To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Laryngeal amyloidosis represents approximately 1 per cent of all benign laryngeal lesions, and can cause variable symptoms depending on anatomical location and size. Treatment ranges from observation through to endoscopic microsurgery, laser excision and laryngectomy.
To highlight the diversity of presentations, increase awareness of paediatric amyloidosis and update the reader on current management.
Five cases are illustrated. Four adult patients were female, and the one child, the second youngest in the literature, was male. Amyloid deposits were identified in all laryngeal areas, including the supraglottis, glottis and subglottis. Treatment consisted of balloon dilatation, endoscopic excision, laser cruciate incision, and resection with carbon dioxide laser, a microdebrider and coblation wands.
Laryngeal amyloidosis remains a rare and clinically challenging condition. Diagnosis should be considered for unusual appearing submucosal laryngeal lesions. Treatment of this disease needs to be evaluated on a case-by-case basis and managed within an appropriate multidisciplinary team.
This article describes the interdisciplinary methods developed by the UNESCO Libyan Valleys Survey in connection with the study of ancient agriculture. These methods combine the techniques of settlement archaeology with those of the earth sciences and palaeoeconomics. The interactive nature of the enquiry does not resolve all the questions, but it can help to re-shape those questions and suggest new lines of enquiry. The example of the Wadi Mansur is used here to demonstrate the application of both conventional and new techniques and the contribution this can make to our appreciation of ancient land use in an arid zone. This provisional statement of results describes the geomorphology of the wadi, the settlement archaeology, ceramic dating evidence, palaeoeconomic data (including palynological evidence), wadi wall technology and typology.
A fourth season of work was carried out in the Spring of 1984. The centrepiece of the programme was the investigation of the well-preserved farm in the Wadi el-Amud (Lamout). The main farm buildings were excavated, faunal and botanical samples were collected systematically from within and between them, the field systems and sluices were examined in detail and investigations begun on the geomorphological and hydrological context. This report presents the basic description of the archaeological data resulting from excavation and survey; a second report will present the results of the various laboratory studies which were generated by the field work.
The impact of community-associated Clostridium difficile infection (CA-CDI) on patients with spinal cord injuries and disorders (SCI/Ds) is not fully understood. We examined CA-CDI cases among veterans with SCI/D, comparing them with community-onset, healthcare facility-associated (CO-HCFA) cases. Generally, patients with CA-CDI had less comorbidity, less severe CDI, and lower likelihood of antibiotic exposure.
Stressful life events have long been suspected to contribute to multiple sclerosis (MS) disease activity. The few studies examining the relationship between stressful events and neuroimaging markers have been small and inconsistent. This study examined whether different types of stressful events and perceived stress could predict the development of brain lesions.
This was a secondary analysis of 121 patients with MS followed for 48 weeks during a randomized controlled trial comparing stress management therapy for MS (SMT-MS) to a waitlist control (WLC). Patients underwent magnetic resonance imaging (MRI) scans every 8 weeks. Every month, patients completed an interview measure assessing stressful life events and self-report measures of perceived stress, anxiety and depressive symptoms, which were used to predict the presence of gadolinium-enhancing (Gd+) and T2 lesions on MRI scans 29–62 days later. Participants classified stressful events as positive or negative. Negative events were considered ‘major’ if they involved physical threat or threat to the patient's family structure, and ‘moderate’ otherwise.
Positive stressful events predicted decreased risk for subsequent Gd+ lesions in the control group [odds ratio (OR) 0.53 for each additional positive stressful event, 95% confidence interval (CI) 0.30–0.91] and less risk for new or enlarging T2 lesions regardless of group assignment (OR 0.74, 95% CI 0.55–0.99). Across groups, major negative stressful events predicted Gd+ lesions (OR 1.77, 95% CI 1.18–2.64) and new or enlarging T2 lesions (OR 1.57, 95% CI 1.11–2.23) whereas moderate negative stressful events, perceived stress, anxiety and depressive symptoms did not.
Major negative stressful events predict increased risk for Gd+ and T2 lesions whereas positive stressful events predict decreased risk.
Few studies have prospectively investigated psychological morbidity in UK head and neck cancer patients. This study aimed to explore changes in psychological symptoms over time, and associations with patients' tumour and treatment characteristics, including toxicity.
Two hundred and twenty patients were recruited to complete the Hospital Anxiety and Depression Scale and the Late Effects on Normal Tissue (Subjective, Objective, Management and Analytic) (‘LENT-SOMA’) questionnaires, both pre- and post-treatment.
Anxiety was highest pre-treatment (38 per cent) and depressive symptoms peaked at the end of treatment (44 per cent). Anxiety significantly decreased and depression significantly increased, comparing pre- versus post-treatment responses (p < 0.001). Hospital Anxiety and Depression Scale scores were significantly correlated with toxicity, age and chemotherapy (p < 0.01 for all).
This is the first study to analyse the relationship between Hospital Anxiety and Depression Scale scores and toxicity scores in head and neck cancer patients. It lends support for the use of the Hospital Anxiety and Depression Scale and the Late Effects on Normal Tissue (Subjective, Objective, Management and Analytic) questionnaire in routine clinical practice; furthermore, continued surveillance is required at multiple measurement points.
The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
Structural materials in the new Generation IV reactors will operate in harsh radiation conditions coupled with high levels of hydrogen and helium production and will experience severe degradation of mechanical properties. Therefore, understanding of the physical mechanisms responsible for the microstructural evolution and corresponding mechanical property changes is critical. As the involved phenomena are very complex and span in several length scales, a multiscale approach is necessary in order to fully understand the degradation of materials in irradiated environments. In previous work, we used molecular dynamics simulations to develop critical rules for the mobility of dislocations in various iron alloys and their interaction with several types of defects that include, among others, helium bubbles and grain boundaries. In this work, Dislocation Dynamics simulations of iron alloys are used to study the mechanical behavior and the degradation under irradiation of large systems with high dislocation and defect densities.
During foetal development, calcium requirements are met as a consequence of maternal adaptations independent of vitamin D status. In contrast, after birth, dependency on vitamin D appears necessary for calcium metabolism and skeletal health. We used a rodent model (Sprague-Dawley rats), to determine if maternal vitamin D deficiency during pregnancy had a deleterious effect on bone structure at birth. Vitamin D deplete females were maintained under deplete conditions until birth of the pups, whereupon all dams were fed a vitamin D replete diet. Offspring were harvested at birth, and 140 days of age. Bones were analyzed using micro-computed tomography and strength tested to study differences in bone structure, density and strength and subjected to elemental analysis using plasma mass spectrometry to determine strontium, barium and calcium contents. Offspring from deplete mothers displayed altered trabecular parameters in the femur at birth and 140 days of age. In addition, at 140 days of age there was evidence of premature mineralization of the secondary ossification centre of the femoral head. Elemental analysis showed increased strontium uptake in the femur of the developmentally vitamin D-deficient offspring. Vitamin D depletion during development in the offspring may have a long-lasting effect, despite repletion of vitamin D from birth. This may have consequences for human health given the low vitamin D levels seen during pregnancy and current lifestyle of sun avoidance due to the risk of skin cancer.
The electronic structure of delta plutonium (δ-Pu) and plutonium compounds is investigated using photoelectron spectroscopy (PES). Results for δ-Pu show a small component of the valence electronic structure which might reasonably be associated with a 5f6 configuration. PES results for PuTe are used as an indication for the 5f6 configuration due to the presence of atomic multiplet structure. Temperature dependent PES data on δ-Pu indicate a narrow peak centered 20 meV below the Fermi energy and 100 meV wide. The first PES data for PuCoIn5 indicate a 5f electronic structure more localized than the 5fs in the closely related PuCoGa5. There is support from the PES data for a description of Pu materials with an electronic configuration of 5f5 with some admixture of 5f6 as well as a localized/delocalized 5f5 description.
Plutonium oxide heat sources are used to power space missions. The heat produced by alpha decay of the 238 isotope of Pu is converted to electricity in a thermopile, providing electricity during a substantial fraction of the 88 year half-life of the isotope. Decay of the Pu produces helium and uranium, and a fraction of the evolved helium is captured in the oxide matrix. All of the helium produced in decay can in principle be contained in the oxide lattice, where it occupies the tetrahedral sites. Some helium diffuses out at a rate that is somewhat dependent on the form and morphology of the fuel. Rates have previously been measured for oxide aged about 1 year. Current measurements on sealed heat sources as old as 34 years indicate that the rate of diffusion has changed only slightly over time. Possible mechanisms for helium release include bubble diffusion, point defect migration, agglomeration and movement of He at grain boundaries, and volume diffusion through the lattice sites. We observe primarily diffusion from site to site within the lattice, with an activation energy of 18.7 kcal/mole, independent of point defect movement, despite the rising concentration of helium in the lattice over time and the accumulation of radiation damage within the lattice. Because of the slow diffusion of helium from the fuel to the headspace, heat sources are anticipated to be stable over a long lifetime.
The five solid-solid phase transformations of pure Pu are typically represented in idealized thermal expansion plots as having sharp onsets and finishes with linear expansion behavior between the transitions. These behaviors are in reality less common, and the various transitions may have bursting behavior, curved onsets and finishes, and non-linear thermal expansion. In this presentation we will review the transformation behavior of diverse set of pure Pu types. These types include zone-refined pure Pu, electro-refined pure Pu, pure Pu doped with 1000 appm Ga, and alpha-phase Pu within an as-cast 1.9 atomic. % Ga alloy.
The standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy , x-ray absorption spectroscopy [1,2,3,4], electron energy loss spectroscopy [2,3,4], Fano Effect measurements , and Bremstrahlung Isochromat Spectroscopy , including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples. [2,3,6]
Martensitic transformations can occur via two modes: thermoelastic and burst. In thermoelastic martensites, deformation can be accommodated elastically and transformations occur smoothly with changes in temperature or stress. Burst martensitic transformations require both elastic and plastic deformation to accommodate strain; individual martensite particles form at the speed of sound, and the overall accumulation of martensite may increase in discrete, incremental steps. Here, we examine a unique martensitic transformation and reversion in a Pu-2.0 at% Ga alloy and show evidence that they proceed via the burst mode. Upon cooling from ambient conditions, the metastable delta phase partially transforms martensitically to the alpha-prime phase with a volume contraction of 20%. This large volume change suggests a burst transformation. Furthermore, using differential scanning calorimetry (DSC), we observed that the alpha-prime to delta reversion proceeds in discrete increments, which appear as sharp peaks in DSC data. The DSC data is compared to similar results obtained using dilatometry and resistometry. This incremental progression is believed to be the result of autocatalytic cascades of many alpha-prime particles reverting nearly-simultaneously to the delta phase. Finite-element modeling suggests that residual stresses in the regions of reverted alpha-prime particles may catalyze (or retard) additional transformation. These stresses could initiate cascades of alpha-prime particles that revert nearly-simultaneously. The cascades are likely quenched by stress and/or temperature changes resulting from the transformation itself. During the forward delta to alpha-prime transformation, burst events are not observed with the above techniques. The transformation, however, is still expected to proceed via the burst martensite mode because of the large volume changes required. Because alpha-prime must be nucleated in the delta matrix before it can grow as an individual burst, the transformation may not occur cooperatively. These individual bursts may be too small to be resolved by the above techniques, and the signal observed corresponds to a cumulative total of all the events.
We have developed an amino-functional silicone resin to toughen epoxies which, when prereacted with the epoxy function in resins, undergoes in-situ phase separation during final epoxy curing. SEM analyses of the morphology of fracture surfaces of MY720- DDS, Epon 828-DDS and other epoxy matrices modified with the silicone resin showed rough surfaces with the formation of very uniform <10 μm spheres. Silicon and sulfur elemental distribution mapping showed silicon rich spheres embedded in an epoxy matrix. We report cavitation, particle debonding and pull-out, and an increases in fracture surface area as possible modes of toughening. Silicone modified materials give improvements in slow strain rate G1c fracture toughness measurements of 250–400%, similar to carboxy terminated polybutadiene-acrylonitrile copolymer (CTBN) modifiers, but with a much smaller flexural modulus loss. The Tg of the modified epoxy matrices are maintained, moisture resistance is improved, and flammability is reduced.