The ionizing sources of luminous compact HII regions in the RCW106 and RCW122 clouds

Given the rarity of young O star candidates, compact HII regions embedded in dense molecular cores continue to serve as potential sites to peer into the details of high-mass star formation. To uncover the ionizing sources of the most luminous and compact HII regions embedded in the RCW106 and RCW122 giant molecular clouds, known to be relatively nearby (2-4 kpc) and isolated, thus providing an opportunity to examine spatial scales of a few hundred to a thousand AU in size. High spatial resolution (0.3"), mid-infrared spectra (R=350), including the fine structure lines [ArIII] and [NeII], were obtained for four luminous compact HII regions, embedded inside the dense cores within the RCW106 and RCW122 molecular cloud complexes. At this resolution, these targets reveal point-like sources surrounded by nebulosity of different morphologies, uncovering details at spatial dimensions of <1000AU. The point-like sources display [ArIII] and [NeII] lines - the ratios of which are used to estimate the temperature of the embedded sources. The derived temperatures are indicative of mid-late O type objects for all the sources with [ArIII] emission. Previously known characteristics of these targets from the literature, including evidence of disk or accretion suggest that the identified sources may grow more to become early-type O stars by the end of the star formation process

Future dynamics in f(R) theories

The $f(R)$ gravity theories provide an alternative way to explain the current cosmic acceleration without invoking dark energy matter component. However, the freedom in the choice of the functional forms of $f(R)$ gives rise to the problem of how to constrain and break the degeneracy among these gravity theories on theoretical and/or observational grounds. In this paper to proceed further with the investigation on the potentialities, difficulties and limitations of $f(R)$ gravity, we examine the question as to whether the future dynamics can be used to break the degeneracy between $f(R)$ gravity theories by investigating the future dynamics of spatially homogeneous and isotropic dust flat models in two $f(R)$ gravity theories, namely the well known $f(R) = R + \alpha R^{n}$ gravity and another by A. Aviles et al., whose motivation comes from the cosmographic approach to $f(R)$ gravity. To this end we perform a detailed numerical study of the future dynamic of these flat model in these theories taking into account the recent constraints on the cosmological parameters made by the Planck team. We show that besides being powerful for discriminating between $f(R)$ gravity theories, the future dynamics technique can also be used to determine the fate of the Universe in the framework of these $f(R)$ gravity theories. Moreover, there emerges from our numerical analysis that if we do not invoke a dark energy component with equation-of-state parameter $\omega < -1$ one still has dust flat FLRW solution with a big rip, if gravity deviates from general relativity via $f(R) = R + \alpha R^n$. We also show that FLRW dust solutions with $f''<0$ do not necessarily lead to singularity.Comment: 12 pages, 8 figures. V2: Generality and implications of the results are emphasized, connection with the recent literature improved, typos corrected, references adde

Autumn Root Reserves of Lucerne Affected Shoot Yields During the Following Spring

Frequent grazing affects shoot yield of lucerne (Medicago sativa L.) by limiting radiation interception (Teixeira et al., 2005b) and the accumulation of endogenous reserves (C and N) in perennial storage organs like crowns and taproots (Teixeira et al., 2005a). In temperate regions, the impact of low level of perennial reserves is particularly evident during early-spring, when lucerne regrowth resumes after an overwintering period. The analysis of lucerne yield can be fragmented into its yield components of plant population, shoots per plant and yield per shoot (Volenec et al., 1987). The objective of this research was to quantify the impact of limiting levels of perennial reserves, caused by frequent defoliations, on lucerne early-spring yield and determine the sensitivity of yield components to treatments

Lumbar paraspinal intramuscular myxoma: A case report

Background: With an estimated incidence of about 1 case/million patients, paravertebral intramuscular myxomas represent a rare cause of lumbar pain. Rather, they typically occur in the heart and in bone tissues. Case description: A 64-year-old female presented with a protracted course of nocturnal lumbar pain that radiated to the anterior aspect of the right thigh accompanied by numbness. She reported a slow-growing right paramedian lumbar mass in the previous months. The magnetic resonance (MR) showed a right lumbar paravertebral intramuscular mass at the L3 level (i.e., 70 × 50 mm) that had well-defined margins, and markedly enhanced with gadolinium. Following gross total "en bloc" tumor resection, the patient fully recovered. Pathologically, the myofibroblastic lesion proved to be an intramuscular myxoma without malignant changes. Conclusion: A 64-year-old female presented with a slow-growing MR-documented right paramedian lumbar L3 mass responsible for proximal right-thigh numbness. Following "en bloc" gross total removal of the benign intramuscular myxoma, the patient was asymptomatic.info:eu-repo/semantics/publishedVersio

Diagnosing numerical Cherenkov instabilities in relativistic plasma simulations based on general meshes

Numerical Cherenkov radiation (NCR) or instability is a detrimental effect frequently found in electromagnetic particle-in-cell (EM-PIC) simulations involving relativistic plasma beams. NCR is caused by spurious coupling between electromagnetic-field modes and multiple beam resonances. This coupling may result from the slow down of poorly-resolved waves due to numerical (grid) dispersion and from aliasing mechanisms. NCR has been studied in the past for finite-difference-based EM-PIC algorithms on regular (structured) meshes with rectangular elements. In this work, we extend the analysis of NCR to finite-element-based EM-PIC algorithms implemented on unstructured meshes. The influence of different mesh element shapes and mesh layouts on NCR is studied. Analytic predictions are compared against results from finite-element-based EM-PIC simulations of relativistic plasma beams on various mesh types.Comment: 31 pages, 20 figure

Microscopy studies in support of dating of mortars of historical buildings

Fundação das Universidades PortuguesasMinisterio de Ciencia e InnovaciónFundação para a Ciência e a Tecnologia (FCT

Caracterização de Latossolo Amarelo no município de Parintins: Estado do Amazonas: alguns atributos físicos, químicos e hídricos.

O presente estudo teve por objetivo caracterizar um Latossolo predominante na paisagem da Serra de Parintins com o intuito de contribuir para uma melhor utilização do solo pelos produtores, considerando como padrão solo sob floresta e áreas cultivadas