Reducibility of Ce1-xZrxO2: origin of enhanced oxygen storage capacity

We combine first-principles calculations with EXAFS studies to investigate the origin of high oxygen storage capacity in ceria-zirconia solid solution, prepared by solution combustion method. We find that nanocrystalline Ce0.5Zr0.5O2 can be reduced to Ce0.5Zr0.5O1.57 by H-2 upto 850 degrees C with an OSC of 65 cc/gm which is extremely high. Calculated local atomic-scale structure reveals the presence of long and short bonds resulting in four-fold coordination of the cations, confirmed by the EXAFS studies. Bond valence analysis of the microscopic structure and energetics is used to evaluate the strength of binding of different oxide ions and vacancies. We find the presence of strongly and weakly bound oxygens, of which the latter are responsible for the higher oxygen storage capacity in the mixed oxides than in the pure CeO2.

Functional limitations and quality of life in schizophrenia and other psychotic disorders

There is substantial evidence of the decreased functional capacity, especially everyday functioning, of people with psychotic disorder in clinical settings, but little research about it in the general population. The aim of the present study was to provide information on the magnitude of functional capacity problems in persons with psychotic disorder compared with the general population. It estimated the prevalence and severity of limitations in vision, mobility, everyday functioning and quality of life of persons with psychotic disorder in the Finnish population and determined the factors affecting them. This study is based on the Health 2000 Survey, which is a nationally representative survey of 8028 Finns aged 30 and older. The psychotic diagnoses of the participants were assessed in the Psychoses of Finland survey, a substudy of Health 2000. The everyday functioning of people with schizophrenia is studied widely, but one important factor, mobility has been neglected. Persons with schizophrenia and other non-affective psychotic disorders, but not affective psychoses had a significantly increased risk of having both self-reported and test-based mobility limitations as well as weak handgrip strength. Schizophrenia was associated independently with mobility limitations even after controlling for lifestyle-related factors and chronic medical conditions. Another significant factor associated with problems in everyday functioning in participants with schizophrenia was reduced visual acuity. Their vision was examined significantly less often during the five years before the visual acuity measurement than the general population. In general, persons with schizophrenia and other non-affective psychotic disorder had significantly more limitations in everyday functioning, deficits in verbal fluency and in memory than the general population. More severe negative symptoms, depression, older age, verbal memory deficits, worse expressive speech and reduced distance vision were associated with limitations in everyday functioning. Of all the psychotic disorders, schizoaffective disorder was associated with the largest losses of quality of life, and bipolar I disorder with equal or smaller losses than schizophrenia. However, the subjective loss of qualify of life associated with psychotic disorders may be smaller than objective disability, which warrants attention. Depressive symptoms were the most important determinant of poor quality of life in all psychotic disorders. In conclusion, subjects with psychotic disorders need regular somatic health monitoring. Also, health care workers should evaluate the overall quality of life and depression of subjects with psychotic disorders in order to provide them with the basic necessities of life.

Molecular phylogeny of Hemidactylus geckos (Squamata: Gekkonidae) of the Indian subcontinent reveals a unique Indian radiation and an Indian origin of Asian house geckos

Represented by approximately 85 species, Hemidactylus is one of the most diverse and widely distributed genera of reptiles in the world. In the Indian subcontinent, this genus is represented by 28 species out of which at least 13 are endemic to this region. Here, we report the phylogeny of the Indian Hemidactylus geckos based on mitochondrial and nuclear DNA markers sequenced from multiple individuals of widely distributed as well as endemic congeners of India. Results indicate that a majority of the species distributed in India form a distinct clade whose members are largely confined to the Indian subcontinent thus representing a unique Indian radiation. The remaining Hemidactylus geckos of India belong to two other geographical clades representing the Southeast Asian and West-Asian arid zone species. Additionally, the three widely distributed, commensal species (H. brookii, H. frenatus and H. flaviviridis) are nested within the Indian radiation suggesting their Indian origin. Dispersal-vicariance analysis also supports their Indian origin and subsequent dispersal out-of-India into West-Asian arid zone and Southeast Asia. Thus, Indian subcontinent has served as an important arena for diversification amongst the Hemidactylus geckos and in the evolution and spread of its commensal geckos. (C) 2010 Elsevier Inc. All rights reserved.

Origin of the plateau in the low-temperature thermal conductivity of silica

Thermal conductivities of glasses at low temperatures show strikingly similar behavior irrespective of their chemical composition. While for T<1 K the thermal conductivity can be understood in the phenomenological tunneling model; the ‘‘universal plateau’’ in the temperature interval 15>T>2 K is totally unexplained. While Rayleigh scattering of phonons by structural disorder should be the natural cause for limiting the mean free path of phonons in this temperature range, it has been concluded before that in glasses a strong enough source of such scattering does not exist. In this study we show by a proper structural analysis in at least one material (namely, silica) that a strong enough source of Rayleigh scattering of phonons in glasses does exist so that the ‘‘universal plateau’’ can be explained without invoking any new mechanism. This may be for the first time that the low-temperature property of a structural glass has been correlated to its structure.

Origin of nonmetallicity in PrBa2Cu3O7 from a study of Gd1−xPrxBa2Cu3O7 using soft x-ray absorption at the oxygen K-edge

We present the x-ray absorption data at the oxygen K-edge using total yield technique for Gd1−xPrxba2Cu3O7 (x= 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0). The data clearly to oxygen that the holes doped in the GdBa2Cu3O7 due to oxygen composition are not removed by Pr doping even for the x = 1.0 sample, suggesting that Pr is predominantly in the formally trivalent state. However, the data also clearly indicate the evidence of hybridization effects between the Pr3+ and the adjacent CuO2 layers. This is suggested to be responsible for the progressive suppression of Tc and the metallicity with Pr doping in these systems.

Functional outcome and health-related quality of life after traumatic brain injury in the framework of the International Classification of Functioning, Disability and Health (ICF)

Traumatic brain injury (TBI) affects people of all ages and is a cause of long-term disability. In recent years, the epidemiological patterns of TBI have been changing. TBI is a heterogeneous disorder with different forms of presentation and highly individual outcome regarding functioning and health-related quality of life (HRQoL). The meaning of disability differs from person to person based on the individual s personality, value system, past experience, and the purpose he or she sees in life. Understanding of all these viewpoints is needed in comprehensive rehabilitation. This study examines the epidemiology of TBI in Finland as well as functioning and HRQoL after TBI, and compares the subjective and objective assessments of outcome. The frame of reference is the International Classification of Functioning, Disability and Health (ICF). The subjects of Study I represent the population of Finnish TBI patients who experienced their first TBI between 1991 and 2005. The 55 Finnish subjects of Studies II and IV participated in the first wave of the international Quality of life after brain injury (QOLIBRI) validation study. The 795 subjects from six language areas of Study III formed the second wave of the QOLIBRI validation study. The average annual incidence of Finnish hospitalised TBI patients during the years 1991-2005 was 101:100 000 in patients who had TBI as the primary diagnosis and did not have a previous TBI in their medical history. Males (59.2%) were at considerably higher risk of getting a TBI than females. The most common external cause of the injury was falls in all age groups. The number of TBI patients ≥ 70 years of age increased by 59.4% while the number of inhabitants older than 70 years increased by 30.3% in the population of Finland during the same time period. The functioning of a sample of 55 persons with TBI was assessed by extracting information from the patients medical documents using the ICF checklist. The most common problems were found in the ICF components of Body Functions (b) and Activities and Participation (d). HRQoL was assessed with the QOLIBRI which showed the highest level of satisfaction on the Emotions, Physical Problems and Daily Life and Autonomy scales. The highest scores were obtained by the youngest participants and participants living independently without the help of other people, and by people who were working. The relationship between the functional outcome and HRQoL was not straightforward. The procedure of linking the QOLIBRI and the GOSE to the ICF showed that these two outcome measures cover the relevant domains of TBI patients functioning. The QOLIBRI provides the patients subjective view, while the GOSE summarises the objective elements of functioning. Our study indicates that there are certain domains of functioning that are not traditionally sufficiently documented but are important for the HRQoL of persons with TBI. This was the finding especially in the domains of interpersonal relationships, social and leisure activities, self, and the environment. Rehabilitation aims to optimize functioning and to minimize the experience of disability among people with health conditions, and it needs to be based on a comprehensive understanding of human functioning. As an integrative model, the ICF may serve as a frame of reference in achieving such an understanding.

A possible origin of viscosity in Keplerian accretion disks due to secondary perturbation: Turbulent transport without magnetic fields

The origin of hydrodynamic turbulence in rotating shear flow is a long standing puzzle. Resolving it is especially important in astrophysics when the flow's angular momentum profile is Keplerian which forms an accretion disk having negligible molecular viscosity. Hence, any viscosity in such systems must be due to turbulence, arguably governed by magnetorotational instability, especially when temperature T greater than or similar to 10(5). However, such disks around quiescent cataclysmic variables, protoplanetary and star-forming disks, and the outer regions of disks in active galactic nuclei are practically neutral in charge because of their low temperature, and thus are not expected to be coupled with magnetic fields enough to generate any transport due to the magnetorotational instability. This flow is similar to plane Couette flow including the Coriolis force, at least locally. What drives their turbulence and then transport, when such flows do not exhibit any unstable mode under linear hydrodynamic perturbation? We demonstrate that the three-dimensional secondary disturbance to the primarily perturbed flow that triggers elliptical instability may generate significant turbulent viscosity in the range 0.0001 less than or similar to nu(t) less than or similar to 0.1, which can explain transport in accretion flows.

Origin of the insulating state in NaCuO2

We study the electronic structure of NaCuO2 by analysing experimental core level photoemission and X-ray absorption spectra using a cluster as well as an Anderson impurity Hamiltonian including the band structure of the oxygen sublattice. We show that the X-ray absorption results unambiguously establish a negative value of the charge transfer energy, A. Further, mean-field calculations for the edge-shared one-dimensional CuO2 lattice of NaCuO2 within the multiband Hubbard Hamiltonian show that the origin of the insulating nature lies in the band structure rather than in the correlation effects. LMTO-ASA band structure calculations suggest that NaCuO2 is an insulator with a gap of around 1 eV.

Origin of visible photoluminescence from porous silicon as studied by Raman spectroscopy

In this paper we discuss the different models proposed to explain the visible luminescence in porous silicon (PS). We review our recent photoluminescence and Raman studies on PS as a function of different preparation conditions and isochronal thermal annealing. Our results can be explained by a hybrid model which incorporates both nanostructures for quantum confinement and silicon complexes (such as SiHx, and siloxene) and defects at Si/SiO2, interfaces as luminescent centres.

Origin of magnetism and trend in T-c in Cr-based double perovskites: Interplay of two driving mechanisms

Hamiltonian constructed in a first principles manner, we explored the origin of magnetism and the T-c trend in Cr-based double perovskite series, Sr2CrB'O-6 (B' = W/Re/Os). Our study shows that the apparently puzzling T-c trend in Sr2CrB'O-6 (B' = W/Re/Os) series can be understood in terms of the interplay of the hybridization driven mechanism and the superexchange mechanism.

Microscopic origin of the chirality driven morphologies of the amphiphilic monolayers and bilayers

It is widely known that the compressed monolayers and bilayers of chiral lipids or fatty acids form helical morphologies, while the corresponding racemic modification gives only flat platelets without twist. No molecular explanation of this phenomenon is yet available, although subtle interactions at the chiral centers have often been proposed as the driving force behind the morphology of the aggregate to form a particular shape. In the present study, the morphologies of the chiral amphiphilic assemblies have been predicted on the basis of an effective pair potential between the molecules, which depends on the relative sizes of the groups attached to the chiral centers, the orientation of the amphiphilic molecules and also on the distance between them. It is shown that fur a pair of same kind of enantiomers, the minimum energy conformation favours a twist angle between them. This twist between the neighbouring molecules gives rise to the helicity of the aggregate. The present theory also shows from the molecular considerations that for a pair of mirror-image isomers (i.e. the racemic modification) the minimum energy conformation corresponds to the zero angle between the molecules, thus giving rise to flat platelets as observed in experiments. Another fascinating aspect of such chirality driven helical structures is that the sense (or the handedness) of the helix is highly specific about the chirality of the monomer concerned. The molecular theory shows, for the first time, that the sense of the helical structures in many cases is determined by the sizes of the groups attached to the chiral centers and the effective potential between them. The predicted senses of the helical structures are in complete agreement with the experimental results.

Origin of a trend in ECMWF wind analysis and its objective removal

The suitability of the European Centre for Medium Range Weather Forecasting (ECMWF) operational wind analysis for the period 1980-1991 for studying interannual variability is examined. The changes in the model and the analysis procedure are shown to give rise to a systematic and significant trend in the large scale circulation features. A new method of removing the systematic errors at all levels is presented using multivariate EOF analysis. Objectively detrended analysis of the three-dimensional wind field agrees well with independent Florida State University (FSU) wind analysis at the surface. It is shown that the interannual variations in the detrended surface analysis agree well in amplitude as well as spatial patterns with those of the FSU analysis. Therefore, the detrended analyses at other levels as well are expected to be useful for studies of variability and predictability at interannual time scales. It is demonstrated that this trend in the wind field is due to the shift in the climatologies from the period 1980-1985 to the period 1986-1991.