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 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.
Generalized Algebraic Data Types, or simply GADTs, can encode non-trivial properties in the types of the constructors. Once such properties are encoded in a datatype, however, all code manipulating that datatype must provide proof that it maintains these properties in order to typecheck. In this paper, we take a step toward gradualizing these obligations. We introduce a tool, Ghostbuster, that produces simplified versions of GADTs which elide selected type parameters, thereby weakening the guarantees of the simplified datatype in exchange for reducing the obligations necessary to manipulate it. Like ornaments, these simplified datatypes preserve the recursive structure of the original, but unlike ornaments, we focus on information-preserving bidirectional transformations. Ghostbuster generates type-safe conversion functions between the original and simplified datatypes, which we prove are the identity function when composed. We evaluate a prototype tool for Haskell against thousands of GADTs found on the Hackage package database, generating simpler Haskell'98 datatypes and round-trip conversion functions between the two.
Breast milk is the only source of the essential amino acid tryptophan (TRP) in breast-fed infants. Low levels of TRP could have implications for infant neurodevelopment. The objectives of the present study were to compare the relationship of TRP and its neuroactive pathway metabolites kynurenine (Kyn) and kynurenic acid (KynA) in preterm and term expressed breast milk (EBM) in the first 14 d following birth, and the relationship of TRP metabolism to maternal stress and immune status. A total of twenty-four mothers were recruited from Cork University Maternity Hospital: twelve term (>38 weeks) and twelve preterm (<35 weeks). EBM samples were collected on days 7 and 14. Free TRP, Kyn and KynA were measured using HPLC, total TRP using MS, cytokines using the Meso Scale Discovery (MSD) assay system, and cortisol using a cortisol ELISA kit. Although total TRP was higher in preterm EBM in comparison with term EBM (P < 0·05), free TRP levels were lower (P < 0·05). Kyn, KynA and the Kyn:TRP ratio increased significantly in term EBM from day 7 to day 14 (P < 0·05), but not in preterm EBM. TNF-α, IL-6 and IL-8 were higher in day 7 preterm and term EBM in comparison with day 14. There were no significant differences between term and preterm EBM cortisol levels. Increased availability of total TRP, lower levels of free TRP and alterations in the temporal dynamics of TRP metabolism in preterm compared with term EBM, coupled with higher EBM inflammatory markers on day 7, may have implications for the neurological development of exclusively breast-fed preterm infants.
We used a terrestrial radar interferometer (TRI) at Helheim Glacier, Greenland, in August 2013, to study the effects of tidal forcing on the terminal zone of this tidewater glacier. During our study period, the glacier velocity was up to 25 m d–1. Our measurements show that the glacier moves out of phase with the semi-diurnal tides and the densely packed melange in the fjord. Here detrended glacier displacement lags behind the forecasted tidal height by ∼8 hours. The transition in phase lag between the glacier and the melange happens within a narrow (∼500 m) zone in the fjord in front of the ice cliff. The TRI data also suggest that the impact of tidal forcing decreases rapidly up-glacier of the terminus. A flowline model suggests this pattern of velocity perturbation is consistent with weak ice flowing over a weakly nonlinear bed.
Outlet glaciers undergo rapid spatial and temporal changes in flow velocity during calving events. Observing such changes requires both high temporal and high spatial resolution methods, something now possible with terrestrial radar interferometry. While a single such radar provides line-of-sight velocity, two radars define both components of the horizontal flow field. To assess the feasibility of obtaining the two-dimensional (2-D) flow field, we deployed two terrestrial radar interferometers at Jakobshavn Isbrae, a major outlet glacier on Greenland's west coast, in the summer of 2012. Here, we develop and demonstrate a method to combine the line-of-sight velocity data from two synchronized radars to produce a 2-D velocity field from a single (3 min) interferogram. Results are compared with the more traditional feature-tracking data obtained from the same radar, averaged over a longer period. We demonstrate the potential and limitations of this new dual-radar approach for obtaining high spatial and temporal resolution 2-D velocity fields at outlet glaciers.
The degree to which prehispanic societies in the northern upland Southwest were hierarchical or egalitarian is still debated and seems likely to have changed through time. This paper examines the plausibility of village-spanning polities in the northern Southwest by simulating the coevolution of hierarchy and warfare using extensions to the Village Ecodynamics Project's agent-based model. We additionally compile empirical data on the population size distribution of habitations and ritual spaces (kivas) and the social groups that used them in three large regions of the Pueblo Southwest and analyze these through time. All lines of evidence refute an “autonomous village” model during the Pueblo II period (A.D. 890–1145); rather, they support the existence of village-spanning polities during the Pueblo II and probably into the Pueblo III period (A.D. 1145–1285) in some areas. One or more polities connecting the northern Southwest, with tribute flowing to an apex in Chaco Canyon, appears plausible during Pueblo II for the areas we examine. During Pueblo III, more local organizations likely held sway until depopulation in the late thirteenth century.
Recent scholarship in political science identifies emotions as an important antecedent to political behavior. Existing work, however, has focused much more on the political effects of emotions than on their causes. Here, we begin to examine how personality moderates emotional responses to political events. We hypothesized that the personality trait need for affect (NFA) would moderate the emotions evoked by disturbing political news. Drawing data from a survey experiment conducted on a national sample, we find that individuals high in NFA have an especially vivid emotional response to disturbing news—a moderating relationship that has the potential to surpass those associated with symbolic attachments.
Childhood and adolescence coincide with rapid structural and functional maturation of brain networks implicated in Theory of Mind (ToM); however, the impact of paediatric traumatic brain injury (TBI) on the development of these higher order skills is not well understood. ToM can be partitioned into conative ToM, defined as the ability to understand how indirect speech acts involving irony and empathy are used to influence the mental or affective state of the listener; and affective ToM, concerned with understanding that facial expressions are often used for social purposes to convey emotions that we want people to think we feel. In a sample of 84 children with mild-severe TBI and 40 typically developing controls, this study examined the effect of paediatric TBI on affective and conative ToM; and evaluated the respective contributions of injury-related factors (injury severity/lesion location) and non-injury-related environmental variables (socio-economic status (SES)/family functioning) to long-term ToM outcomes. Results showed that the poorest ToM outcomes were documented in association with mild-complicated and moderate TBI, rather than severe TBI. Lesion location and SES did not significantly contribute to conative or affective ToM. Post-injury family affective responsiveness was the strongest and most significant predictor of conative ToM. Results suggest that clinicians should exercise caution when prognosticating based on early clinical indicators, and that group and individual-level outcome prediction should incorporate assessment of a range of injury- and non-injury-related factors. Moreover, the affective quality of post-injury family interactions represents a potentially modifiable risk factor, and might be a useful target for family-centred interventions designed to optimise social cognitive outcomes after paediatric TBI.
Trials evaluating efficacy of omega-3 highly unsaturated fatty acids (HUFAs) in major depressive disorder report discrepant findings.
To establish the reasons underlying inconsistent findings among randomised controlled trials (RCTs) of omega-3 HUFAs for depression and to assess implications for further trials.
A systematic bibliographic search of double-blind RCTs was conducted between January 1980 and July 2014 and an exploratory hypothesis-testing meta-analysis performed in 35 RCTs including 6665 participants receiving omega-3 HUFAs and 4373 participants receiving placebo.
Among participants with diagnosed depression, eicosapentaenoic acid (EPA)-predominant formulations (>50% EPA) demonstrated clinical benefits compared with placebo (Hedge's G = 0.61, P<0.001) whereas docosahexaenoic acid (DHA)-predominant formulations (>50% DHA) did not. EPA failed to prevent depressive symptoms among populations not diagnosed for depression.
Further RCTs should be conducted on study populations with diagnosed or clinically significant depression of adequate duration using EPA-predominant omega-3 HUFA formulations.
Neighboring tidewater glaciers often exhibit asynchronous dynamic behavior, despite relatively uniform regional atmospheric and oceanic forcings. This variability may be controlled by a combination of local factors, including glacier and fjord geometry, fjord heat content and circulation, and glacier surface melt. In order to characterize and understand contrasts in adjacent tidewater glacier and fjord dynamics, we made coincident ice-ocean-atmosphere observations at high temporal resolution (minutes to weeks) within a 10 000 km2 area near Uummannaq, Greenland. Water column velocity, temperature and salinity measurements reveal systematic differences in neighboring fjords that imply contrasting circulation patterns. The observed ocean velocity and hydrography, combined with numerical modeling, suggest that subglacial discharge plays a major role in setting fjord conditions. In addition, satellite remote sensing of seasonal ice flow speed and terminus position reveal both speedup and slow-down in response to melt, as well as differences in calving style among the neighboring glaciers. Glacier force budgets and modeling also point toward subglacial discharge as a key factor in glacier behavior. For the studied region, individual glacier and fjord geometry modulate subglacial discharge, which leads to contrasts in both fjord and glacier dynamics.
Los Alamos National Laboratory’s ALEXIS satellite (a wide area EUV monitoring instrument) was launched April 25, 1993. Due to the damage sustained at launch by the satellite, the ALEXIS project team has had to spend over a year devising new methods to determine spacecraft attitude knowledge, essential for putting photons back on the sky correctly. These efforts have been successful and currently the ALEXIS attitude solutions are precise to better than 0.5 degree close to the original 0.25 degree pre-flight specification. This paper will discuss the number and types of point sources that have been revealed in the ALEXIS data to date. We will also discuss ALEXIS observations of the June, 1994 super outburst of the Cataclysmic Variable VW Hyi, a program to look for simultaneous EUV emission from Gamma Ray Bursts, as well as an effort to detect EUV transients with a 12 – 24 hour response time.
The main objective of our target article was to sketch the empirical case for the importance of selection at the level of groups on cultural variation. Such variation is massive in humans, but modest or absent in other species. Group selection processes acting on this variation is a framework for developing explanations of the unusual level of cooperation between non-relatives found in our species. Our case for cultural group selection (CGS) followed Darwin's classic syllogism regarding natural selection: If variation exists at the level of groups, if this variation is heritable, and if it plays a role in the success or failure of competing groups, then selection will operate at the level of groups. We outlined the relevant domains where such evidence can be sought and characterized the main conclusions of work in those domains. Most commentators agree that CGS plays some role in human evolution, although some were considerably more skeptical. Some contributed additional empirical cases. Some raised issues of the scope of CGS explanations versus competing ones.
Past research shows that candidates' racial identities influence the assumptions that voters draw about how they will behave in office. In a national survey experiment examining televised candidate advertisements, we find evidence that stereotypes differ both in their potency and how vulnerable they are to disconfirmation. Consistent with previous work, black candidates are broadly assumed to be more liberal than white candidates, although the effect is notably small in magnitude. Yet when it comes to more specific stereotypes—how black candidates will behave on individual issues—effects are not only much larger, but also more contingent on what information is available. We find that by providing a small bit of ideological information, black candidates can overcome the assumption that they will enact liberal policies as concerns taxation and non-racialized aspects of social welfare policy. But it is much more difficult for them to overturn the assumption that they will prioritize aid to minorities while in office.
Congenital abnormalities of the coronary arteries in the absence of structural heart disease account for a small but interesting percentage of cardiac lesions in children. Their presentation may vary from incidental identification to aborted/sudden cardiac death. Patients with aborted sudden death episodes will require significant support if they develop extensive ischaemic myocardial injury. Ultimately, surgical repair should be carried out as soon as haemodynamic stability is attained and the neurological status is evaluated. The aims of this article were to provide a review of congenital abnormalities of the coronary arteries most commonly seen in children in the ICU as well as to review the current critical-care management thereof.
The possibility that citizens expose themselves to information in biased ways—so-called selective exposure—has acquired new importance as the media environment has evolved to provide more choices concerning what to watch and read. But evidence for the most prominent idea in selective exposure research—that citizens prefer attitude-consistent information—is notably mixed. Methodological challenges likely contribute to the inconclusive nature of findings, as researchers face trade-offs between the artificiality of lab environments and the difficult-to-disentangle confounds of observational analysis. We improve understanding of selective exposure in two ways. First, we consider how message aspects other than attitude-consistency affect exposure decisions. Second, we study selective exposure with an innovative field experiment conducted in the United States that addresses limitations of other approaches. Our results allow us to reach more confident conclusions about the prevalence of motivated selective exposure, and help to illuminate underpinnings of the oft-lamented tendency for campaign media to focus on candidate miscues rather than substantive policy differences.
As part of a general inquiry into mental mechanisms that operate outside conscious awareness, experimental psychology has recently established the presence and importance of “implicit attitudes.” The purpose of our paper is to compare the roles played by implicit and explicit prejudice in politics. Relying on two national surveys of the American electorate that included standard measures of implicit and explicit prejudice, we provide a systematic comparison of prejudice’s political effects: for the candidates Americans choose, the policies they favor, the assessments they make of government performance, and the racialized information they absorb. We find that implicit and explicit prejudice provide radically different pictures of racial politics in America.
We will identify new molecules in the interstellar medium by comparing a catalog of theoretical spectra generated by the NASA Ames quantum chemistry group with recent high-resolution astronomical line surveys.
Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains that bear on the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is “no,” then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is “yes” and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules (institutions) that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation.