Rough surface scattering in many-mode conducting channels: Gradient versus amplitude scattering

We study the effect of surface scattering on transport properties in many-mode conducting channels (electron waveguides). Assuming a strong roughness of the surface profiles, we show that there are two independent control parameters that determine statistical properties of the scattering. The first parameter is the ratio of the amplitude of the roughness to the transverse width of the waveguide. The second one, which is typically omitted, is determined by the mean value of the derivative of the profile. This parameter may be large, thus leading to specific properties of scattering. Our results may be used in experimental realizations of the surface scattering of electron waves, as well as for other applications (e.g., for optical and microwave waveguides)Comment: 6 pages, no figure

Is it ethical to avoid error analysis?

Machine learning algorithms tend to create more accurate models with the availability of large datasets. In some cases, highly accurate models can hide the presence of bias in the data. There are several studies published that tackle the development of discriminatory-aware machine learning algorithms. We center on the further evaluation of machine learning models by doing error analysis, to understand under what conditions the model is not working as expected. We focus on the ethical implications of avoiding error analysis, from a falsification of results and discrimination perspective. Finally, we show different ways to approach error analysis in non-interpretable machine learning algorithms such as deep learning.Comment: Presented as a poster at the 2017 Workshop on Fairness, Accountability, and Transparency in Machine Learning (FAT/ML 2017

Claim, offer and information in wage bargaining

A stylized private-information model on the determination of the initial works council claim and the initial firm (counter) offer is analyzed in the context of the Spanish Collective Bargaining system. The Spanish system forces agents to make initial offers at the beginning ot the negotiation process. Thus initial firm offers are expected to reveal very little information. Our findings confirm such a guess. Morever, we found that initial offers crucially depend on aggregate bargaining conditions, price expectations and those variables that reflect the characteristics of the negotiation unit. However, the latter set of variables enters differently in both offer equations

Two-person neuroscience and naturalistic social communication: The role of language and linguistic variables in brain-coupling research

Social cognitive neuroscience (SCN) seeks to understand the brain mechanisms through which we comprehend others? emotions and intentions in order to react accordingly. For decades, SCN has explored relevant domains by exposing individual participants to predesigned stimuli and asking them to judge their social (e.g., emotional) content. Subjects are thus reduced to detached observers of situations that they play no active role in. However, the core of our social experience is construed through real-time interactions requiring the active negotiation of information with other people. To gain more relevant insights into the workings of the social brain, the incipient field of two-person neuroscience (2PN) advocates the study of brain-to-brain coupling through multi-participant experiments. In this paper, we argue that the study of online language-based communication constitutes a cornerstone of 2PN. First, we review preliminary evidence illustrating how verbal interaction may shed light on the social brain. Second, we advance methodological recommendations to design experiments within language-based 2PN. Finally, we formulate outstanding questions for future research.Fil: García, Adolfo Martín. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Diego Portales; ChileFil: Ibanez Barassi, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Diego Portales; Chile. Universidad Autónoma del Caribe; Colombia. Australian Research Council Centre of Excellence in Cognition and its Disorders; Australi

Photodissociation chemistry footprints in the Starburst galaxy NGC 253

We report the first detection of PDR molecular tracers, namely HOC+, and CO+, and confirm the detection of the also PDR tracer HCO towards the starburst galaxy NGC 253, claimed to be mainly dominated by shock heating and in an earlier stage of evolution than M 82, the prototypical extragalactic PDR. Our CO+ detection suffers from significant blending to a group of transitions of 13CH3OH, tentatively detected for the first time in the extragalactic interstellar medium. These species are efficiently formed in the highly UV irradiated outer layers of molecular clouds, as observed in the late stage nuclear starburst in M 82. The molecular abundance ratios we derive for these molecules are very similar to those found in M 82. This strongly supports the idea that these molecules are tracing the PDR component associated with the starburst in the nuclear region of NGC 253. A comparison with the predictions of chemical models for PDRs shows that the observed molecular ratios are tracing the outer layers of UV illuminated clouds up to two magnitudes of visual extinction. Chemical models, which include grain formation and photodissociation of HNCO, support the scenario of a photo-dominated chemistry as an explanation to the abundances of the observed species. From this comparison we conclude that the molecular clouds in NGC 253 are more massive and with larger column densities than those in M 82, as expected from the evolutionary stage of the starbursts in both galaxies.Comment: 32 pages, 4 figures, Published in Ap

Not truly partnerless: Non-residential partnerships and retreat from marriage in Spain

In Spain, nearly two-thirds of women aged 20-34 have not yet entered their first union. However, almost half of them have a stable partner in a different household. Hence, the drop in marriage rates and low prevalence of cohabitation cannot be rightly interpreted as a decline in partnership formation, but rather as a postponement of co-residential unions. This paper examines the prevalence and determinants of non-residential stable partnerships among young adults (women aged 20-34), in relation to cohabitation and marriage, using a multinomial logit model of current partnership type. The analysis is based on data from the 1999 Spanish Fertility Survey.cohabitation, LAT, partnerships, Spain, union formation

Is Latin America starting to retreat from early and universal childbearing?

The 2000 censuses show that the proportion of women below age 30 who are mothers has dropped substantially in most Latin America countries, suggesting that the social imperative of early motherhood, which has long prevailed in the region, is weakening. Surveys conducted in 14 Latin American countries in 2006 also show a strong link between childlessness and higher education across several cohorts. We discuss whether the recent increase in childlessness among young women reflects a shift towards later childbearing, a novel trend in the Latin American context, and also whether it may signal an emerging retreat from universal childbearing in the region.childlessness, fertility, first birth, Latin America