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.
Derived equivalences of twisted K3 surfaces induce twisted Hodge isometries between them; that is, isomorphisms of their cohomologies which respect certain natural lattice structures and Hodge structures. We prove a criterion for when a given Hodge isometry arises in this way. In particular, we describe the image of the representation which associates to any autoequivalence of a twisted K3 surface its realization in cohomology: this image is a subgroup of index
in the group of all Hodge isometries of the twisted K3 surface. We show that both indices can occur.
Airplanes and airports are in potential danger during transport of highly toxic chemicals, and accidents can occur if the wrapping material is damaged. The chemicals are listed and classified by the International Civil Aviation Authority ICAO) (7). They are subdivided into nine classes, each marked by a special symbol. The classification is derived from the most important properties of the chemicals in relation to the air transport (Table 1). Special positions are listed in class 6. This does not mean, however, that the chemicals of all other classes are non-toxic. On the contrary, highly toxic substances also exist in each other class. For example, class 2 “compressed gas” includes dangerous toxic substances such as hydrochloric acid, fluorine, carbon monoxide or sulphur dioxide. Class 3 (“flammable liquids”) includes benzene, methanol, acrylonitrile and ethyl methyl ketone, for example. In class 6 (“poisons”), special poisons are listed such as tetraethyl lead, dimethyl mercury, organophosphates and aniline. Class 8 (“corrosives”) consists of poisons like bromide, dimethyl sulphate, phorphorous trichloride and hydrofloric acid.
Cubic boron nitride (cBN) is a synthetic wide band gap material that has attracted attention due to its high thermal conductivity, optical transparency and optical emission. In this work, defects in cBN have been investigated using experimental and theoretical X-ray absorption near edge structure (XANES). Vacancy and O substitutional defects were considered, with O substituted at the N site (ON) to be the most energetically favorable. All defects produce unique signatures in either the B or N K-edges and can thus be identified using XANES. The calculations coupled with electron-irradiation / annealing experiments strongly suggest that ON is the dominant defect in irradiated cBN and remains after annealing. This defect is a likely source of optical emission in cBN.
Background: It has been suggested that the behavioural activation (BA) treatments for depression unfold their effects, at least partly, through changes in approach and avoidance tendencies. However, as yet, little research has examined the cognitive effects of these interventions. Aims: This study investigated the impact of a single session of BA on depressive symptomatology, self-reported avoidance, and behavioural approach and avoidance tendencies. Method: Forty-six patients with a diagnosis of Major Depression were recruited from primary care psychological therapies services and block randomized to either a single session of behavioural activation (n = 22) or waiting list control (n = 24) delivered by an unblinded therapist. Self-reports of symptoms and cognitive factors were assessed before and after the one-week intervention phase. Approach and avoidance behavioural tendencies were assessed using the Approach-Avoidance Task (AAT). Results: Data from 40 participants (n = 20 in each group) was available for analyses. Depressive symptoms significantly decreased, and activation significantly increased from before to after treatment in the treatment group, but not in the control group. Performance on the AAT showed a trend indicating increased approach to positive valence stimuli in the treatment group, but not in the control group. Mediational analyses indicated small indirect effects of self-reported change in activation as mediators of the effect of condition on symptoms. Conclusions: The findings suggest that a single session of BA can have significant effects on symptoms in clinically depressed patients. Results hint at the possibility that increased behavioural approach might mediate the effect of BA.
Concentrating on the production of knowledge of poverty and homelessness, this article discusses how particular spatial settings influenced the construction of social problems in the 1960s and 1970s. Exploring the practices of three kinds of knowledge producers – social scientists in academic circles, ‘practitioners cum activists’ engaging in advocacy research and experts in governmental committees – the analysis focuses on the early stages of a rediscovery of poverty in Western Europe as it was debated in international fora as well as in West Germany and France. It shows that the way in which poverty was represented as a new challenge to Western ‘affluent societies’ was in many respects an urban story, as the ongoing housing crisis and newly defined problem areas served as major points of reference for the revived interest in social deprivation. Moreover, urban actors – locally active NGOs and municipal authorities – played a preeminent role in launching debates on the apparent paradox of poverty in affluence. With their own work often grounded in particular urban problem zones, many contemporary observers tended to spatialise poverty. For them, poverty was bound to particular places; it was an exceptional sphere that helped generate a particular behaviour that made it difficult for ‘the poor’ to rise. While a growing part of the population had access to housing of a standard previously reserved to the middle class and had become able to choose where to live, life in peripheral shantytowns or dilapidated inner cities became the ultimate signifier of a social position beyond the established class structure.
The sky is full of variable and transient sources on all time scales, from milliseconds to decades. Planck's regular scanning strategy makes it an ideal instrument to search for variable sky signals in the millimetre and submillimetre regime, on time scales from hours to several years. A precondition is that instrumental noise and systematic effects, caused in particular by non-symmetric beam shapes, are properly removed. We present a method to perform a full sky blind search for variable and transient objects at all Planck frequencies.
The scalable storage of renewable energy by means of converting water to hydrogen fuels electrochemically hinges on fundamental improvements in catalytic materials. However, many applications exist where an extended lifetime is virtually crucial for their functionality and success, e.g. in case of limited accessibility such as tire pressure sensors or biomedical implants. For these kinds of applications, the ultimate power supply should be a self-renewing energy source. This strategy is pursued by the concept of Micro Energy Harvesting (MEH). Within a MEH system a micro generator converts ambient energy to electrical energy for driving an application. Unfortunately, it is not ensured that the ambient energy level will maintain always high enough to provide sufficient power to the system as harvested energy usually manifests itself in rather irregular, random and low-energy bursts. One appealing form of integrated energy storage is the use of H2/air, a so called fuel cell type (FC) battery. Such devices promise very high volumetric energy densities of more than 2000 Wh/l. Consequently, this type of battery has recently attracted more and more attention and primary as well as secondary cells have been realized. Alkaline polymer electrolyte fuel cells have been recognized as the most promising solution in order to overcome the dependency on noble metal catalysts. Nevertheless, further improvements for these kinds of fuel cells have to be reached with respect to high power. Therefore, one promising approach is to increase the skin surface of porous chromium decorated nickel electrodes for enhancement of exchange current density by forming three-dimensional (3D) microstructures directly into the electrode. Therefore, a novel laser structuring process was applied using ultrashort laser pulses. Ultrashort laser processing of complex multimaterial systems for energy storage allow for precise material removal without changing the material properties. By applying this novel laser-based structuring technique, 3D microstructures could be formed permitting shortened diffusion lengths between the electrolyte and the electrode surface being necessary for increased exchange current densities.
Studies of trade routes across Southeast Asia in prehistory have hitherto focused largely on archaeological evidence from Mainland Southeast Asia, particularly the Thai Peninsula and Vietnam. The role of Indonesia and Island Southeast Asia in these networks has been poorly understood, owing to the paucity of evidence from this region. Recent research has begun to fill this void. New excavations at Sembiran and Pacung on the northern coast of Bali have produced new, direct AMS dates from burials, and analytical data from cultural materials including pottery, glass, bronze, gold andsemi-precious stone, as well as evidence of local bronze-casting. This suggests strong links with the Indian subcontinent and Mainland Southeast Asia from the late first millennium BC, some 200 years earlier than previously thought.
Negative cognitive bias and aberrant neural processing of emotional faces are trait-marks of depression. Yet it is unclear whether these changes constitute an endophenotype for depression and are also present in healthy individuals with hereditary risk for depression.
Thirty healthy, never-depressed monozygotic (MZ) twins with a co-twin history of depression (high risk group: n = 13) or without co-twin history of depression (low-risk group: n = 17) were enrolled in a functional magnetic resonance imaging (fMRI) study. During fMRI, participants viewed fearful and happy faces while performing a gender discrimination task. After the scan, they were given a faces dot-probe task, a facial expression recognition task and questionnaires assessing mood, personality traits and coping strategies.
High-risk twins showed increased neural response to happy and fearful faces in dorsal anterior cingulate cortex (ACC), dorsomedial prefrontal cortex (dmPFC), pre-supplementary motor area and occipito-parietal regions compared to low-risk twins. They also displayed stronger negative coupling between amygdala and pregenual ACC, dmPFC and temporo-parietal regions during emotional face processing. These task-related changes in neural responses in high-risk twins were accompanied by impaired gender discrimination performance during face processing. They also displayed increased attention vigilance for fearful faces and were slower at recognizing facial expressions relative to low-risk controls. These effects occurred in the absence of differences between groups in mood, subjective state or coping.
Different neural response and functional connectivity within fronto-limbic and occipito-parietal regions during emotional face processing and enhanced fear vigilance may be key endophenotypes for depression.
Amid concerns for a regulatory void in transnational fields, the principle of private regulation has become institutionalized. Many sectors have seen the emergence of multiple and overlapping standards. When comparing the sectors, there is considerable variation in standard multiplicity. We build on three institutional perspectives that have been put forward to explain the emergence of sustainability standards – the economic, idealist and political-institutional perspectives – to analyze the phenomenon of standard multiplicity. Each perspective reflects a different kind of action logic and is simultaneously present and accessible to various parties involved. Based on a cross-sector analysis of standards multiplicity in the forestry, coffee and textile sectors, this article seeks to make two contributions. First, whereas these three perspectives have been presented as competing, we propose that they are complementary in offering partial explanations for different episodes in the dynamics underlying standards multiplicity in different sectors. Second, whereas most studies have analyzed standard setting in single sectors and thus have understood it as being an intra-sector phenomenon, our cross-sector analysis of the dynamics of standard setting suggests that it is propelled by both sector-specific contingencies and experiences as well as by the experiences from other sectors.
This article presents a panel discussion on the integration of collaborative empiricism, specifically Socratic Questioning, into cognitive behaviour therapy. The panel comprised experts in research and practice who had been invited as keynote presenters for the 34th National Conference for the Australian Association of Cognitive and Behaviour Therapy, held in Sydney, Australia. Experts responded to questions regarding (a) the definition of Socratic dialogue, and (b) whether the purpose of Guided Discovery using Socratic Questioning is to impart information, correct, or dispute patient cognitions. The session was well attended by mental health professionals from around the globe and the panel enjoyed the opportunity to discuss questions and comments from those in attendance. This article presents this exchange so that the broader AACBT membership may benefit from the ideas and comments generated.
Short-term antidepressant administration has been reported to decrease amygdala response to threat in healthy volunteers and depressed patients. Neuroticism (N) is a risk factor for depression but has also been associated with slow or incomplete remission with antidepressant drug treatment. Our aim was to investigate early selective serotonin reuptake inhibitor (SSRI) administration neural effects on implicit processing of fearful facial expressions in volunteers with high levels of N.
Highly neurotic subjects received 20 mg/day citalopram versus placebo for 7 days in a double-blind, between-groups design. On the last day haemoperfusion and functional magnetic resonance imaging (fMRI) data during a gender discrimination task with fearful and happy faces were acquired. A control group of non-neurotic volunteers was also tested.
High-N volunteers had reduced responses to threatening facial expressions across key neural circuits compared to low-N volunteers. SSRI treatment was found to elevate resting perfusion in the right amygdala, increase bilateral amygdalae activation to positive and negative facial expressions and increase activation to fearful versus happy facial expressions in occipital, parietal, temporal and prefrontal cortical areas.
These results suggest that 7 days of SSRI administration can increase neural markers of fear reactivity in subjects at the high end of the N dimension and may be related to early increases in anxiety and agitation seen early in treatment. Such processes may be involved in the later therapeutic effects through decreased avoidance and increased learning about social ‘threat’ cues.
This study describes the application of a dc-plasma to stimulate growth of InP in a MOCVD system using In(C2 H5)3 and PH3. Precracking of PH3 enables a substantial reduction of the growth temperature to well below 500 K. In addition, at temperatures where InP is commonly deposited (∼870 K) a significant lowering of the V/III input ratio is possible. The fact that InP is relatively insensitive to low energy ion bombardement permits deposition in a canal ray configuration.
Shallow symmetric and asymmetric GaAs/InGaAs/(Al)GaAs single quantum wells with an indium content of 5% and less, grown by MBE, show striking differences in their photoluminescence spectra. Unlike the symmetric case, the asymmetric quantum wells are found to have no bound ground state below a certain thickness, which depends on the indium content of the quantum well and the aluminium content of the barrier. For a set of asymmetric samples investigated here, the bound state vanishes at about 60Å.
Photoluminescence excitation measurements on shallow symmetric and asymmetric wells show a series of narrow lines with oscillator strengths many times exceeding those of the band to band transition. These lines can be identified with excited excitonic transitions including heavy and light holes.
The thermoelectric transport properties of superlattices have been studied using an exact solution of the Boltzmann equation. The role of heat transport along the barrier layers, of carrier tunneling through the barriers, of valley degeneracy and of the well width and energy dependences of the carrier-phonon scattering rates on the thermoelectric figure of merit are given. Calculations are given for Bi2Te3 and for PbTe, and the results of recent experiments are discussed.