Can a pseudo-symmetry solve the cosmological constant problem?

A general no-go theorem dampens hope that the cosmological constant problem can be solved by a local symmetry mechanism. The possibility is considered here that this no-go theorem can be avoided by a pseudo-symmetry. A simple macroscopic effective field theory is constructed which admits an enhanced pseudo-symmetry in the absence of a cosmological term. It is pointed out that this pseudo-symmetry is an exact classical invariance of superstrings. The conjecture that this pseudo-symmetry survives in the quantum theory has several interesting consequences.Comment: Changes in language (including new title), and assorted perestroika. One new consequence of conjecture. 10 pages, uuencoded Postscript file. To appear in Phys.Lett.

Reduced-order neural network synthesis with robustness guarantees

In the wake of the explosive growth in smartphones and cyber-physical systems, there has been an accelerating shift in how data are generated away from centralized data toward on-device-generated data. In response, machine learning algorithms are being adapted to run locally on board, potentially hardware-limited, devices to improve user privacy, reduce latency, and be more energy efficient. However, our understanding of how these device-orientated algorithms behave and should be trained is still fairly limited. To address this issue, a method to automatically synthesize reduced-order neural networks (having fewer neurons) approximating the input-output mapping of a larger one is introduced. The reduced-order neural network's weights and biases are generated from a convex semidefinite program that minimizes the worst case approximation error with respect to the larger network. Worst case bounds for this approximation error are obtained and the approach can be applied to a wide variety of neural networks architectures. What differentiates the proposed approach to existing methods for generating small neural networks, e.g., pruning, is the inclusion of the worst case approximation error directly within the training cost function, which should add robustness to out-of-sample data points. Numerical examples highlight the potential of the proposed approach. The overriding goal of this article is to generalize recent results in the robustness analysis of neural networks to a robust synthesis problem for their weights and biases

Historical roots of Agile methods: where did “Agile thinking” come from?

The appearance of Agile methods has been the most noticeable change to software process thinking in the last fifteen years [16], but in fact many of the “Agile ideas” have been around since 70’s or even before. Many studies and reviews have been conducted about Agile methods which ascribe their emergence as a reaction against traditional methods. In this paper, we argue that although Agile methods are new as a whole, they have strong roots in the history of software engineering. In addition to the iterative and incremental approaches that have been in use since 1957 [21], people who criticised the traditional methods suggested alternative approaches which were actually Agile ideas such as the response to change, customer involvement, and working software over documentation. The authors of this paper believe that education about the history of Agile thinking will help to develop better understanding as well as promoting the use of Agile methods. We therefore present and discuss the reasons behind the development and introduction of Agile methods, as a reaction to traditional methods, as a result of people's experience, and in particular focusing on reusing ideas from histor

Organic Pollutants, Heavy Metals and Toxicity in Oil Spill impacted Salt Marsh Sediment Cores, Staten Island, New York City, USA

Sediment cores from Staten Island's salt marsh contain multiple historical oil spill events that impact ecological health. Microtox solid phase bioassay indicated moderate to high toxicity. Multiple spikes of TPH (6524 to 9586 mg/kg) and Σ16 PAH (15.5 to 18.9 mg/kg) were co-incident with known oil spills. A high TPH background of 400–700 mg/kg was attributed to diffuse sources. Depth-profiled metals Cu (1243 mg/kg), Zn (1814 mg/kg), Pb (1140 mg/kg), Ni (109 mg/kg), Hg (7 mg/kg), Cd 15 (mg/kg) exceeded sediment quality guidelines confirming adverse biological effects. Changes in Pb206/207 suggested three metal contaminant sources and diatom assemblages responded to two contamination events. Organic and metal contamination in Saw Mill Creek Marsh may harm sensitive biota, we recommend caution in the management of the 20–50 cm sediment interval because disturbance could lead to remobilisation of pre-existing legacy contamination into the waterway

Trading Methods and Family Strategies of Genoese People. Almería, XVIII century

Artículo de la sección: EstudiosEnfatizar la importancia de la documentación notarial para el estudio de un grupo social parece una valoración innecesaria. Este estudio pretende, a partir fundamentalmente de los protocolos notariales como núcleo de la investigación y del Catastro de Ensenada, complementados con otras fuentes, libros de Contadurías e Hipotecas de la sección de hacienda del Archivo Histórico Provincial de Almería, documentos de hidalguía y matrícula de extranjeros del Archivo Municipal de Almería, acercarse al flujo de mercaderes genoveses que, durante el siglo XVIII, se avecinda en la ciudad de Almería. La investigación se centra en los mecanismos que cuatro familias genovesas, domiciliadas en la ciudad de Almería durante el Setecientos: Schiafino-Aste, Schiafino- Schiafino, Schiafino-Ansaldo e Iluminatti-Marín, desarrollaron para conseguir la intervención en la administración local y la creación de unas prácticas mercantiles que, desde la ciudad de Almería y su jurisdicción, se extenderían hacia las villas del interior de la provincia y hacia una importante ramificación a lo largo de las costas del levante peninsular y de Andalucía occidental. No olvidaremos las relaciones que el grupo ligur almeriense mantuvo durante el siglo con su Génova natal, que cristalizaron en la creación de una compañía mercantil desarrollada en base a los intereses económicos de familias genovesas de Santa María de Camogli y de la ciudad de Almería. El análisis es un acercamiento, más que hacia aspectos económicos y al mundo del comercio, a la relación que se establece entre la formación de las familias y la creación de estrategias mercantiles que les llevará a la intervención en los mercados.To emphasize the notarial documentation for the study of a social group it seems to be an unnecessary valuation. This research expects basically, from the notarial protocols as the essence of the research work and from the Catastro of Ensenada, completed with other sources, Accountancy books and Mortgages of the section of finance from the Almerías 's Provincial Historical Record Office, nobility documents, and registration of foreigners from the Almería"s Town Record Office, to approach to the flow of Genoese merchants who, during the 18th century, comes near the town of Almería. The investigation is centred in the processes that four Genoese families established in the town of Almería during the Seven hundred, Schiafino-Aste, Shiafino-Shiafino,Shiafino-Ansaldo and Iluminatti-Marin, developped to get the participation in the local administration and the establishment of some trading methods which, from the city of Almería and its jurisdiction, would be spread over the inner small towns of the province and towards an important branch along the levant peninsular coasts and the west of Andalucía. We must not forget the relationship that the almeriense ligur group kept up during the century with its home town Genoa, crystallizing in the establishment of a trading company developped on tha basis of economical interests of Genoese families from Santa Maria of Camogli and the city of Almería. The analysis is a approach, more than to economical aspects and the business world, to the relationship that it is set up between the formation of the families and the establishment of trading strategies that will take them to the participation in the markets.Departamento de Historia Moderna y de América, Universidad de Granad

Inhomogeneous cosmologies with Q-matter and varying Λ\Lambda

Starting from the inhomogeneous shear--free Nariai metric we show, by solving the Einstein--Klein--Gordon field equations, how a self--interacting scalar field plus a material fluid, a variable cosmological term and a heat flux can drive the universe to its currently observed state of homogeneous accelerated expansion. A quintessence scenario where power-law inflation takes place for a string-motivated potential in the late--time dominated field regime is proposed.Comment: 11 pages, Revtex. To be published in Physical Review

The celebrity entrepreneur on television: profile, politics and power

This article examines the rise of the ‘celebrity entrepreneur’ on television through the emergence of the ‘business entertainment format’ and considers the ways in which regular television exposure can be converted into political influence. Within television studies there has been a preoccupation in recent years with how lifestyle and reality formats work to transform ‘ordinary’ people into celebrities. As a result, the contribution of vocationally skilled business professionals to factual entertainment programming has gone almost unnoticed. This article draws on interviews with key media industry professionals and begins by looking at the construction of entrepreneurs as different types of television personalities and how discourses of work, skill and knowledge function in business shows. It then outlines how entrepreneurs can utilize their newly acquired televisual skills to cultivate a wider media profile and secure various forms of political access and influence. Integral to this is the centrality of public relations and media management agencies in shaping media discourses and developing the individual as a ‘brand identity’ that can be used to endorse a range of products or ideas. This has led to policy makers and politicians attempting to mobilize the media profile of celebrity entrepreneurs to reach out and connect with the public on business and enterprise-related issues

Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil

Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii-like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare

A PXY-Mediated Transcriptional Network Integrates Signaling Mechanisms to Control Vascular Development in Arabidopsis

Vascular meristems generate the majority of biomass in higher plants. They constitute a bifacial stem cell population from which xylem and phloem are specified on opposing sides by positional signals. The PHLOEM INTERCALATED WITH XYLEM (PXY) receptor kinase promotes vascular cell division and organisation. However, how these functions are specified and integrated is unknown. Here, a putative PXY-mediated transcriptional regulatory network comprised of 690 transcription factor-promoter interactions was mapped. Among these interactions was a feed-forward loop containing transcription factors WUSCHEL HOMEOBOX RELATED 14 (WOX14) and TARGET OF MONOPTEROS 6 (TMO6), which each regulate the expression of a third transcription factor, LATERAL ORGAN BOUNDARIES DOMAIN 4 (LBD4). PXY signalling in turn regulates the WOX14, TMO6, LBD4 loop to control vascular proliferation. Genetic interaction between LBD4 and PXY suggests that LBD4 marks the phloem-procambium boundary, thus defining the shape of the vascular bundle. These data collectively support a novel mechanism that influences recruitment of cells into the phloem lineage, and defines the role of PXY signalling in this context to the arrangement of vascular tissue