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 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.
The St. Louis aerosol was sampled during the period 16-22 August 1973 simultaneously at two locations using cascade impactors for sequential 12-hour samples. The six particle size fractions of each sampling were individually analyzed using PIXE for elements from S to Br and beyond and for heavy elements including Pb which permitted time variations of concentrations and particle size distributions to be followed and related to meteorological changes during the sampling period. In addition, the data were compared with average levels of the elements in coastal north Florida and maritime Bermuda as well as at a third St. Louis site. From this it appeared that some of the concentrations in St. Louis were at natural levels whereas others appeared to be higher and linked to air pollution sources. These relationships and others in this study may lead to criteria for distinguishing between pollutants and natural background in urban aerosols.
A global array of 20 radio observatories was used to measure the three-dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the Venus atmosphere by the VEGA spacecraft.
Childhood trauma increases risk of a range of mental disorders including psychosis. Whereas the mechanisms are unclear, previous evidence has implicated atypical processing of emotions among the core cognitive models, in particular suggesting altered attentional allocation towards negative stimuli and increased negativity bias. Here, we tested the association between childhood trauma and brain activation during emotional face processing in patients diagnosed with psychosis continuum disorders. In particular, we tested if childhood trauma was associated with the differentiation in brain responses between negative and positive face stimuli. We also tested if trauma was associated with emotional ratings of negative and positive faces.
We included 101 patients with a Diagnostic and Statistical Manual of Mental Disorders (DSM) schizophrenia spectrum or bipolar spectrum diagnosis. History of childhood trauma was obtained using the Childhood Trauma Questionnaire. Brain activation was measured with functional magnetic resonance imaging during presentation of faces with negative or positive emotional expressions. After the scanner session, patients performed emotional ratings of the same faces.
Higher levels of total childhood trauma were associated with stronger differentiation in brain responses to negative compared with positive faces in clusters comprising the right angular gyrus, supramarginal gyrus, middle temporal gyrus and the lateral occipital cortex (Cohen's d = 0.72–0.77). In patients with schizophrenia, childhood trauma was associated with reporting negative faces as more negative, and positive faces as less positive (Cohen's d > 0.8).
Along with the observed negativity bias in the assessment of emotional valence of faces, our data suggest stronger differentiation in brain responses between negative and positive faces with higher levels of trauma.
Fibre Reinforced Polymer (FRP) is becoming a valid alternative to many traditional heavy metal industries because of its high specific stiffness over the more classical construction metals. Recent trend of more complex geometry of composites is causing increasing difficulty in composite manufacturing. A method to optimize the manufacturing process is thus imposed to ensure and improve the quality of manufactured parts. Because of the irregular 3D shapes of the composites, traditional flat sensor system is becoming unfavorable and nonpractical for monitoring purpose. In this work, the current development status of a deformable microsystem for in situ cure degree monitoring of a glass fibre reinforced plastic is presented. To accommodate the non-flat shape of the composites, the proposal is to interconnect non-deformable functional island, which contains the capacitive sensor for cure degree monitoring, with meander-shaped deformable interconnections. The developed sensor system is able to withstand the manufacturing process where change of pressure and internal strain, thus force exerted on the sensor system, is involved.
We determined the association between neighborhood socio-environmental factors and insomnia symptoms in a nationally representative sample of US adults aged >50 years.
Data were analyzed from two waves (2006 and 2010) of the Health and Retirement Study using 7,231 community-dwelling participants (3,054 men and 4,177 women) in the United States. Primary predictors were neighborhood physical disorder (e.g. vandalism/graffiti, feeling safe alone after dark, and cleanliness) and social cohesion (e.g. friendliness of people, availability of help when needed, etc.); outcomes were insomnia symptoms (trouble falling asleep, night awakenings, waking too early, and feeling unrested).
After adjustment for age, income, race, education, sex, chronic diseases, body mass index, depressive symptoms, smoking, and alcohol consumption, each one-unit increase in neighborhood physical disorder was associated with a greater odds of trouble falling asleep (odds ratio (OR) = 1.09, 95% confidence interval (CI): 1.04–1.14), waking too early (OR = 1.05, 95% CI: 1.00–1.10), and, in adults aged ≥69 years (adjusting for all variables above except age), feeling unrested in the morning (OR = 1.11, 95% CI: 1.02–1.22 in 2006). Each one-unit increase in lower social cohesion was associated with a greater odds of trouble falling asleep (OR = 1.06, 95% CI: 1.01–1.11) and feeling unrested (OR = 1.09, 95% CI: 1.04–1.15).
Neighborhood-level factors of physical disorder and social cohesion are associated with insomnia symptoms in middle-aged and older adults. Neighborhood-level factors may affect sleep, and consequently health, in our aging population.
The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.
Let Ω⊂ℝN be a smooth bounded domain and let f⁄≡0 be a possibly discontinuous and unbounded function. We give a necessary and sufficient condition on f for the existence of positive solutions for all λ>0 of Dirichlet periodic parabolic problems of the form Lu=h(x,t,u)+λf(x,t), where h is a nonnegative Carathéodory function that is sublinear at infinity. When this condition is not fulfilled, under some additional assumptions on h we characterize the set of λs for which the aforementioned problem possesses some positive solution. All results remain true for the corresponding elliptic problems.
High-resolution Hα velocity fields provide important observational constraints on the dark matter distribution in dwarf and low surface brightness galaxies. These two-dimensional data show that dark matter-dominated galaxies tend to be more consistent with cored halos than cuspy halos, at odds with theoretical expectations. Using N-body/SPH simulations of disk galaxy formation in cuspy spherical and triaxial dark matter halos, as well as cored dark matter halos, we “observe” the simulated galaxies under a variety of realistic observing conditions. We use these mock IFU velocity field observations to determine how well the underlying dark matter halo can be recovered and to test the hypothesis that cusps can be obscured by triaxial dark matter halos.
A cross-sectional study was conducted in participants with schizophrenia to explore a potential association between the patients' remission status and neurocognitive functioning and to examine whether these factors have an impact on functional outcome.
Psychopathological symptoms were rated by means of the Positive and Negative Syndrome Scale with symptom remission being assessed by applying the severity component of the recently proposed remission criteria. Tests for the cognitive battery were selected to cover domains known to be impaired in patients with schizophrenia. Next to pre-morbid intelligence, attention performance, executive functioning, verbal fluency, verbal learning and memory, working memory and visual memory were assessed. The joint effect of remission status and neurocognitive functioning on treatment outcome was investigated by logistic regression analysis.
Out of 140 patients included in the study, 62 were symptomatically remitted. Mean age, education and sex distribution were comparable in remitted and non-remitted patients. Remitted patients showed significantly higher values on tests of verbal fluency, alertness and optical vigilance. Both symptomatic remission as well as performance on tests of working memory and verbal memory had a significant effect on the patients' employment status.
In the present study neuropsychological measures of frontal lobe functioning were associated with symptomatic remission from schizophrenia. In addition, both symptomatic remission and performance on tests of working memory and verbal memory had a significant effect on the patients' employment status. Longitudinal follow-up data are needed to determine how the associations of these determinants of functional outcome interact and change over time.
The influence of iron on the the microstructure and properties of B2 NiAl has been investigated using electrical resistivity, magnetic susceptibility, microhardness and transmission electron microscopy. The resistivity data suggest that quenched-in vacancies (1) enhance iron rearrangement at low temperatures (600–800 K) and (2) annihilate above 800 K. These effects depend strongly on Ni/Al ratio and are greatest for Ni/Al=1. It is also shown that these data correlate directly with the results obtained using the other experimental techniques.
Ion beam implantation of polymers has been shown to modify electrical and mechanical properties near the surface of the material. A complete understanding of the mechanism of modification and type of microstructure remaining as a result of this process has not yet been achieved. In this paper, we will discuss how recent advances in our understanding of these fundamental mechanisms and material processing techniques has led to a number ot prototypical applications. Specifically, the fundamentals of using ion implanted polymers as high value, small geometry resistors, temperature, strain, and vacuum sensing materials and as protective surfaces in chemically reactive environments.
Photolithographic processing capabilities of ion implanted polymer (IIP) films spin-coated onto silicon substrates were evaluated to determine the optimum conditions for producing stable, small geometry devices. Films which had a thickness approximately equivalent to or less than the mean range of ions in the polymer had good quality and stability, and could be patterned without change of conductivity to form small geometry resistors with dimensions of 10 to 50 micrometers. Sixteen-element, packaged resistor arrays were produced from ion implanted poly(styrene-acrylonitrile) films. High quality films with resistivities from 400 ohms/square to 10 megohms/square could be produced by the ion implantation technique. Suspended conducting polymer bridges were formed from IIP resistors by etching of a sacrificial layer underlying the IIP film. Electrical and mechanical properties of the bridges are presented.
For preparation of ZnO/CdS/Cu(In,Ga)Se2 solar cells, physical vapor deposition (PVD) was employed to deposit CdS buffer layers in ultrahigh vacuum on Se-decapped absorber surfaces, thus realizing an all ‘dry' fabrication process of the device. An 14.1% total area and 14.5% active area efficient ZnO/CdS/Cu(In,Ga)Se2 solar cell under AM1.5 conditions was achieved after annealing the as-prepared solar cells in air. Kelvin probe force microscopy (KPFM) measurements were carried out in-situ to monitor the initial growth of the CdS buffer layer on the absorber, as well as its electronic properties, in particular, the work function. It was observed that the PVD-CdS growth is initially inhibited at the absorber grain boundaries. Quantum efficiency measurements allowed us to suppose that during the initial growth stage a passivation of the grain boundaries occurs. The latter explains the higher short-circuit currents of the cells with PVD-CdS compared to their references with CdS grown by chemical bath deposition (CBD). The beneficial effect of the annealing seems to originate from a formation of a region with higher band gap than that of the absorber bulk and inverted conductivity type at the absorber surface, close to the CdS/Cu(In,Ga)Se2 interface, leading to a dramatic change in the electronic transport properties and finally, to a significant enhancement of the open-circuit voltage. Annealing of the ZnO/PVD-CdS/Cu(In,Ga)Se2 solar cells provides formation of PVDCdS/ Cu(In,Ga)Se2 interface with properties similar to that of reference samples with CBD-CdS.
Chalcopyrite-type thin films - CuInS2, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2 - in various completed solar cells were studied in cross-section by means of electron-backscatter diffraction (EBSD). Valuable information on grain sizes, local grain orientations, film textures, and grain boundaries were extracted from the EBSD linescans and maps. The grain-size distributions from the chalcopyrite-type thin films can be represented well by lognormal distribution functions. The EBSD measurements on CuGaSe2 thin film reveal a <110> fiber texture, in good agreement with x-ray diffraction texture analysis performed on the same sample. The EBSD maps from all samples studied exhibit considerable twinning in the chalcopyrite-type thin films. Indeed, the most frequent types of grain boundaries in these thin films are (near) Σ3 60°-<221> and 71°-<110> twins. It is shown that rotational 180°-<221> twins (which are symmetrically equivalent to 71°-<110>) are more frequently found than anion- or cation-terminated 60°-<221> twin boundaries.
For laboratory scale devices the transfer of the Cu(In,Ga)Se2 (CIGSe) thin film technology from a rigid float glass substrate to flexible titanium foil is achieved. Here we will highlight the effect of the rough, flexible substrate on the electrical and optical characteristics of the transparent window layers of such devices. The roughness of the substrate may give rise to changes in sheet resistance of the transparent front contact and in the reflectivity of the completed device. However, the devices deposited onto the kind of titanium foil substrate used in this work are smooth enough not to affect the sheet resistance; nevertheless optical effects are enough to affect the process window for an antireflective coating. With the use of an antireflective coating, a maximum efficiency of 17.4% could be reached for 0.5 cm2 area devices on glass.
Monolithic integration of sensing devices usually requires sharing the CMOS chip floor space between sensors and their readout electronics. Vertical integration of the sensor on top of the electronics allows one to have the full chip area dedicated to sensing. For light detection, the deposition of hydrogenated amorphous silicon (a-Si:H) photodiodes on top of CMOS readout circuits offers several advantages compared to standard CMOS imagers. The issues regarding the design of a-Si:H photodiodes, their integration and the influence of the CMOS chip design (i.e. its surface morphology) on a-Si:H diode performance are discussed. Examples of TFA sensors for vision and particle detection are also presented.
Image and particle sensors based on thin film on CMOS (TFC) technology, where a-Si:H detectors are vertically integrated on top of a CMOS chip, basically provide high sensitivity and low dark current densities (Jdark). However, as shown in previous work and as confirmed by the actual measurements, Jdark values depend on the topology of the chip and on the detector structure used.
The present paper describes a systematic study carried out, both with test structures on glass and also with a dedicated CMOS test chip designed by CERN. The increase in Jdark is shown to be related to border effects, and especially on the detailed structure of the pixel periphery. In all cases, lower Jdark are obtained when one uses metal-i-p instead of n-i-p configuration detectors. Transferring these results to the standard TFC sensors used by them, the authors have obtained values of Jdark as low as 20 pA/cm2 at -1 V reverse bias.
Indium sulfide buffer layers deposited by the Spray-Ion Layer Gas Reaction (Spray-ILGAR) technique have recently been used with Cu(In,Ga)(S,Se)2 absorbers giving cells with an efficiency equal to the cadmium sulfide references. In this paper we show the first results from cells prepared with Cu(In,Ga)Se2 absorbers (sulfur free). These cells reach an efficiency of 13.1% which remains slightly below the efficiency of the cadmium sulfide reference. However, temperature dependant current-voltage measurements reveal that the activation energy of the dominant recombination mechanism remains unchanged from the cadmium sulfide buffered cells indicating that recombination remains within the space charge region.