Inferring Causal Direction from Observational Data: A Complexity Approach

At the heart of causal structure learning from observational data lies a deceivingly simple question: given two statistically dependent random variables, which one has a causal effect on the other? This is impossible to answer using statistical dependence testing alone and requires that we make additional assumptions. We propose several fast and simple criteria for distinguishing cause and effect in pairs of discrete or continuous random variables. The intuition behind them is that predicting the effect variable using the cause variable should be ‘simpler’ than the reverse – different notions of ‘simplicity’ giving rise to different criteria. We demonstrate the accuracy of the criteria on synthetic data generated under a broad family of causal mechanisms and types of noise

Supersize the label: The effect of prominent calorie labeling on sales

Objectives Calorie labeling has been suggested as an antiobesity measure; however, evidence on its effects is scarce and formatting guidance not well defined. The aim of this study was to test the effects of prominent calorie labeling on sales of the labeled items. Methods Prominent calorie labels were posted in front of two popular items for a period of 1 mo. Sales were recorded for 2 mo consecutively, before and during labeling. Results Muffins sales (the higher-calorie item) fell by 30%, whereas sales of scones rose by 4%, a significant difference (χ2 = 10.258; P = 0.0014). Conclusions Calorie labeling is effective when noticed. Wider adoption of calorie labeling for all food businesses and strengthening legislation with formatting guidelines should be the next step in public health policy

Discretionary fiscal policy in the EMU context : an empirical approach (1981-2010) and the recent reform of European governance

This paper attempts to investigate how the Maastricht criteria and the Stability and Growth Pact (SGP) have impaired the capacity of Euro Zone (EZ) national authorities to conduct discretionary fiscal policy. We estimate fiscal determinants for the structural (discretionary) public deficit over the period of 1981-2010, estimating panel data equations in order to increase the strength of the test by enhancing the time series dimension of the data by the cross section. We find that the degree of the countrecyclicality of discretionary fiscal policy has been reduced significantly after the Maastricht Treaty. Also, there is empirical evidence that national fiscal rules have a significant positive impact in budgetary outcomes. Regarding the recent reform of the European governance framework, we consider that the context of the reform seems incapable of dealing with the factors which are responsible for the sovereign debt crisis. We stress the need for reforms in the financial sector which seem necessary to ensure in association with sound fiscal policies the stability in euro area.peer-reviewe

THE UTILITY OF OIL SHOWS IN THE HYDROCARBON EXPLORATION OF WESTERN GREECE

Στη Δυτική Ελλάδα εντοπίζονται πολλές ενδείξεις πετρελαίου, στην Ιόνια ζώνη κατά κύριο λόγο, αλλά και στην Προαπούλια και στη ζώνη Γαβρόβου. Αξιόλογες ενδείξεις υδρογονανθράκων έχουν επίσης εντοπιστεί στις περισσότερες από τις γεωτρήσεις πετρελαίου. Η συστηματική μελέτη των ενδείξεων αυτών βοηθάει αποτελεσματικά στην έρευνα πετρελαίου. Η παρουσία τους αποδεικνύει κατ' αρχή ότι στην περιοχή έχει ήδη λάβει χώρα πετρελαιογένεση και μετανάστευση, ενώ από τη μελέτη τους εξάγονται συμπεράσματα για το πετρελαϊκό σύστημα της περιοχής. Η ανάλυση των ενδείξεων έγινε με χημικές μεθόδους. Επειδή τα περισσότερα πετρέλαια στην επιφάνεια είναι βιοαποικοδομημένα, η μελέτη τους βασίζεται κυρίως σε μετρήσεις ισοτόπων του άνθρακα και σε χαρακτηριστικά βιοϊχνη που δεν επηρεάζονται από αλλοιώσεις. Η μελέτη έδειξε ότι τα πετρέλαια της Α. Ελλάδας μπορεί να καταταχθούν σε διαφορετικές ομάδες με βάση τα διαφορετικά τους χαρακτηριστικά. Εντοπίστηκαν πέντε ομάδες πετρελαίων, ενώ δύο από αυτές χωρίζονται σε δύο υποομάδες. Η διαφοροποίηση αποδεικνύει την παρουσία διαφορετικών οριζόντων μητρικών πετρωμάτων, που έδωσαν γένεση στα πετρέλαια αυτάA great number of oil shows are known in Western Greece, mainly in the Ionian zone, but also in the Preapulian and Gavrovo zones. Most of the wells drilled in the area have also identified oil shows. The systematic study of these oil shows provides a useful tool for the hydrocarbon exploration of this area. First of all the presence of oil shows indicates that oil generation and migration have certainly taken place. Furthermore by their study the petroleum systems of western Greece can be confirmed. Oil shows were analyzed using chemical methods. Because most surface oil shows are biodegraded, the study was mainly based on carbon isotopes measurements and on characteristic biomarker ratios. The oil shows can be classified into five main groups, based on their different compositions, while two of them are separated in two subgroups. This differentiation proves the presence of different source rock horizons, which have generated these oils

On the development of implicit and control processes in relation to substance use in adolescence

Adolescence is a period in which brain structures involved in motivation and cognitive control continue to develop and also a period in which many youth begin substance use. Dual-process models propose that, among substance users, implicit or automatically activated neurocognitive processes gain in relative influence on substance use behavior, while the influence of cognitive control or reflective processes weakens. There is evidence that a variety of implicit cognitive processes, such as attentional bias, biased action tendencies (approach bias), memory bias and at a neural level, cue reactivity, are associated with adolescent substance use. The impact of these implicit processes on the further development of addictive behaviors appears to depend on moderating factors, such as (premorbid) executive control functions. Clear negative effects of adolescent substance use on executive control functions generally have not been found using behavioral tasks, although some studies have identified subtle and specific effects on cognitive functioning

Financial sector and business cycles determinants in the EMU : an empirical approach (1996-2011)

This paper investigates potential business cycles determinants for the EMU countries among financial sector indicators examining at the same time the link between financial sector variables and business cycles volatility. We find that the total value of stocks traded, the private sector debt and the net inflows of FDI constitute significant determinants of business cycles fluctuations. Financial openness has an increasing effect on business cycles volatility while there is an unsettled relationship between financial depth and volatility. Another important finding of the paper is that the analysis provides evidence in favor of the occurrence of opportunistic political business cycles among EMU counterparts. The robustness of the above findings is verified via the use of relevant econometric methods such as EGLS, GLM and fixed-effect models.peer-reviewe

Foundation Optimization and Design for Replacement of the Woodrow Wilson Bridge

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. This paper will present results from a Pile Demonstration Program (PDP) that was conducted as part of the bridge replacement project, discuss the various aspects of the seismic design and analysis, and describe how those data were applied to optimize foundation design. The PDP included dynamic monitoring, static load tests and Statnamic load tests at several locations, to evaluate: (i) the pile driveability and associated parameters necessary for dynamic analysis; and (ii) the ultimate skin friction and end bearing values for design. The PDP provided a basis for eliminating static load tests during construction and construction quality control, and for evaluating potential settlement of the existing bridge. Although the seismicity of the region is low, considering the importance of this bridge and the consequences of potential damage during an earthquake, seismic issues were addressed thoroughly in the design of the new structure, including: (i) development of design spectra based on site-specific seismic hazard and ground motion analyses; (ii) implications of the complex soil profile and potential scour on the dynamic response of the foundations; (iii) Soil-Structure Interaction (SSI) analyses for the various foundation alternatives; and (iv) evaluation of the significance of the kinematic SSI effect on the piles. The presented case study proves how results of a pile demonstration program and extensive seismic studies can enable significant optimization of the foundation design and cost savings, and provide significant quality control during construction

Escape and fractionation of volatiles and noble gases from Mars-sized planetary embryos and growing protoplanets

Planetary embryos form protoplanets via mutual collisions, which can lead to the development of magma oceans. During their solidification, large amounts of the mantles' volatile contents may be outgassed. The resulting H$_2$O/CO$_2$ dominated steam atmospheres may be lost efficiently via hydrodynamic escape due to the low gravity and the high stellar EUV luminosities. Protoplanets forming later from such degassed building blocks could therefore be drier than previously expected. We model the outgassing and subsequent hydrodynamic escape of steam atmospheres from such embryos. The efficient outflow of H drags along heavier species (O, CO$_2$, noble gases). The full range of possible EUV evolution tracks of a solar-mass star is taken into account to investigate the escape from Mars-sized embryos at different orbital distances. The envelopes are typically lost within a few to a few tens of Myr. Furthermore, we study the influence on protoplanetary evolution, exemplified by Venus. We investigate different early evolution scenarios and constrain realistic cases by comparing modeled noble gas isotope ratios with observations. Starting from solar values, consistent isotope ratios (Ne, Ar) can be found for different solar EUV histories, as well as assumptions about the initial atmosphere (either pure steam or a mixture with accreted H). Our results generally favor an early accretion scenario with a small amount of accreted H and a low-activity Sun, because in other cases too much CO$_2$ is lost during evolution, which is inconsistent with Venus' present atmosphere. Important issues are likely the time at which the initial steam atmosphere is outgassed and/or the amount of CO$_2$ which may still be delivered at later evolutionary stages. A late accretion scenario can only reproduce present isotope ratios for a highly active young Sun, but then very massive steam atmospheres would be required.Comment: 61 pages, 7 figures, 3 tables, accepted to Icaru

Low Water–Demand Plants for Landscaping and Agricultural Cultivations – A Review Regarding Local Species of Epirus/Greece and Apulia/Italy

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