to drive up standards in mental healthcare. This study exemplifies translational research put into practice and deployed at scale in the National Health Service, demonstrating the value of technology-enabled treatment delivery not only in facilitating access to care, but in enabling accelerated data capture for clinical research purposes.
Declaration of interest
A.C., S.B., V.T., K.I., S.F., A.R., A.H. and A.D.B. are employees or board members of the sponsor. S.R.C. consults for Cambridge Cognition and Shire. Keywords: Anxiety disorders; cognitive behavioural therapies; depressive disorders; individual psychotherapy
We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80–200 keV electron beams.
On 30 May 2012, Surrey and Sussex Health Protection Unit was called by five nurseries reporting children and staff with sudden onset vomiting approximately an hour after finishing their lunch that day. Over the following 24 h 50 further nurseries supplied by the same company reported cases of vomiting (182 children, 18 staff affected). Epidemiological investigations were undertaken in order to identify the cause of the outbreak and prevent further cases. Investigations demonstrated a nursery-level attack rate of 55 out of 87 nurseries (63·2%, 95% confidence interval 52·2–73·3). Microbiological tests confirmed the presence of Bacillus cereus in food and environmental samples from the catering company and one nursery. This was considered microbiologically and epidemiologically consistent with toxin from this bacterium causing the outbreak. Laboratory investigations showed that the conditions used by the caterer for soaking of pearl haricot beans (known as navy bean in the USA) used in one of the foods supplied to the nurseries prior to cooking, was likely to have provided sufficient growth and toxin production of B. cereus to cause illness. This large outbreak demonstrates the need for careful temperature control in food preparation.
On January 12, 2010, a major earthquake in Haiti resulted in approximately 212 000 deaths, 300 000 injuries, and more than 1.2 million internally displaced people, making it the most devastating disaster in Haiti's recorded history. Six academic medical centers from the city of Chicago established an interinstitutional collaborative initiative, the Chicago Medical Response, in partnership with nongovernmental organizations (NGOs) in Haiti that provided a sustainable response, sending medical teams to Haiti on a weekly basis for several months. More than 475 medical volunteers were identified, of whom 158 were deployed to Haiti by April 1, 2010. This article presents the shared experiences, observations, and lessons learned by all of the participating institutions. Specifically, it describes the factors that provided the framework for the collaborative initiative, the communication networks that contributed to the ongoing response, the operational aspects of deploying successive medical teams, and the benefits to the institutions as well as to the NGOs and Haitian medical system, along with the challenges facing those institutions individually and collectively. Academic medical institutions can provide a major reservoir of highly qualified volunteer medical personnel that complement the needs of NGOs in disasters for a sustainable medical response. Support of such collaborative initiatives is required to ensure generalizability and sustainability.
(Disaster Med Public Health Preparedness. 2010;4:169-173)
During the past decade, the number known shallow-amplitude, yet totally eclipsing, extreme-mass-ratio binaries has increased from one (AW UMa, which is now in doubt) to about a dozen. Statistics are accumulating that will tell us the nature of these once rare systems. These individual interacting field binaries are believed to be the progenitors of FK Comae-type fast-rotating subgiants, which are similar to the cluster stars called ‘variable blue stragglers.’ We review our recent observations and new analyses of the individual systems, V409 Hya, GSC 1283 0053 Ori, GSC 2537 520 CVn, using the 2007 Wilson Code and summarize results from our previous observations (V802 Aql, V902 Sgr) and those from the literature (e.g., CK Boo, GR Vir, HV Aqr, UY UMa, EM Pis, CU Tau, TV Mus) to disclose a preliminary picture of the character of this interesting class of binary stars.
Using a 337 μm gas maser (Gebbie, Stone & Findlay 1965; Gebbie, Stone, Slough, Chamberlain & Sheraton 1966) it is possible to obtain precise measurements of the submillimetre absorption and phase shift occurring in specimens of each of the phases of matter and results have already been reported for the soild, liquid and gaseous states (Chamberlain & Gebbie 1965; Gebbie, Stone, Findlay & Pyatt 1965; Chamberlain, Werner, Gebbie & Slough 1967;, Chamberlain, Findlay & Gebbie 1965).
We have found photometric indications that Interacting Eclipsing Binaries of early to mid F spectral type (and possibly A) have strong magnetic activity which would arise from convective atmospheres. Light curve solutions and periodicity studies revealing spots, magnetic breaking and magnetic cycles are presented in XZ CMi, V965 Cyg and V963 Cyg.
Approximations to the scattering of linear surface gravity waves on water of varying quiescent depth are investigated by means of a variational approach. Previous authors have used wave modes associated with the constant depth case to approximate the velocity potential, leading to a system of coupled differential equations. Here it is shown that a transformation of the dependent variables results in a much simplified differential equation system which in turn leads to a new multi-mode ‘mild-slope’ approximation. Further, the effect of adding a bed mode is examined and clarified. A systematic analytic method is presented for evaluating inner products that arise and numerical experiments for two-dimensional scattering are used to examine the performance of the new approximations.
Background. The use of strategies to aid performance when undertaking neuropsychological tasks is dependent on intact fronto-striatal circuitry, and growing evidence suggests impaired spontaneous use of strategies in patients with obsessive–compulsive disorder (OCD). However, studies to date have not examined the effects of strategy training on task performance in OCD or in trichotillomania (compulsive hair-pulling, a condition that has been argued to share overlap with OCD in terms of phenomenology and co-morbidity).
Method. The ability to generate novel visuospatial sequences using a computer interface was examined before and after undertaking optimal strategy training in 20 OCD patients, 17 trichotillomania patients, and 20 controls (matched for age, education, and IQ).
Results. OCD patients failed to improve ability to generate novel sequences above baseline despite successfully completing strategy training to the same extent as other groups. In contrast, performance of trichotillomania patients improved significantly after training to the same extent as controls. Groups did not differ on memory span, trial-by-trial action monitoring, or ability to generate novel visuospatial sequences prior to strategy training.
Conclusions. Strategy implementation deficits, suggestive of cognitive inflexibility and fronto-striatal dysfunction, appear integral to the neurocognitive profile of OCD but not trichotillomania. Future research should investigate cognitive flexibility in obsessive–compulsive spectrum disorders using a variety of paradigms, and clarify the contribution of specific neural structures and transmitter systems to deficits reported.
The scattering of waves in a two-layer fluid of varying mean depth is examined in a three-dimensional context using linear theory. A variational technique is used to construct a particular type of approximation which has the effect of removing the vertical coordinate and reducing the problem to two coupled partial differential equations in two independent variables. A transformation of this differential equation system leads to a particularly simple approximate representation of the scattering process. The theory is applied to two-dimensional scattering, for which a set of symmetry relations is derived. A selection of numerical results is presented to illustrate the principle interest in the problem, namely the energy transfer between surface and interfacial waves induced by bed undulations.
The scattering of plane surface water waves by both surface-piercing and submerged
axisymmetric bed formations has been investigated by a number of authors. We
extend previous contributions in two ways: we employ the recently derived modified
mild-slope equation to approximate the fluid motion and we consider arbitrary
axisymmetric topography, subject only to the restriction imposed by the mild-slope
approximation. We thereby derive a robust method for calculating the scattered
wave field for the small seabed slopes typical of most real situations and make a
contribution to the phenomena of near-resonance and near-trapping over submerged
axisymmetric shoals, which have previously been detected for only one idealized
Four titanate ceramics were characterized and tested. These ceramics were similar to those proposed for Pu disposition, with Ce as a surrogate for Pu. The baseline ceramic contained Ti, U, Ca, Hf, Gd, and Ce, and was made up of only four crystalline phases: pyrochlore, zirconolite, rutile, and brannerite. The three other ceramics contained different amounts of impurities that are expected in the feed. Impurities are defined as any element other than Ti, U, Ca, Hf, Gd, and Ce. The ceramics that contained impurities contained different phases than the baseline. The addition of impurities led to the absence of brannerite and the presence of amorphous silicate, Ca-Al-Ti, and perovskite phases. The results from 3 day, 90°C MCC-I tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics altered the phase assemblages, which in turn, affected the corrosion behavior.
The aqueous corrosion behavior of a zirconolite-rich titanate ceramic was investigated with the aim of describing the rate-controlling process or processes. This titanate ceramic is similar to SYNROC and is proposed as immobilization materials for surplus Pu. The corrosion behavior was described with results from MCC-I and PCT-B static dissolution tests. Three important observations were made: a) Ca is released at a constant rate [7×10−5 g/(m2 day)] in PCT-B tests for up to two years; b) the leachates from PCT-B tests are saturated with respect to both rutile and anatase, and c) the release rates for Pu and Gd increase with time (up to two years) in PCT-B tests. The first observation suggests that the ceramics continue to corrode at a low rate for at least 2 years in PCT-B tests. The second observation suggests that the approach to saturation with respect to these TiO2 phases does not limit the corrosion rate in PCT-B tests. The third observation suggests that the release rate of Pu and Gd are controlled by some unique process or processes, i.e., some process or processes that do not affect the release rate of other elements. While these processes cannot be fully described at this point, two possible explanations, alteration phase formation and grain boundary corrosion are forwarded.
Borosilicate glasses loaded with ∼10 wt % plutonium were found to produce plutonium-silicate alteration phases upon aqueous corrosion under a range of conditions. The phases observed were generally rich in lanthanide (Ln) elements and were related to the lanthanide orthosilicate phases of the monoclinic Ln2SiO5 type. The composition of the phases was variable regarding [Ln]/[Pu] ratio, depending upon type of corrosion test and on the location within the alteration layer. The formation of these phases likely has implications for the incorporation of plutonium into silicate alteration phases during corrosion of titanate ceramics, high-level waste glasses, and spent nuclear fuel.
We report extended x-ray absorption fine structure (EXAFS) spectra from the plutonium LIII edge and x-ray absorption near edge structure (XANES) from the cerium LII edge and plutonium LIII edge in prototype titanate ceramic hosts. The titanate ceramics studied are based upon the hafnium-pyrochlore and zirconolite mineral structures that will serve as an immobilization host for surplus fissile materials. Our samples approximate the composition envelope expected for production materials, which will contain as much as 10.5 weight % fissile plutonium and 21 weight % (natural or depleted) uranium. Three ceramic formulations were studied: one employed cerium as a “surrogate” element, replacing both plutonium and uranium in the ceramic matrix, another formulation contained plutonium in a “baseline” ceramic formulation, and a third contained plutonium in a formulation representing a high-impurity plutonium stream. The cerium XANES from the surrogate ceramic clearly indicates a mixed IIIIV oxidation state for the cerium. In contrast, XANES analysis of the two plutonium-bearing ceramics shows that the plutonium is present almost entirely as Pu(IV) and occupies the calcium site in the zirconolite and pyrochlore phases. The plutonium EXAFS real-space structure shows a strong second-shell peak, clearly distinct from that of PuO2, with remarkably little difference in the plutonium crystal chemistry indicated between the baseline and high-impurity formulations