A granular approach to source trustworthiness for negative trust assessment

The problem of determining what information to trust is crucial in many contexts that admit uncertainty and polarization. In this paper, we propose a method to systematically reason on the trustworthiness of sources. While not aiming at establishing their veracity, the metho

Neutron-antineutron Oscillations in the Trapping Box

We have reexamined the problem of $n-\bar n$ oscillations for ultra-cold neutrons (UCN) confined within a trap. We have shown that the growth of the $\bar n$ component with time is to a decent accuracy given by $P(\bar n)= \epsilon^2_{n\bar n} t_Lt,$ where $\epsilon_{n\bar n}$ is the mixing parameter, $t_L\sim 1$ sec in the neutron propagation time between subsequent collisions with the trap walls. Possible corrections to this law and open questions are discussed.Comment: 11 pages, LaTeX2

Conjuntos de bases Gaussianas de qualidade quádrupla zeta de valência para os átomos de Rb até Xe.

Conjuntos de bases para todos elétrons de contração segmentada de qualidade quádrupla zeta de valência mais funções de polarização (QZP) para os elementos Rb-Xe foram construídos para serem usados em conjunção com os Hamiltonianos não relativístico e Douglas-Kroll-Hess (DKH). O conjunto QZP-DKH foi obtido a partir do conjunto de bases original QZP, isto é, os valores dos coeficientes de contração foram reotimizados utilizando o Hamiltoniano relativístico DKH. Isto estende trabalhos anteriores de conjunto de bases de contração segmentada QZ para os átomos H-Kr. Ao nível de teoria Coupled Cluster, a convergência de energia de ionização atômica bem como de constantes espectroscópicas moleculares em função do tamanho do conjunto de bases foi examinada. Uma melhora adicional nas constantes espectroscópicas foi obtida aplicando correções devido à correlação caroço-valência e efeito spin-órbita. Isso conduz a estimativas de constantes espectroscópicas de várias moléculas diatômicas em fase gasosa. Verifica-se que os resultados para os comprimentos de ligação, energias de dissociação e frequências vibracionais harmônicas experimentais e teóricos de referência podem ser bem reproduzidos com o conjunto QZPDKH. Conjunto de bases Gaussianas aumentado de qualidade quádrupla zeta de valência mais funções de polarização para os átomos de Rb e de Y até Xe foi apresentado. Ele foi construído a partir do conjunto não aumentado para todos os elétrons pela adição de funções difusas (de simetrias s, p, d, f, g e h), que foram optimizadas para os estados fundamentais dos ânions. A partir desse conjunto, momento de dipolo elétrico e polarizabilidades Hartree-Fock, teoria de perturbação de Møller-Plesset de segunda ordem e teoria do funcional da densidade para uma amostra de moléculas tão bem como para o aglomerado Agn (n ≤ 4) foram calculados e comparados com valores teórico e experimental disponíveis na literatura

The Rise Times of High and Low Redshift Type Ia Supernovae are Consistent

We present a self-consistent comparison of the rise times for low- and high-redshift Type Ia supernovae. Following previous studies, the early light curve is modeled using a t-squared law, which is then mated with a modified Leibundgut template light curve. The best-fit t-squared law is determined for ensemble samples of low- and high-redshift supernovae by fitting simultaneously for all light curve parameters for all supernovae in each sample. Our method fully accounts for the non-negligible covariance amongst the light curve fitting parameters, which previous analyses have neglected. Contrary to Riess et al. (1999), we find fair to good agreement between the rise times of the low- and high-redshift Type Ia supernovae. The uncertainty in the rise time of the high-redshift Type Ia supernovae is presently quite large (roughly +/- 1.2 days statistical), making any search for evidence of evolution based on a comparison of rise times premature. Furthermore, systematic effects on rise time determinations from the high-redshift observations, due to the form of the late-time light curve and the manner in which the light curves of these supernovae were sampled, can bias the high-redshift rise time determinations by up to +3.6/-1.9 days under extreme situations. The peak brightnesses - used for cosmology - do not suffer any significant bias, nor any significant increase in uncertainty.Comment: 18 pages, 4 figures, Accepted for publication in the Astronomical Journal. Also available at http://www.lbl.gov/~nugent/papers.html Typos were corrected and a few sentences were added for improved clarit

Atributos anatômicos de lâminas foliares de Paspalum spp.

Gramíneas do gênero Paspalum spp. apresentam alto potencial para o melhoramento genético, devido à sua grande variabilidade genética. Este estudo, conduzido na Universidade Federal da Grande Dourados, teve como objetivo avaliar atributos anatômicos de lâminas foliares de Paspalum spp. (P. malacophyllum - P30, P. guenoarum - P65, P. glaucescens - P114, P. spp.- Pl16, P. spp. - P127, P. guenoarum - P148, P. regnellii - P191 e uma cultivar comercial- P. alralum cv. Pojuca). Utilizou-se o delineamento de blocos ao acaso, oito genótipos e quatro repetições. Os fragmentos das lâminas foram fixados em F AA e após efetuou-se o preparo histológico. Alta variabilidade entre os genótipos foi observada quanto à proporção e arranjo de tecidos, e presença de tanino condensado na epiderme. Dos caracteres avaliados a presença de estrutura girder, foi a que mais discriminou os genótipos quanto ao potencial qualitativo das lâminas. Estudos devem ser conduzidos para verificar o efeito do tanino condensado, presente na epiderme, no potencial qualitativo dos genótipos

Free electron lifetime achievements in Liquid Argon Imaging TPC

A key feature for the success of the liquid Argon imaging TPC (LAr-TPC) technology is the industrial purification against electro-negative impurities, especially Oxygen and Nitrogen remnants, which have to be continuously kept at an exceptionally low level by filtering and recirculating liquid Argon. Improved purification techniques have been applied to a 120 liters LAr-TPC test facility in the INFN-LNL laboratory. Through-going muon tracks have been used to determine the free electron lifetime in liquid Argon against electro-negative impurities. The short path length here observed (30 cm) is compensated by the high accuracy in the observation of the specific ionization of cosmic ray muons at sea level as a function of the drift distance. A free electron lifetime of (21.4+7.3-4.3) ms, namely > 15.8 ms at 90 % C.L. has been observed over several weeks under stable conditions, corresponding to a residual Oxygen equivalent of about 15 ppt (part per trillion). At 500 V/cm, the free electron speed is 1.5 m/ms. In a LAr-TPC a free electron lifetime in excess of 15 ms corresponds for instance to an attenuation of less than 15 % after a drift path of 5 m, opening the way to the operation of the LAr-TPC with exceptionally long drift distances.Comment: 15 pages, 10 figures; Accepted for publication in JINS

The design and commissioning of the MICE upstream time-of-flight system

In the MICE experiment at RAL the upstream time-of-flight detectors are used for particle identification in the incoming muon beam, for the experiment trigger and for a precise timing (sigma_t ~ 50 ps) with respect to the accelerating RF cavities working at 201 MHz. The construction of the upstream section of the MICE time-of-flight system and the tests done to characterize its individual components are shown. Detector timing resolutions ~50-60 ps were achieved. Test beam performance and preliminary results obtained with beam at RAL are reported.Comment: accepted on Nuclear Instruments and Methods

CPT violation and particle-antiparticle asymmetry in cosmology

General features of generation of the cosmological charge asymmetry in CPT non-invariant world are discussed. If the effects of CPT violation manifest themselves only in mass differences of particles and antiparticles, the baryon asymmetry of the universe hardly can be explained solely by breaking of CPT invariance. However, CPT non-invariant theories may lead to a new effect of distorting the usual equilibrium distributions. If this takes place, CPT violation may explain the baryon asymmetry of the universe.Comment: 7 pages, no figures. Submitted to a special issue of Yadernaya Fizika (Physics of Atomic Nuclei) dedicated to 80th birthday of L.B. Okun. Three references are adde

Maastrichtian microfossils of the Shallow Marine Umir Formation, Northeastern Colombia

During the Late Cretaceous, northern South America was characterized by broad epicontinental seas, with variable surface productivity and changing bottom-water oxygenation. Global sea-level fluctuations and local tectonic shifts caused their disappearance in the latest Cretaceous. We present an integrated micropaleontological and geochemical study of a section comprising the Umir Formation and its lower stratigraphic contact with the La Luna Formation, in the Middle Magdalena Valley, northeastern Colombia. Foraminiferal assemblages were moderately diverse and mainly dominated by benthic taxa, characterizing the biozones Siphogenerinoides bramlettei and Ammobaculites colombiana (Maastrichtian). Planktonic foraminiferal assemblages were less diversified, being species assigned to Heterohelicidae and scarce keeled forms (Globotruncana spp.) the most recurrent taxa. Ostracod recovery was very scarce, and we could only identify the genus Actinocythereis. In contrast, calcareous nannofossil assemblages were moderately diversified along the section, and composed of typical Late Cretaceous low-latitude taxa such as Micula staurophora, Cribrosphaerella ehrenbergii, Gartnerago segmentatum. The identified microfossils indicate a transition from middle-inner shelf conditions, with moderately oxygenated bottom waters within the La Luna Formation, to a shallower marine setting within the Umir Formation. This interpretation is supported by Sr/Ba and log(Fe/Ca) ratios measured in bulk sediment, which indicate increased continental runoff and terrigenous input in the upper part of the section. Moreover, a significant biotic turnover was identified at the base of the section, suggesting the presence of a xenoconformity at the La Luna-Umir contact, which has been previously described and proposed as a regional stratigraphic feature. El Cretácico Tardío del norte de Sudamérica estuvo dominado por mares epicontinentales extensos, con fluctuaciones de la productividad superficial y oxigenación del agua de fondo. Cambios en los regímenes tectónicos locales y descensos globales en el nivel del mar, llevaron a la desaparición de dichos ambientes hacia fines del Cretácico. Presentamos un estudio micropaleontológico y geoquímico integrado de una sección de la Formación Umir y su contacto basal con la Formación La Luna en el Valle Medio del Magdalena, noreste de Colombia. Las asociaciones de foraminíferos fueron moderadamente diversas y estuvieron dominadas por formas bentónicas que definen las biozonas de asociación locales Siphogenerinoides bramlettei y Ammobaculites colombiana (Maastrichtiano). Las formas planctónicas, menos diversas, incluyeron ejemplares de Heterohelicidae y escasas formas quilladas (Globotruncana spp.). El registro de ostrácodos fue muy escaso, sólo pudimos reconocer al género Actinocythereis. En contraste, las asociaciones de nanofósiles calcáreos fueron moderadamente diversas y comprendieron formas típicas de bajas latitudes del Cretácico Tardío como Micula staurophora, Cribrosphaerella ehrenbergii, Gartnerago segmentatum. Las asociaciones de microfósiles indican una transición de condiciones de plataforma media-interna, moderadamente oxigenada en la Formación La Luna, a un ambiente más somero en la Formación Umir. Esta interpretación es corroborada por las relaciones de Sr/Ba y log(Fe/Ca) del sedimento que indican un aumento en la escorrentía continental y el aporte de terrígenos hacia la parte superior de la sección. De igual forma, la variación significativa en las asociaciones de microfósiles hacia la base sugiere la presencia de una xenoconformidad en el contacto La Luna-Umir, que fue previamente reportada como de carácter regional

Computable trustworthiness ranking of medical experts in Italy during the SARS-CoV-19 pandemic

Source trustworthiness can help discerning reliable and truthful information. We offer a computable model for the dynamic assessment of sources trustworthiness based on their popularity, knowledge-ability, and reputation. We apply it to the debate among medical experts in Italy during three distinct phases of the SARS-CoV-19 pandemic, and validate it against a dataset of newspaper articles. The model shows promising results in the analysis of expert debates their impact on public opinion