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.
Recent work has implicated one type of horizontal strabismus (exotropia) as a risk factor for schizophrenia. This new insight raises questions about a potential common developmental origin of the two diseases. Seasonality of births is well established for schizophrenia. Seasonal factors such as light exposure affect eye growth and can cause vision abnormalities, but little is known about seasonality of births in strabismus. We examined birth seasonality in people with horizontal strabismus in a retrospective study in Washoe County, Nevada, and re-examined similar previously obtained data from Osaka, Japan. We then compared seasonal patterns of births between strabismus, refractive error, schizophrenia and congenital toxoplasmosis. Patients with esotropia had a significant seasonality of births, with a deficit in March, then increasing to an excess in September, while patients with exotropia had a distinctly different pattern, with an excess of births in July, gradually decreasing to a deficit in November. These seasonalities were statistically significant with either χ2 or Kolmogorov–Smirnov-type statistics. The birth seasonality of esotropia resembled that for hyperopia, with an increase in amplitude, while the seasonality for myopia involved a phase-shift. There was no correlation between seasonality of births between strabismus and congenital toxoplasmosis. The pattern of an excess of summer births for people with exotropia was remarkably similar to the well-established birth seasonality of one schizophrenia subtype, the deficit syndrome, but not schizophrenia as a whole. This suggests a testable hypothesis: that exotropia may be a risk factor primarily for the deficit type of schizophrenia.
Financial incentives may aid in conservation if they broaden the numbers and types of landowners who engage in protection and conservation management on private land. We examined the hypotheses that financial incentives (1) encourage participation of people with lower autonomous motivation towards conservation and lower self-transcendence (i.e. benevolence and universalism) values compared to participants in similar programmes without such incentives; (2) enable more on-ground works and activities; and (3) enhance feelings of competence and autonomy with respect to conservation actions. We surveyed 193 landowners in private land conservation programmes in Tasmania, only some of whom had received financial incentives. All of these landowners had high self-transcendence values, and autonomous motivation towards the environment. Owners of large properties and participants with higher self-enhancement values, lower self-transcendence values and lower autonomous motivation towards the environment were slightly more likely to engage in incentive programmes. However, people who received funding did not report more conservation actions than people in programmes without incentives. Owners of larger properties receiving incentives reported fewer conservation actions. Thus financial incentives probably recruited a few into nature conservation who may not have otherwise engaged, but did not result in a more intensive level of conservation management. Our results caution against the blanket-use of incentives amongst landowners who may already have values and motivations consistent with environmental action, and point to the need for further research on the socio-psychological characteristics of landowners, to examine the contextual factors that influence the effects of conservation payments.
André (1) gave a construction for translation planes from abelian groups possessing “congruences” of subgroups. Schwerdtfeger (3) constructed the plane over a field F from the group of substitutions x → ax + b (a, b ∊ F; a ≠ 0). In this note we describe a construction (inspired by Schwerdtfeger's work), from groups, of planes which are duals of near-field planes.
If a plane is (l, m)-transitive (cf. 2, p. 67) for some pair of distinct lines l, m, then the central collineations ϕ with axis m and centre on I may be identified with the “proper” points (that is, points not on I or m) of the plane once an origin O is chosen (not on l or m):
Simulation models are used widely in pharmacology, epidemiology and health economics (HEs). However, there have been no attempts to incorporate models from these disciplines into a single integrated model. Accordingly, we explored this linkage to evaluate the epidemiological and economic impact of oseltamivir dose optimisation in supporting pandemic influenza planning in the USA. An HE decision analytic model was linked to a pharmacokinetic/pharmacodynamics (PK/PD) – dynamic transmission model simulating the impact of pandemic influenza with low virulence and low transmissibility and, high virulence and high transmissibility. The cost-utility analysis was from the payer and societal perspectives, comparing oseltamivir 75 and 150 mg twice daily (BID) to no treatment over a 1-year time horizon. Model parameters were derived from published studies. Outcomes were measured as cost per quality-adjusted life year (QALY) gained. Sensitivity analyses were performed to examine the integrated model's robustness. Under both pandemic scenarios, compared to no treatment, the use of oseltamivir 75 or 150 mg BID led to a significant reduction of influenza episodes and influenza-related deaths, translating to substantial savings of QALYs. Overall drug costs were offset by the reduction of both direct and indirect costs, making these two interventions cost-saving from both perspectives. The results were sensitive to the proportion of inpatient presentation at the emergency visit and patients’ quality of life. Integrating PK/PD–EPI/HE models is achievable. Whilst further refinement of this novel linkage model to more closely mimic the reality is needed, the current study has generated useful insights to support influenza pandemic planning.
How do varying levels of inter-group contact affect voter preferences in connection with ethnically radical political candidates and parties? Two competing hypotheses have emerged in the last 60 years: the first, known as the group threat hypothesis, argues that voters from an ethnic or religious group in more ethnically or racially heterogeneous districts will exhibit stronger preferences for ethnically radical political candidates. The contact hypothesis argues that groups living in mixed localities are actually less likely to support ethnic radicals. Both perspectives have found empirical support, but no previous study has offered a theoretical explanation for two seemingly contradictory conclusions. We specify just such a theory, arguing that the effect of district level integration is conditioned by the direction of a group’s share of the national population. We test this theory quantitatively using electoral data from Northern Ireland between 1983 and 2010.
We investigated the effects of host tree on epiphyte diversity, controlling for microclimate. We measured the light profiles of the lower trunks of 20 individuals, each from three host groups (tree ferns, dicots, palms) occupying the understorey in a tropical montane forest in Panama. The per cent cover and species richness of vascular and non-vascular epiphytes were surveyed on the lower trunks of each understorey host. Light varied considerably between trees (5–21% total transmitted light) but mean light level did not vary between types of host. Light was not significant as a covariate with host in any model. Tree ferns had higher covers than dicots and palms of filmy ferns (15%, 0.02% and 0.2%), other ferns (7%, 0% and 0.5%) and other vascular epiphytes (16%, 3% and 3.4%), and greater species richness of vascular epiphytes (filmy ferns: 3, 0.4 and 0.5; other ferns: 2, 0.2 and 0; other vascular: 7, 2 and 2). Dicots had a higher cover of liverworts (53%) than palms (18%) and tree ferns (27%). Palms and tree ferns were the compositional extremes. We conclude that the differences in species composition and cover between the three host groups relate better to physical differences between hosts than differences in light climate.
To evauluate our novel ultrasound model for measurement of optic nerve sheath diameter (ONSD) and determine the intra- and inter-operator variability associated with this technique.
We conducted ten measurements of ONSD per model amongst eight different models with a single experienced operator to examine intra-operator variability. Similarly, we had seven different operators measure the OSND twice in eight different models, in order to determine inter-operator variability analyzed with a three level linear statistical model.
For intra-operator variability, the intra-cluster correlation coefficients for the experienced and novice operators were 0.643 and 0.453 respectively. This displayed improvement in intra-operator variability with experience. The inter-cluster correlation coefficient was 0 for the group of novice operators, indicating negligible difference amongst multiple operators in measuring any given model of ONSD. A strong, statistically significant, linear relationship between the actual model disc size and the ultrasound ONSD measures was identified, implying the reliability of the images produced by our novel model.
Utilizing a novel model for ONSD ultrasonography, we have determined the intraoperator reliability of ONSD measurement to be moderate, with no appreciable difference amongst multiple operators. Improvement in measurement reliability has been demonstrated between expert and novice operators with our model, indicating the potential benefit of simulation platforms for teaching the technique of ONSD ultrasound.
It has been shown that metal ion implantation can harden single crystal sapphire and introduce compressive stresses at the surface, which may lead to an increase in the fracture toughness of the material. This may significantly affect the usefulness of this material as a shatter-resistant optical window in missile applications. In this study, we have examined the extent to which sapphire can be implanted without severely degrading its optical quality by ion beam defect production. Optically-polished single-crystal c-axis sapphire was implanted with 150 keV Cr+, Ti+, and Si+ ions to doses of 0.3 – 3.0 × 1017 ions/cm2 at both room temperature and at 800 °C, to measure the optical effect of in situ annealing. Rutherford backscattering spectrometry showed evidence of implant species migration only in the case of Ti implanted at high temperatures; all other implant profiles were Gaussian. The optical transmittance of the sapphire was examined using visible spectrum transmission and Fourier Transform Infrared Spectroscopy. Si implantation resulted in a 10 % reduction in infrared transmittance at the highest ion dose, but this was reduced to 6 % when the implantation was done at high temperature. Both Cr and Ti implantation reduced the sapphire IR transmittance (by 16 % and 42 %, respectively) , but the effect of implantation temperature on transmittance was different. High temperature during implantation increased the transmittance of Cr-implanted samples, but further darkened Ti-implanted samples. Photon tunneling and atomic force microscopy showed that both Ti and Cr implantation roughened the surface of the material.
Surface processing of microelectronic materials by bombardment with nanoparticles of condensed gases (i.e., clusters) in the form of an ion beam, makes possible etching and smoothing of those surfaces to very high figures of merit. As this is not possible with any conventional ion method, gas-cluster ion-beam systems have great potential in manufacturing. The formation of gas clusters and their collision with surfaces provides an interesting arena for novel physics and surface science. This paper outlines a physical model for the clusters and surface interactions, and provides examples of surface processing. In particular, the reduction of surface roughness while etching by cluster-ion bombardment is illustrated for various materials utilized in microelectronics.
Polycrystalline Si (poly-Si) waveguides offer design flexibility and multilayered structures in Si-integrated photonic devices. However, as-deposited poly-Si surfaces are rough compared with single-crystalline Si, and a rough surface causes significant waveguide scattering loss at the surface. In this study, surface smoothing of poly-Si waveguides with a gas-cluster ion beam (GCIB) was demonstrated as a new smoothing technique. As the GCIB process is a directional ion-beam process, in principle it can be applied not only to plane surfaces but also to three-dimensional or non-flat structures, such as waveguide ridges.
The initial average roughness of as-deposited poly-Si films (625°C, 1 μm thick) ranged from 15 nm to 22 nm, and the grain sizes were distributed from 0.2 to 0.4μm. This rough surface was dramatically smoothed to a roughness of 1.5 nm by Ar cluster ion irradiation. From the relation between the sputtered depth and the surface roughness, the sputtered depth must be greater than the height difference of the roughness (peak-to-valley) to obtain smooth surfaces. Optical transmission losses at λ =1.54 μm were measured using cutback measurement from samples before and after the smoothing by GCIB. After surface smoothing with GCIB, the optical loss decreased from 85 dB/cm to 54 dB/cm.
Local structures of high surface area sodium titanate materials have been examined as a function of pH using solid state 17O nuclear magnetic resonance (NMR) spectroscopy. Using 17O NMR, it is possible to determine the relative populations of nonbridging oxygens as well as oxygens bridging between two, three, and four titanium atoms. Results show that protonation of ion exchange sites in titanate materials is not a simple ion exchange process but involves a repolymerization and restructuring of the titanate network. The observed structural changes are consistent with reported phase stabilities of titanates in water as well as with known hydrolysis and condensation reactions.
An unprecedented total of 190 holo-epiphytic and five hemi-epiphytic vascular plant species were collected from the canopy and the trunk of a single strangler fig (Ficus crassiuscula) in a Peruvian montane cloud forest. A large majority of the vascular species were rare in occurrence, suggesting a high proportion of patchily distributed species within the cloud forest. One hundred and fourteen of the vascular epiphyte species were orchids, 37 species were ferns, and 17 species were bromeliads. Seventy-three of the orchid species belonged to the Pleurothallidinae. Perú is one of the global strongholds of remaining unmodified tropical montane cloud forest. However, cloud forest studies on any topic emanating from Perú are relatively rare. The outstanding epiphyte species richness of a single tree highlights both the importance of cloud forests for global biodiversity, and the urgency for more research and conservation initiatives within the cloud forests of Perú.
Peruvian montane cloud forests are one of the global strongholds of remaining unmodified tropical montane cloud forest (Mulligan, this volume). However, they have received comparatively little scientific attention until now (e.g. Frahm, 1987: Leo, 1995; Weng et al. 2004; Gomez-Peralta et al., 2008) and are under increasing threat of deforestation (Young and León, 1995; Mulligan, this volume). The extinction rate of plant species through cloud forest removal in Perú is unknown because most cloud forests have not been botanically prospected (Honorio and Reynel, 2004). Epiphyte flora makes up a large component of plant diversity in Andean forests (Gentry and Dodson, 1987a; Kelly et al., 1994; Bussmann, 2001; Nieder et al., 2001, cf. Gradstein et al., this volume; Krömer and Gradstein, this volume).
The serious problem presented by the high prevalence of severe pulmonary tuberculosis in early adult life in the Highlands and Islands of Scotland is exemplified by the figures in the following table, for which we are indebted to the Department of Health and the Registrar-General for Scotland.
Searches in Clusters, Stellar Associations and the Field
J. Liebert, Steward Observatory, University of Arizona, Tucson, AZ 85721, USA,
I. N. Reid, California Institute of Technology, 105-24, Pasadena, CA 91125, USA,
J. D. Kirkpatrick, IPAC, Caltech 100-24, Pasadena, CA 91125, USA,
R. Cutri, IPAC, Caltech 100-24, Pasadena, CA 91125, USA,
B. Nelson, IPAC, Caltech 100-24, Pasadena, CA 91125, USA,
D. G. Monet, U.S. Naval observatory, P.O. Box 1149, Flagstaff AZ 86002, USA,
C. C. Dahn, U.S. Naval observatory, P.O. Box 1149, Flagstaff AZ 86002, USA,
M. Skrutskie, University of Massachusetts, Amherst MA 01003, USA,
J. E. Gizis, University of Massachusetts, Amherst MA 01003, USA,
M. D. Fisher, Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
The initiation of the DENIS and 2MASS surveys are resulting in the discoveries of dozens of field brown dwarf candidates, and the need to develop a new spectral class of L dwarfs. The L dwarfs are perhaps only a few hundred degrees cooler than the latest M dwarfs (M9–9.5 V), and are many hundreds of degrees warmer than the brown dwarf Gliese 229B. However, the formation of dust removes TiO and VO from the atmospheres, resulting in qualitatively different red spectra, with for example a strong, pressure-broadened K I resonance doublet. In contrast, the infrared spectra show the same (H2O and CO) molecular features as in late M dwarfs, with no evidence of methane. The detection of the Li I 6707 Å resonance doublet shows that many L dwarfs, at least, have substellar masses. Based on analysis of point sources from the first 1% of sky, well over 1,000 L dwarfs should be detected in the 2MASS survey. Our results suggest that several might exist within 5 pc of the Sun.
After waiting three decades since Kumar (1963) proposed their existence, we are gratified to see literally dozens of candidates probably or definitely below the stellar mass limit being found in young clusters and associations. Here one has the big advantages that the age, the distance and luminosity of a cluster member are generally known. In this presentation, complementary to the topic of this meeting, we report the finding of a large number of candidates in one of the first infrared surveys of the field population.