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.
Abnormal effort-based decision-making represents a potential mechanism underlying motivational deficits (amotivation) in psychotic disorders. Previous research identified effort allocation impairment in chronic schizophrenia and focused mostly on physical effort modality. No study has investigated cognitive effort allocation in first-episode psychosis (FEP).
Cognitive effort allocation was examined in 40 FEP patients and 44 demographically-matched healthy controls, using Cognitive Effort-Discounting (COGED) paradigm which quantified participants’ willingness to expend cognitive effort in terms of explicit, continuous discounting of monetary rewards based on parametrically-varied cognitive demands (levels N of N-back task). Relationship between reward-discounting and amotivation was investigated. Group differences in reward-magnitude and effort-cost sensitivity, and differential associations of these sensitivity indices with amotivation were explored.
Patients displayed significantly greater reward-discounting than controls. In particular, such discounting was most pronounced in patients with high levels of amotivation even when N-back performance and reward base amount were taken into consideration. Moreover, patients exhibited reduced reward-benefit sensitivity and effort-cost sensitivity relative to controls, and that decreased sensitivity to reward-benefit but not effort-cost was correlated with diminished motivation. Reward-discounting and sensitivity indices were generally unrelated to other symptom dimensions, antipsychotic dose and cognitive deficits.
This study provides the first evidence of cognitive effort-based decision-making impairment in FEP, and indicates that decreased effort expenditure is associated with amotivation. Our findings further suggest that abnormal effort allocation and amotivation might primarily be related to blunted reward valuation. Prospective research is required to clarify the utility of effort-based measures in predicting amotivation and functional outcome in FEP.
Febrile seizure (FS) in children is a common complication of infections with respiratory viruses and hand, foot and mouth disease (HFMD). We conducted a retrospective ecological time-series analysis to determine the temporal relationship between hospital attendances for FS and HFMD or respiratory virus infections. Epilepsy attendance was used as a control. Data from 2004 to 2012 FS and epilepsy hospital attendance, HFMD notifications to the Ministry of Health and from laboratory-confirmed viral respiratory infections among KK Women's and Children's Hospital inpatients were used. A multivariate linear regression analysis was conducted to evaluate the relationship between FS and the virus time series. Relative risks of FS by age were calculated using Bayesian statistical methods. Paediatric accident and emergency (A&E) attendances for FS were found to be associated with influenza A (extra 0.47 FS per influenza A case), B (extra 0.32 per influenza B case) and parainfluenza 3 (extra 0.35 per parainfluenza type 3 case). However, other viruses were not significantly associated with FS. None of the viruses were associated with epileptic seizure attendance. Influenza A, B and parainfluenza 3 viruses contributed to the burden of FS resulting in A&E attendance. Children at risk of FS should be advised to receive seasonal influenza vaccination.
Nanoscale superlattice-like (SLL) dielectric was employed to reduce the power consumption of the Phase-change random access memory (PCRAM) cells. In this study, we have simulated and found that the cells with the SLL dielectric have a higher peak temperature compared to that of the cells with the SiO2 dielectric after constant pulse activation, due to the interface scattering mechanism. Scaling of the SLL dielectric has resulted in higher peak temperatures, which can be even higher after material/structural modifications. Furthermore, the SLL dielectric has good material properties that enable the cells to have high endurance. This shows the effectiveness of the SLL dielectric for advanced memory applications.
Epilepsy can be caused by vaccination as a leading symptom of vaccine-induced encephalopathy and febrile seizures can also occur as a result of vaccine-induced fever. Pertussis vaccination is a highly effective means to prevent a disabling and sometimes deadly disease. The live vaccines and the vaccines prepared from infective neural tissue are perhaps the vaccines that carry the greatest risk. The cellular vaccines, and also vaccines with high levels of endotoxin, are said to be generally less safe than the acellular vaccines although evidence on these points is weak especially where seizures are a rare side effect, largely because of the absence of sufficiently powered comparisons. The risks also probably vary according to manufacturer and to the quantity and type of adjuvant which further complicates assessment. Case reports exist of epilepsy, autism, and cerebral palsy developing after measles, mumps, rubella (MMR) and measles vaccines.
In Southeast Asian tropical rainforests, two events, severe droughts associated with the El Niño-Southern Oscillation and general flowering, a type of community-wide mass flowering, occur at irregular, supra-annual intervals. The relationship between these two supra-annual events and patterns of insect population fluctuations has yet to be clearly elucidated. Leaf beetles (Chrysomelidae) are major herbivores and flower-visitors of canopy trees, affecting their growth and reproduction and, in turn, affected by tree phenology; but their population fluctuations in the Southeast Asian tropics have not been extensively investigated. We examined population fluctuation patterns of the 34 most dominant chrysomelid species in relation to the two supra-annual events by conducting monthly light-trapping over seven years in a lowland dipterocarp forest in Borneo. Our results showed large community variation in population fluctuation patterns and a supra-annual (between-year) variation in abundance for most of the dominant chrysomelids that was significantly larger than the annual (within-year) variation. Specifically, in response to a severe drought in 1998, chrysomelid species exhibited different population responses. These results show that population fluctuations of individual species, rather than the entire assemblage, must be analyzed to determine the effects of changes in environmental conditions on the structure of insect assemblages in the tropics, especially in regions where supra-annual environmental changes are relatively more important than seasonal changes.
Nathalie A. Cabrol, Space Science Division, MS 245-3, NASA Ames Research Center, California,
Chris P. McKay, Space Science Division, MS 245-3, NASA Ames Research Center, California,
Edmond A. Grin, Space Science Division, MS 245-3, NASA Ames Research Center, California,
Keve T. Kiss, Hungarian Danube Research Station, Institute of Ecology and Botany, Hungarian Academy of Sciences, Göd,
Era Ács, Hungarian Danube Research Station, Institute of Ecology and Botany, Hungarian Academy of Sciences, Göd,
Balint Tóth, Hungarian Danube Research Station, Institute of Ecology and Botany, Hungarian Academy of Sciences, Göd,
Istran Grigorszky, Debrecen University, Botanical Department, Debrecen,
K. Szabò, Eötvös L. University, Microbiological Department, Budapest,
David A. Fike, Eötvös L. University, Microbiological Department, Budapest,
Andrew N. Hock, University of California, Los Angeles,
Cecilia Demergasso, Laboratorio de Microbiología Técnica, Avda,
Lorena Escudero, Laboratorio de Microbiología Técnica, Avda,
P. Galleguillos, Laboratorio de Microbiología Técnica, Avda,
Guillermo Chong, Departamento de Geología, Universidad Católica del Norte, Avda,
Brian H. Grigsby, Schreder Planetarium/ARISE, Redding,
Jebner Zambrana Román, Servicio Nacional de Geología y Minería (SERGEOMIN), La Paz,
Cristian Tambley, Department of Astrophysics, Avda
A series of astrobiological high-altitude expeditions to the South American Andean Mountains were initiated in 2002 to explore the highest perennial lakes on Earth, including several volcanic crater lakes at or above 6000 m in elevation. During the next five years, they will provide the first integrated long-term astrobiological characterization and monitoring of lacustrine environments and their biology at such an altitude. These extreme lakes are natural laboratories that provide the field data, currently missing above 4000 m, to complete our understanding of terrestrial lakes and biota. Research is being performed on the effects of UV in low-altitude lakes and models of UV flux over time have been developed (Cockell, 2000). The lakes showing a high content of dissolved organic material (DOM) shield organisms from UV effects (McKenzie et al., 1999; Rae et al., 2000). DOM acts as a natural sunscreen by influencing water transparency, and therefore is a determinant of photic zone depth (Reche et al., 2000). In sparsely vegetated alpine areas, lakes tend to be clearer and offer less protection from UV to organisms living in the water. Transparent water, combined with high UV irradiance may maximize the penetration and effect of UV radiation as shown for organisms in alpine lakes (e.g., Vincent et al., 1984; Vinebrook and Leavitt, 1996). Shallow-water benthic communities in these lakes are particularly sensitive to UV radiation. Periphyton, which defines communities of microorganisms in bodies of water, can live on various susbtrates.
The growth temperature and properties of Ge4Sb3Te3 thin films are presented in this paper. The critical growth temperature of Ge4Sb3Te3 is between 300 and 340 °C. The Ge4Sb3Te3 films can only be grown on a substrate below the critical growth temperature. The typical resistivity and carrier density are in the order of 10-4 Ωcm and 1021 cm-3 for crystalline phase. It has a rock salt crystal structure with a lattice constant of 0.602 nm. Ge4Sb3Te3 has a better thermal stability but a lower crystallization speed than Ge2Sb2Te5.
In this paper, a three-dimensional finite-element modeling is performed for the analyses of Chalcogenide Random Access Memory (C-RAM), a non-rotation nonvolatile phase change memory cell. The thermal effect generated by an incident electric pulse was mainly discussed. Thermal performances of the cell as a result of electrical and geometrical variations were quantified. Current density distribution, temperature profiles, temperature history, heating rate, cooling rate, and heat flow characteristics were obtained and analyzed. The study is useful for the failure analysis of the C-RAM.
A solid polythiophene pellet was ablated by a KrF excimer laser beam to deposit thin films on silicon substrates. The laser-ablated plasma was studied by optical emission spectroscopy to identify the photon-breaking of C–S bonds in the ablated heterocycles. Raman and x-ray photoelectron spectroscopy measurements of the deposited thin films also supported the selective photon-induced bond breaking. After eliminating sulfur in the molecular structures, the thin films appeared to be composed of cubic nanocrystals with a uniform size of 240 nm. X-ray diffraction measurement determined the cubic crystal structures with a lattice constant of α =3.38 Å and suggested a quasi-onedimensional carbon chain structure along the body diagonal of the cube.
Laser directly writing of nanostrucrures on magnetic film surfaces with optical near field effects has been investigated. Spherical 0.99 m or 0.47 m silica particles were placed on Cr/CoCrPt multilayers. After laser illumination with an excimer laser for a single shot, pits were obtained at the original position of the particles using different laser fluences or particle size parameters. The mechanism of the formation of nanostructure pattern was discussed and found to be the near-field optical resonance effect induced by particles on the surface. A comparison with accurate theoretical calculations of near-field light intensity distribution showed good agreement with the experiment results. The method of particle enhanced laser irradiation allows the study of field enhancement effects as well as its potential applications for nanolithography.
Thin films of polythiophene, a kind of polyheterocyclic compound with hydrogen function groups, were deposited by KrF excimer laser ablation of a compressed solid target in a vacuum chamber. The laser pulse fluence was approximately selected at 2 J/cm2 with a pulse duration of 25 ns. The structural, topographic, and electronic properties of the deposited thin films were analyzed by atomic force microscope, x-ray diffraction, and Raman and infrared spectroscopy measurements. Deposited thin films were observed to have good crystal properties and to be composed of crystalline cubes with a uniform size of 0.1 μm. The electronic structure of the deposited thin films should be different from the target materials, resulting from the laser irradiation effects. The influence of the deposition temperature on the structural and electronic properties of the deposited thin films was studied.
The structural evolution of GaN films during the initial growth process of metalorganic chemical vapor deposition (MOCVD) - low temperature nucleation layer growth, annealing, and high temperature epitaxial growth - was investigated in a synchrotron x-ray scattering experiment. The nucleation layer grown at 560°C that was predominantly cubic GaN consisted of tensile-strained aligned domains and relaxed misaligned domains. The hexagonal GaN, transformed from the cubic GaN during annealing to 1100°C, showed disordered stacking. The atomic layer spacing decreased as the fraction of the hexagonal domains increased. Subsequent growth of epitaxial GaN at 1100°C resulted in the formation of ordered hexagonal GaN domains with rather broad mosaicity.