2,700 research outputs found
A remark on the BRST symmetry in the Gribov-Zwanziger theory
We show that the soft breaking of the BRST symmetry arising in the
Gribov-Zwanziger theory can be converted into a linear breaking upon
introduction of a set of BRST quartets of auxiliary fields. Due to its
compatibility with the Quantum Action Principle, the linearly broken BRST
symmetry can be directly converted into a suitable set of useful Slavnov-Taylor
identities. As a consequence, it turns out that the renormalization aspects of
the Gribov-Zwanziger theory can be addressed by means of the cohomology of a
nilpotent local operatorComment: 11 pages, final version to appear in Phys. Rev.
On the calibration of the relation between geometric albedo and polarimetric properties for the asteroids
We present a new extensive analysis of the old problem of finding a
satisfactory calibration of the relation between the geometric albedo and some
measurable polarization properties of the asteroids. To achieve our goals, we
use all polarimetric data at our disposal. For the purposes of calibration, we
use a limited sample of objects for which we can be confident to know the
albedo with good accuracy, according to previous investigations of other
authors. We find a new set of updated calibration coefficients for the
classical slope - albedo relation, but we generalize our analysis and we
consider also alternative possibilities, including the use of other
polarimetric parameters, one being proposed here for the first time, and the
possibility to exclude from best-fit analyzes the asteroids having low albedos.
We also consider a possible parabolic fit of the whole set of data.Comment: Accepted by MNRA
Simulated Greenland Surface Mass Balance in the GISS ModelE2 GCM: Role of the Ice Sheet Surface
The rate of growth or retreat of the Greenland and Antarctic ice sheets remains a highly uncertain component of future sea level change. Here we examine the simulation of Greenland ice sheet surface mass balance (GrIS SMB) in the NASA Goddard Institute for Space Studies (GISS) ModelE2 General Circulation Model (GCM). GCMs are often limited in their ability to represent SMB compared with polarregion Regional Climate Models (RCMs). We compare ModelE2 simulated GrIS SMB for presentday (19962005) simulations with fixed ocean conditions, at a spatial resolution of 2 latitude by 2.5 longitude (~200 km), with SMB simulated by the Modle Atmosphrique Rgionale (MAR) RCM (19962005 at a 25 km resolution). ModelE2 SMB agrees well with MAR SMB on the whole, but there are distinct spatial patterns of differences and large differences in some SMB components. The impact of changes to the ModelE2 surface are tested, including a subgridscale representation of SMB with surface elevation classes. This has a minimal effect on ice sheetwide SMB, but corrects local biases. Replacing fixed surface albedo with satellitederived values and an agedependent scheme has a larger impact, increasing simulated melt by 60100%. We also find that lower surface albedo can enhance the effects of elevation classes. Reducing ModelE2 surface roughness length to values closer to MAR reduces sublimation by ~50%. Further work is required to account for meltwater refreezing in ModelE2, and to understand how differences in atmospheric processes and model resolution influence simulated SMB
Renormalizability of the linearly broken formulation of the BRST symmetry in presence of the Gribov horizon in Landau gauge Euclidean Yang-Mills theories
In previous work arXiv:1009.4135 we have shown that the soft breaking of the
BRST symmetry arising within the Gribov-Zwanziger framework can be converted
into a linear breaking, while preserving the nilpotency of the BRST operator.
Due to its compatibility with the Quantum Action Principle, the linearly broken
BRST symmetry directly translates into a set of Slavnov-Taylor identities. We
show that these identities guarantee the multiplicative renormalizability of
both Gribov-Zwanziger and Refined Gribov-Zwanziger theories to all orders. The
known property that only two renormalization factors are needed is recovered.
The non-renormalization theorem of the gluon-ghost-antighost vertex as well as
the renormalization factor of the Gribov parameter are derived within the
linearly broken formulation.Comment: 20 pages, references added, version accepted for publication in
Physical Review
A simulation tool for analysis and design of reverse electrodialysis using concentrated brines
Reverse Electrodialysis (SGP-RE or RED) represents a viable technology for the conversion of the Salinity Gradient Power into electric power.
A comprehensive model is proposed for the RED process using sea or brackish water and concentrated brine as feed solutions. The goals were (i) reliably describing the physical phenomena involved in the process and (ii) providing information for optimal equipment design. For such purposes, the model has been developed at two different scales of description: a lower scale for the repeating unit of the system (cell pair), and a higher scale for the entire equipment (stack).
The model was implemented in a process simulator, validated against original experimental information and then used to investigate the influence of the main operating factors and on power output. Feed solutions of different salinities were also tested. A good matching was found between predictions and experiments for a wide range of inlet concentrations, flow rates and feed temperatures. Optimal feed conditions, for the adopted system geometry and membranes, have been found employing brackish water (0.08-0.1 M NaCl) as dilute and brine (4.5-5 M NaCl) as concentrate to generate the highest power density at 40\ub0C temperature.
The model can be used to explore the full potential of the RED technology, especially for any investigation regarding the future scale-up of the process
Revisão de Toechorychus Townes (Hymenoptera, Ichneumonidae, Cryptinae)
O gênero Neotropical Toechorychus Townes é revisado e cladisticamente definido; 302 espécimes de 14 coleções foram examinados; 40 espécies são reconhecidas, das quais 35 são descritas como novas: T. sp. nov. 1, T. sp. nov. 2, T. sp. nov. 3, T. sp. nov. 4, T. sp. nov. 5, T. sp. nov. 6, T. sp. nov. 7, T. sp. nov. 8, T. sp. nov. 9, T. sp. nov. 10, T. sp. nov. 11, T. sp. nov. 12, T. sp. nov. 13, T. sp. nov. 14, T. sp. nov. 15, T. sp. nov. 16, T. sp. nov. 17, T. sp. nov. 18, T. sp. nov. 19, T. sp. nov. 20, T. sp. nov. 21, T. sp. nov. 22, T. sp. nov. 23, T. sp. nov. 24, T. sp. nov. 25, T. sp. nov. 26, T. sp. nov. 27, T. sp. nov. 28, T. sp. nov. 29, T. sp. nov. 30, T. sp. nov. 31, T. sp. nov. 32, T. sp. nov. 33, T. sp. nov. 34, T. sp. nov. 35. As demais espécies válidas são: T. abactus (Cresson), T. albimaculatus (Taschenberg), T. brevicaudis (Szépligeti), T. cassunungae (Brauns), T. stramineus (Taschenberg). O gênero pode ser reconhecido pela carena epicnemial geralmente não alcançando mais do que 0.3 da distância até a proeminência subtegular; sulco apical em forma de V presente na valva dorsal do ovipositor, anteriormente aos dentes apicais da valva ventral; presença de uma compressão subapical no ovipositor; bainha do ovipositor cerca de 0.1 tão longa quanto a tíbia posterior; e margem dorsal do pronoto fortemente inchada. Uma chave de identificação para todas as espécies conhecidas de Toechorychus, descrições de todas as espécies válidas, e análises filogenéticas são fornecidas, bem como ilustrações, e informações de distribuição para cada espécie. Registros de hospedeiro publicados foram compilados e três registros novos são fornecidos: T. albimaculatus é parasitóide de Mischocyttarus drewseni (Saussure) (Vespidae, Polistinae) novo registro; T. stramineus é parasitóide de M. basimacula (Cameron) novo registro; e T. sp. nov. 25 é parasitóide de M. collarellus Richards novo registro. Um Neótipo é designado para T. cassunungae. O gênero é provavelmente mais proximamente relacionado a Lymeon Föster e Acerastes Cushman
Simultaneous recording of electrical and metabolic activity of cardiac cells in vitro using an organic charge modulated field effect transistor array
In vitro electrogenic cells monitoring is an important objective in several scientific and technological fields, such as electrophysiology, pharmacology and brain machine interfaces, and can represent an interesting opportunity in other translational medicine applications. One of the key aspects of cellular cultures is the complexity of their behavior, due to the different kinds of bio-related signals, both chemical and electrical, that characterize these systems. In order to fully understand and exploit this extraordinary complexity, specific devices and tools are needed. However, at the moment this important scientific field is characterized by the lack of easy-to-use, low-cost devices for the sensing of multiple cellular parameters. To the aim of providing a simple and integrated approach for the study of in vitro electrogenic cultures, we present here a new solution for the monitoring of both the electrical and the metabolic cellular activity. In particular, we show here how a particular device called Micro Organic Charge Modulated Array (MOA) can be conveniently engineered and then used to simultaneously record the complete cell activity using the same device architecture. The system has been tested using primary cardiac rat myocytes and allowed to detect the metabolic and electrical variations thar occur upon the administration of different drugs. This first example could lay the basis for the development of a new generation of multi-sensing tools that can help to efficiently probe the multifaceted in vitro environment
Morphological and molecular characterization of two gastrointestinal parasites in Mustelus mustelus (Linnaeus, 1758) from Adriatic Sea
Specimens of common smooth-hound, Mustelus mustelus, fished as bycatch in the Northwestern Adriatic Sea, were
subjected to a complete parasitological examination. Parasites were processed for morphological and morphometric
analyses aimed at identifying them to the species level. Parasite identity was confirmed through amplification and
sequencing of 28S rDNA. The nematode Acanthocheilus rotundatus was recovered from the stomach and the proximal
intestine, while the cestode Calliobothrium verticillatum was collected from the spiral valve. Our results confirm the
occurrence of C. verticillatum in M. mustelus from the Mediterranean Sea and provide the first sequence data of A.
rotundatus from the same area. Updated knowledge on the parasite fauna of M. mustelus from Adriatic Sea contributes to elucidating aspects of the ecology, biology and health status of elasmobranchs from the Mediterranean Sea, providing
useful information for their proper management and conservation
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