Book chapters will be unavailable on Saturday 24th August between 8am-12pm BST. This is for essential maintenance which will provide improved performance going forwards. Please accept our apologies for any inconvenience caused.
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 email@example.com
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.
We develop a general model to describe a network of interconnected thin viscous sheets, or viscidas, which evolve under the action of surface tension. A junction between two viscidas is analysed by considering a single viscida containing a smoothed corner, where the centreline angle changes rapidly, and then considering the limit as the smoothing tends to zero. The analysis is generalized to derive a simple model for the behaviour at a junction between an arbitrary number of viscidas, which is then coupled to the governing equation for each viscida. We thus obtain a general theory, consisting of
partial differential equations and
algebraic conservation laws, for a system of
viscidas connected at
junctions. This approach provides a framework to understand the fabrication of microstructured optical fibres containing closely spaced holes separated by interconnected thin viscous struts. We show sample solutions for simple networks with
or 3. We also demonstrate that there is no uniquely defined junction model to describe interconnections between viscidas of different thicknesses.
We derive a mathematical model for the drawing of a two-dimensional thin sheet of viscous fluid in the direction of gravity. If the gravitational field is sufficiently strong, then a portion of the sheet experiences a compressive stress and is thus unstable to transverse buckling. We analyse the dependence of the instability and the subsequent evolution on the process parameters, and the mutual coupling between the weakly nonlinear buckling and the stress profile in the sheet. Over long time scales, the sheet centreline ultimately adopts a universal profile, with the bulk of the sheet under tension and a single large bulge caused by a small compressive region near the bottom, and we derive a canonical inner problem that describes this behaviour. The large-time analysis involves a logarithmic asymptotic expansion, and we devise a hybrid asymptotic–numerical scheme that effectively sums the logarithmic series.
In May 2016, the National Academies of Sciences, Engineering, and Medicine (NASEM) released the report “Genetically Engineered Crops: Experiences and Prospects,” summarizing scientific consensus on genetically engineered crops and their implications. NASEM reports aim to give the public and policymakers information on socially relevant science issues. Their impact, however, is not well understood. This analysis combines national pre- and post-report survey data with a large-scale content analysis of Twitter discussion to examine the report’s effect on public perceptions of genetically modified organisms (GMOs). We find that the report’s release corresponded with reduced negativity in Twitter discourse and increased ambivalence in public risk and benefit perceptions of GMOs, mirroring the NASEM report’s conclusions. Surprisingly, this change was most likely for individuals least trusting of scientific studies or university scientists. Our findings indicate that NASEM consensus reports can help shape public discourse, even in, or perhaps because of, the complex information landscape of traditional and social media.
Children with CHD and acquired heart disease have unique, high-risk physiology. They may have a higher risk of adverse tracheal-intubation-associated events, as compared with children with non-cardiac disease.
Materials and methods
We sought to evaluate the occurrence of adverse tracheal-intubation-associated events in children with cardiac disease compared to children with non-cardiac disease. A retrospective analysis of tracheal intubations from 38 international paediatric ICUs was performed using the National Emergency Airway Registry for Children (NEAR4KIDS) quality improvement registry. The primary outcome was the occurrence of any tracheal-intubation-associated event. Secondary outcomes included the occurrence of severe tracheal-intubation-associated events, multiple intubation attempts, and oxygen desaturation.
A total of 8851 intubations were reported between July, 2012 and March, 2016. Cardiac patients were younger, more likely to have haemodynamic instability, and less likely to have respiratory failure as an indication. The overall frequency of tracheal-intubation-associated events was not different (cardiac: 17% versus non-cardiac: 16%, p=0.13), nor was the rate of severe tracheal-intubation-associated events (cardiac: 7% versus non-cardiac: 6%, p=0.11). Tracheal-intubation-associated cardiac arrest occurred more often in cardiac patients (2.80 versus 1.28%; p<0.001), even after adjusting for patient and provider differences (adjusted odds ratio 1.79; p=0.03). Multiple intubation attempts occurred less often in cardiac patients (p=0.04), and oxygen desaturations occurred more often, even after excluding patients with cyanotic heart disease.
The overall incidence of adverse tracheal-intubation-associated events in cardiac patients was not different from that in non-cardiac patients. However, the presence of a cardiac diagnosis was associated with a higher occurrence of both tracheal-intubation-associated cardiac arrest and oxygen desaturation.
Chronic copper (Cu) poisoning is a well recognized problem in sheep and there is evidence that the incidence is increasing as more intensive methods of production are adopted. The interaction between Cu, molybdenum (Mo) and sulphur (S) in ruminants is well known and diets supplemented by Mo and S have been used to reduce the incidence of Cu toxicity in sheep. It has been postulated that Mo reacts with sulphide in the rumen to form thiomolybdate (TM) and that this subsequently combines with dietary and/or tissue Cu to form complexes in which Cu is unavailable to the animal. We have evaluated the response of Cu-dosed sheep to the intravenous administration of TM.
The exhibition and aetiology of abnormal behaviour in the equine is a coping response to a sub-optimal environment (McBride and Cuddeford, 2001). Physical prevention of performance of these behaviours could however lead to compromised welfare so alternative welfare enhancement methods have been sought as alternatives. Nicol (1999) indicated that the cause of weaving as a specific stereotypic behaviour is related to the management of the stabled horse. Enrichment devices have been successful in reducing abnormal behaviour and fostering increased expression of more normal behaviours in many animal species but studies have remained limited in relation to the equine. By strategic placement of mirrors in the stable the current study aimed to reduce the stabled horses need to perform stereotypic weaving behaviour without the use of physical restraint in order to enhance the welfare outcome.
Four horses, two males and two females were housed individually in 10*12m loose boxes and provided with straw bedding.
Over fifteen per cent of domesticated horses exhibit a form of stereotypic behaviour (Luescher, McKeown and Halip, 1991). These behaviours can represent or develop into health and welfare disequilibrium and crib–biting and weaving are two of the most commonly performed behaviours of this type. As these behaviours have been described as having no obvious function (Mason, 1991), procedures concerned with their ultimate prevention have been promoted within the equine industry. The aim of this study was to review the success of the physical, pharmacological, dietary, environmental and surgical methods available to horse owners for the prevention of equine stereotypies.
A total of 300 questionnaires were distributed between riding schools, trekking centres and livery yards throughout the Northern counties of England along with horse owning BSc Equine students at Myerscough College, Lancashire. Of the total, 200 were distributed by post and the remainder researcher administered.
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
The molecular, neurobiological, and physical health impacts of child maltreatment are well established, yet mechanistic pathways remain inadequately defined. Telomere length (TL) decline is an emerging molecular indicator of stress exposure with definitive links to negative health outcomes in maltreated individuals. The multiple confounders endemic to human maltreatment research impede the identification of causal pathways. This study leverages a unique randomized, cross-foster, study design in a naturalistic translational nonhuman primate model of infant maltreatment. At birth, newborn macaques were randomly assigned to either a maltreating or a competent control mother, balancing for sex, biological mother parenting history, and social rank. Offspring TL was measured longitudinally across the first 6 months of life (infancy) from peripheral blood. Hair cortisol accumulation was also determined at 6, 12, and 18 months of age. TL decline was greater in animals randomized to maltreatment, but also interacted with biological mother group. Shorter TL at 6 months was associated with higher mean cortisol levels through 18 months (juvenile period) when controlling for relevant covariates. These results suggest that even under the equivalent social, nutritional, and environmental conditions feasible in naturalistic translational nonhuman primate models, early adverse caregiving results in lasting molecular scars that foreshadow elevated health risk and physiologic dysregulation.
Progressive inefficacy of chemoprophylactic therapy to control gastro-intestinal (GI) nematode infection in sheep has been a major contributory factor in stimulating research into the development of alternative means of internal parasite control. This research aims to investigate the possibilities for selecting UK sheep for increased genetic resistance to naturally acquired GI nematode parasite infections.
The Zadko telescope is a 1 m f/4 Cassegrain telescope, situated in the state of Western Australia about 80-km north of Perth. The facility plays a niche role in Australian astronomy, as it is the only meter class facility in Australia dedicated to automated follow-up imaging of alerts or triggers received from different external instruments/detectors spanning the entire electromagnetic spectrum. Furthermore, the location of the facility at a longitude not covered by other meter class facilities provides an important resource for time critical projects. This paper reviews the status of the Zadko facility and science projects since it began robotic operations in March 2010. We report on major upgrades to the infrastructure and equipment (2012–2014) that has resulted in significantly improved robotic operations. Second, we review the core science projects, which include automated rapid follow-up of gamma ray burst (GRB) optical afterglows, imaging of neutrino counterpart candidates from the ANTARES neutrino observatory, photometry of rare (Barbarian) asteroids, supernovae searches in nearby galaxies. Finally, we discuss participation in newly commencing international projects, including the optical follow-up of gravitational wave (GW) candidates from the United States and European GW observatory network and present first tests for very low latency follow-up of fast radio bursts. In the context of these projects, we outline plans for a future upgrade that will optimise the facility for alert triggered imaging from the radio, optical, high-energy, neutrino, and GW bands.
Two-sided oxidation experiments were recently conducted at 1000-1200°C in flowing steam with samples of sponge-based Zr-1Nb alloy E110. Although the old electrolytic E110 tubing exhibited a high degree of susceptibility to nodular corrosion and experienced breakaway oxidation rates in relatively short time, the new sponge-based E110 has demonstrated steam oxidation behavior comparable to Zircaloy-4. The sponge-based E110 followed the parabolic law, and the derived oxidation rate constant is in good agreement with the Cathcart-Pawel (CP) correlation at 1100-1200°C. For 1000°C oxidation, the weight-gain of sponge-based E110 is much lower than Zircaloy-4. No breakaway oxidation was observed at 1000°C up to 8000 s. Ring compression tests were conducted to evaluate the residual ductility of oxidized samples at room temperature and at 135°C. All sponge-based E110 specimens were still ductile at 135°C after being oxidized up to 20% equivalent cladding reacted at 1000-1200°C. Metallographic examinations were performed on oxidized E110 specimens to correlate material performance with microstructure.
We study theoretically and experimentally how a thin layer of liquid flows along a flexible beam. The flow is modelled using lubrication theory and the substrate is modelled as an elastica which deforms according to the Euler–Bernoulli equation. A constant flux of liquid is supplied at one end of the beam, which is clamped horizontally, while the other end of the beam is free. As the liquid film spreads, its weight causes the beam deflection to increase, which in turn enhances the spreading rate of the liquid. This feedback mechanism causes the front position
and the deflection angle at the front
to go through a number of different power-law behaviours. For early times, the liquid spreads like a horizontal gravity current, with
. For intermediate times, the deflection of the beam leads to rapid acceleration of the liquid layer, with
. Finally, when the beam has sagged to become almost vertical, the liquid film flows downward with
. We demonstrate good agreement between these theoretical predictions and experimental results.
We present EUV light curves for a number of AM Her systems observed either as guest observer targets or with the EUVE Right Angle Program. We have formed light curves for eight AM Her stars and show in our presentation the similarities and differences present. We draw some conclusions by grouping the systems by inclination, magnetic field strength, and accretion region geometry. In order to understand the physical structures responsible for the EUV emissions, we have developed a software model to generate synthetic light curves. We find that the EUV accretion regions in the systems UZ For, VV Pup, and AM Her cannot be fit with a flat spot confined to the white dwarf surface, regardless of its shape or brightness profile. Rather, a small, symmetric, raised spot is the only shape consistent with the data. The light curves for systems EF Eri, RE1149+28, AN UMa, and V834 Cen show evidence for additional structure that precedes the primary accretion region in phase. Our model indicates that a large portion of the light curve in each system is seen in absorption. Finally, in three systems, we detect a very gradual rise and fall in the EUV flux (<5% of the peak flux) at phases when the spot is completely obscured behind the white dwarf (WD) limb. We attribute this detection to emission from the accretion column that decreases exponentially with distance from the WD and detect emission at heights up to 15% of the WD radius.
We present optical identifications of nine previously unidentified extreme ultraviolet (EUV) sources discovered during the Extreme Ultraviolet Explorer (EUVE) satellite surveys. The all-sky survey detected four of the sources and the more sensitive deep survey detected the other five sources. Three of the four all-sky survey sources, EUVE_J1918+59.9, EUVE_J2249+58.5, and EUVE_J2329+41.4, are listed in present catalogs as having possible associations with optical counterparts but without spectral class. The first two of these sources are hot DA white dwarfs showing an optical spectrum with broad Balmer lines. The source EUVE_J2329+41.4 is listed as having a possible association with an unclassified M star. We show that a pair of dMe stars are actually optical counterparts located within the error circle of the EUVE source position. The EUVE_J2114+503 remains unidentified even though all the possible candidates have been studied. Based on the count rates we predict a fainter white dwarf or a cataclysmic variable counterpart for this candidate. All five sources discovered with the EUVE deep survey, EUVE_J0318+184, EUVE_J0419+217, EUVE_J2053−175, EUVE_J2056−171 and EUVE_J2233−096, have been identified as late-type stars. The spectral classes, distances, visual magnitudes, and estimated hydrogen column densities for these EUVE sources are presented.
On May 22, 1989 the Japanese Ginga Team discovered a new X-ray source that was cataloged as GS 2023+338. This source was subsequently identified as coincident in position with a previously known nova cataloged as V404 Cygni. Its last recorded outburst was in 1938 when it rose to about 12th mag. Spectroscopic data were obtained and confirmed the nature of the outburst. Additional ground based data were obtained by us at CTIO and the VLA. The X-ray behavior of this object has been reported to be very unusual and it reached a peak of about 17 crab about one week after discovery. Since then it has varied widely in magnitude at all wavelengths at which it has been studied. We present a brief summary of the observations that have been obtained up to the time of the meeting and shortly thereafter.
The AM Herculis binaries (AM Hers) have high and low accretion states. A model is proposed in which the white dwarf’s rotation acts like an angular momentum storage battery for the binary orbit. The accreted material from the Roche lobe-overflowing secondary charges up this battery, whereas the magnetic torque of the white dwarf on the secondary discharges it back into the binary’s orbit. The Roche lobe’s volume becomes alternately larger and smaller than the secondary’s volume. This alternation causes the mass flow to vary between a high and low rate.