Glacial thermohaline circulation states of the northern Atlantic: The compatibility of modelling and observations

We present 3He data froma repeat section across Drake Passage, fromthree sections off the South American continent in the Pacific, at 28?S, 35?S, and 43?S, and fromthree sections in the Atlantic, eastward of the Malvinas, close to 35?W, and near the Greenwich Meridian. In Drake Passage, a distinct high-3He signal is observed that is centered just above the boundary of the Lower and the Upper Circumpolar Deep Water (LCDW, UCDW), and is concentrated towards the northern continental slope. 3He concentrations in the Antarctic Circumpolar Current (ACC) upstream of Drake Passage (World Ocean Circulation Experiment section P19 at 88?W) are markedly lower than those found in Drake Passage, and a regional source of primordial helium in the path of the ACC that might cause the high-3He feature can be ruled out. We explain the feature by addition of high-3He waters present at the 43?S Pacific section. This supports a previous, similar interpretation of a low-salinity anomaly in Drake Passage (Naveira Garabato et al., Deep- Sea Research I 49 (2002) 681), that is strongly related to the high-3He feature. Employing multiparameter water mass analysis (including 3He as a parameter), we find that deep waters as met at the 43?S Pacific section, flowing south along the South American continental slope, contribute substantially to the ACC waters in Drake Passage (fractions exceed 50% locally). Lesser, but laterally more extended contributions are found east of the Malvinas, and still smaller ones are present at 35?W and at the Greenwich Meridian. Using velocity measurements from one of the two Drake Passage sections, we estimate the volume transport of these waters to be 7.071.2 Sv, but the average transport may be somewhat lower as the other realization had a less pronounced signal. The enhanced 3He signature in Drake Passage is essentially confined north of the Polar Front. Further downstreamthe signature crosses this front, to the extent that at 35?W the contributions south and north of it are of similar magnitude. At the same time, the 3He levels north of the front are reduced due to a substantial admixture of low-3He North Atlantic Deep Water, such that 3He becomes highest south of the front. The flow of Southeast Pacific deep slope waters entering the ACC constitutes the predominant exit pathway of the primordial helium released in the deep Pacific, and represents a considerable fraction of the deep water return flow fromthe Pacific into the ACC. Therefore and also because the density range of the added deep slope waters is intermediate between those of UCDW and LCDW, they must be considered a distinct water mass. r 2003 Elsevier Ltd. All rights reserved

Individual variation evades the Prisoner's Dilemma

BACKGROUND: The Prisoner's Dilemma (PD) is a widely used paradigm to study cooperation in evolutionary biology, as well as in fields as diverse as moral philosophy, sociology, economics and politics. Players are typically assumed to have fixed payoffs for adopting certain strategies, which depend only on the strategy played by the opponent. However, fixed payoffs are not realistic in nature. Utility functions and the associated payoffs from pursuing certain strategies vary among members of a population with numerous factors. In biology such factors include size, age, social status and expected life span; in economics they include socio-economic status, personal preference and past experience; and in politics they include ideology, political interests and public support. Thus, no outcome is identical for any two different players. RESULTS: We show that relaxing the assumption of fixed payoffs leads to frequent violations of the payoff structure required for a Prisoner's Dilemma. With variance twice the payoff interval in a linear PD matrix, for example, only 16% of matrices are valid. CONCLUSIONS: A single player lacking a valid PD matrix destroys the conditions for a Prisoner's Dilemma, so between any two players, PD games themselves are fewer still (3% in this case). This may explain why the Prisoner's Dilemma has hardly been found in nature, despite the fact that it has served as a ubiquitous (and still instructive) model in studies of the evolution of cooperation

Preventing Repeat Victimization: A Systematic Review

This report presents a systematic review, including a statistical meta-analysis, of the effects of initiatives to prevent repeat victimization

Urban Heat Island and Vulnerable Population. The Case of Madrid

The Urban Heat Island effect shows the differences among temperatures in urban areas and the surrounding rural ones. Previous studies have demonstrated that temperature differences could be up to 8 °C during the hottest periods of summer in Madrid , and that it varies according to the urban structure. Associated to this effect, the impact of temperature increase over dwelling indoor thermal comfort seems to double cooling energy demand . In Madrid, fuel poor households already suffering from inadequate indoor temperatures can face important overheating problems and, as a consequence, relevant health problems could become more frequent and stronger. This poses an increment in mortality rates in risk groups that should be evaluated. This research is aimed at establishing the geospatial connection between the urban heat island and the most vulnerable population living in the city of Madrid. Hence, those areas most in need for an urban intervention can be detected and prioritized

OneGAN: Simultaneous Unsupervised Learning of Conditional Image Generation, Foreground Segmentation, and Fine-Grained Clustering

We present a method for simultaneously learning, in an unsupervised manner, (i) a conditional image generator, (ii) foreground extraction and segmentation, (iii) clustering into a two-level class hierarchy, and (iv) object removal and background completion, all done without any use of annotation. The method combines a Generative Adversarial Network and a Variational Auto-Encoder, with multiple encoders, generators and discriminators, and benefits from solving all tasks at once. The input to the training scheme is a varied collection of unlabeled images from the same domain, as well as a set of background images without a foreground object. In addition, the image generator can mix the background from one image, with a foreground that is conditioned either on that of a second image or on the index of a desired cluster. The method obtains state of the art results in comparison to the literature methods, when compared to the current state of the art in each of the tasks.Comment: To be published in the European Conference on Computer Vision (ECCV) 202

Directional emission of light from a nano-optical Yagi-Uda antenna

The plasmon resonance of metal nanoparticles can enhance and direct light from optical emitters in much the same way that radio frequency (RF) antennas enhance and direct the emission from electrical circuits. In the RF regime, a typical antenna design for high directivity is the Yagi-Uda antenna, which basically consists of a one-dimensional array of antenna elements driven by a single feed element. Here, we present the experimental demonstration of directional light emission from a nano-optical Yagi-Uda antenna composed of an array of appropriately tuned gold nanorods. Our results indicate that nano-optical antenna arrays are a simple but efficient tool for the spatial control of light emission.Comment: 4 pages, including 4 figure

Recurrent herpes zoster in the Shingles Prevention Study: Are second episodes caused by the same varicella-zoster virus strain?

Herpes zoster (HZ) is caused by reactivation of varicella zoster virus (VZV) that established latency in sensory and autonomic neurons during primary infection. In the Shingles Prevention Study (SPS), a large efficacy trial of live attenuated Oka/Merck zoster vaccine (ZVL), PCR-confirmed second episodes of HZ occurred in two of 660 placebo and one of 321 ZVL recipients with documented HZ during a mean follow-up of 3.13 years. An additional two ZVL recipients experienced a second episode of HZ in the Long-Term Persistence Substudy. All episodes of HZ were caused by wild-type VZV. The first and second episodes of HZ occurred in different dermatomes in each of these five participants, with contralateral recurrences in two. Time between first and second episodes ranged from 12 to 28 months. One of the five participants, who was immunocompetent on study enrollment, was immunocompromised at the onset of his first and second episodes of HZ. VZV DNA isolated from rash lesions from the first and second episodes of HZ was used to sequence the full-length VZV genomes. For the unique-sequence regions of the VZV genome, we employed target enrichment of VZV DNA, followed by deep sequencing. For the reiteration regions, we used PCR amplification and Sanger sequencing. Our analysis and comparison of the VZV genomes from the first and second episodes of HZ in each of the five participants indicate that both episodes were caused by the same VZV strain. This is consistent with the extraordinary stability of VZV during the replication phase of varicella and the subsequent establishment of latency in sensory ganglia throughout the body. Our observations also indicate that VZV is stable during the persistence of latency and the subsequent reactivation and replication that results in HZ