Morphology of galaxies with quiescent recent assembly history in a Lambda-CDM universe

The standard disc formation scenario postulates that disc forms as the gas cools and flows into the centre of the dark matter halo, conserving the specific angular momentum. Major mergers have been shown to be able to destroy or highly perturb the disc components. More recently, the alignment of the material that is accreted to form the galaxy has been pointed out as a key ingredient to determine galaxy morphology. However, in a hierarchical scenario galaxy formation is a complex process that combines these processes and others in a non-linear way so that the origin of galaxy morphology remains to be fully understood. We aim at exploring the differences in the formation histories of galaxies with a variety of morphology, but quite recent merger histories, to identify which mechanisms are playing a major role. We analyse when minor mergers can be considered relevant to determine galaxy morphology. We also study the specific angular momentum content of the disc and central spheroidal components separately. We used cosmological hydrodynamical simulations that include an effective, physically motivated supernova feedback that is able to regulate the star formation in haloes of different masses. We analysed the morphology and formation history of a sample of 15 galaxies of a cosmological simulation. We performed a spheroid-disc decomposition of the selected galaxies and their progenitor systems. The angular momentum orientation of the merging systems as well as their relative masses were estimated to analyse the role played by orientation and by minor mergers in the determination of the morphology. We found the discs to be formed by conserving the specific angular momentum in accordance with the classical disc formation model. The specific angular momentum of the stellar central spheroid correlates with the dark matter halo angular momentum and determines a power law. AbridgedComment: 10 pages, 9 figures, A&A in pres

Metallicity dependence of HMXB populations

High-mass X-ray binaries (HMXBs) might have contributed a non-negligible fraction of the energy feedback to the interstellar and intergalactic media at high redshift, becoming important sources for the heating and ionization history of the Universe. However, the importance of this contribution depends on the hypothesized increase in the number of HMXBs formed in low-metallicity galaxies and in their luminosities. In this work we test the aforementioned hypothesis, and quantify the metallicity dependence of HMXB population properties. We compile from the literature a large set of data on the sizes and X-ray luminosities of HMXB populations in nearby galaxies with known metallicities and star formation rates. We use Bayesian inference to fit simple Monte Carlo models that describe the metallicity dependence of the size and luminosity of the HMXB populations. We find that HMXBs are typically ten times more numerous per unit star formation rate in low-metallicity galaxies (12 + log(O/H) < 8, namely < 20% solar) than in solar-metallicity galaxies. The metallicity dependence of the luminosity of HMXBs is small compared to that of the population size. Our results support the hypothesis that HMXBs are more numerous in low-metallicity galaxies, implying the need to investigate the feedback in the form of X-rays and energetic mass outflows of these high-energy sources during cosmic dawn.Comment: 9 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

Total Intravenous Anesthesia for Neurosurgical Procedures in Narcoleptic Patients: Two Case Reports

INTRODUCTION: Narcoleptic patients may be at increased risk of prolonged emergence, postoperative hypersomnia, apneic episodes, and sleep paralysis after general anesthesia. Modafinil is the first-line treatment, however, the implication it has on general anesthesia is not clear. This report present 2 cases of narcoleptic patients medicated with modafinil that were submitted to total intravenous anesthesia for neurosurgical procedures. CASE PRESENTATION: Informed consent was obtained from both patients. Clinical information was obtained from patients' interviews and medical records. Intraoperative data was collected using Datex Ohmeda, Bispectral index, Entropy, and LiDCO rapid monitors, and exported to excel sheets to allow its analysis. Both patients maintained modafinil on the day of surgery and were not administered sedative premedication. Propofol was administered by bolus during induction of anesthesia. In one of the patients, the predicted cerebral concentration of propofol required for loss of consciousness was high. Anesthesia was maintained with remifentanil and propofol by target controlled infusion and titrated according to bispectral index (BIS), entropy, and analgesia nociception index (ANI). During the surgical procedure, the patients did not require vasopressors. Emergence from anesthesia was very fast and no narcoleptic event occurred postoperatively. CONCLUSIONS: Sedative premedication should be avoided and the use of short-acting anesthetic agents, such as propofol and remifentanil through target-controlled infusion most likely improves titration of anesthesia. The continuation of modafinil preoperatively might have contributed to the rapid emergence, yet, might also have been responsible for the high cerebral concentration of propofol that was required for loss of consciousness in one of the patients.info:eu-repo/semantics/publishedVersio

Runoff at the micro-plot and slope scale following wildfire, central Portugal

Through their effects on soil properties and vegetation/litter cover, wildfires can strongly enhance overland flow generation and accelerate soil erosion [1] and, thereby, negatively affect land-use sustainability as well as downstream aquatic and flood zones. Wildfires are a common phenomenon in present-day Portugal, devastating in an average year some 100.000 ha of forest and woodlands and in an exceptional year like 2003 over 400.000 ha. There therefore exists a clear need in Portugal for a tool that can provide guidance to post-fire land management by predicting soil erosion risk, on the one hand, and, on the other, the mitigation effectiveness of soil conservation measures. Such a tool has recently been developed for the Western U.S.A. [3: ERMiT] but its suitability for Portuguese forests will need to be corroborated by field observations. Testing the suitability of existing erosion models in recently burned forest areas in Portugal is, in a nutshell, the aim of the EROSFIRE projects. In the first EROSFIRE project the emphasis was on the prediction of erosion at the scale of individual hill slopes. In the ongoing EROSFIRE-II project the spatial scope is extended to include the catchment scale, so that also the connectivity between hill slopes as well as channel and road processes are being addressed. Besides ERMiT, the principal models under evaluation for slope-scale erosion prediction are: (i) the variant of USLE [4] applied by the Portuguese Water Institute after the wildfires of 2003; (ii) the Morgan–Morgan–Finney model (MMF) [5]; (iii) MEFIDIS [6]. From these models, MEFIDIS and perhaps MMF will, after successful calibration at the slope scale, also be applied for predicting catchment-scale sediment yields of extreme events

Runoff and erosion at the micro-plot and slope scale in a small burnt catchment, central Portugal

Wildfires can have important impacts on hydrological processes and soil erosion in forest catchments, due to the destruction of vegetation cover and changes to soil properties. However, the processes involved are non-linear and not fully understood. This has severely limited the understanding on the impacts of wildfires, especially in the up-scaling from hillslopes to catchments; in consequence, current models are poorly adapted for burnt forest conditions. The objective of this presentation is to give an overview of the hydrological response and sediment yield from the micro-plot to slope scale, in the first year following a wildfire (2008/2009) that burnt an entire catchment nearby the Colmeal village, central Portugal. The overview will focus on three slopes inside the catchment, with samples including: • Runoff at micro-plot scale (12 bounded plots) and slope scale (12 open plots); • Sediments and Organic Matter loss at micro-plot scale (12 bounded plots) and slope scale (12 open plots plus 3 Sediment fences); • Rainfall and Soil moisture data; • Soil Water Repellency and Ground Cover data. The analysis of the first year following the wildfire clearly shows the complexity of runoff generation and the associated sediment transport in recently burnt areas, with pronounced differences between hillslopes and across spatial scales as well as with marked variations through time. This work was performed in the framework of the EROSFIRE-II project (PTDC/AGR-CFL/70968/2006) which has as overall aim to predict soil erosion risk in recently burnt forest areas, including common post-fire forest management practices; the project focuses on the simultaneous measurement of runoff and soil erosion at multiple spatial scales.The results to be presented in this session are expected to show how sediment is generated, transported and exported in the Colmeal watershed; and contribute to understand and simulate erosion processes in burnt catchments, including for model development and evaluation

Learning predictive cognitive maps with spiking neurons during behaviour and replays

The hippocampus has been proposed to encode environments using a representation that contains predictive information about likely future states, called the successor representation. However, it is not clear how such a representation could be learned in the hippocampal circuit. Here, we propose a plasticity rule that can learn this predictive map of the environment using a spiking neural network. We connect this biologically plausible plasticity rule to reinforcement learning, mathematically and numerically showing that it implements the TD-lambda algorithm. By spanning these different levels, we show how our framework naturally encompasses behavioral activity and replays, smoothly moving from rate to temporal coding, and allows learning over behavioral timescales with a plasticity rule acting on a timescale of milliseconds. We discuss how biological parameters such as dwelling times at states, neuronal firing rates and neuromodulation relate to the delay discounting parameter of the TD algorithm, and how they influence the learned representation. We also find that, in agreement with psychological studies and contrary to reinforcement learning theory, the discount factor decreases hyperbolically with time. Finally, our framework suggests a role for replays, in both aiding learning in novel environments and finding shortcut trajectories that were not experienced during behavior, in agreement with experimental data

The CWKB particle production and classical condensate in de Sitter spacetime

The complex time WKB approximation is an effective tool in studying particle production in curved spacetime. We use it in this work to understand the formation of classical condensate in expanding de Sitter spacetime. The CWKB leads to the emergence of thermal spectrum that depends crucially on horizons (as in de Sitter spacetime) or observer dependent horizons (as in Rindler spacetime). A connection is sought between the horizon and the formation of classical condensate. We concentrate on de Sitter spacetime and study the cosmological perturbation of $k=0$ mode with various values of $m/H_0$. We find that for a minimally coupled free scalar field for $m^2/H_0^2<2$, the one-mode occupation number grows more than unity soon after the physical wavelength of the mode crosses the Hubble radius and soon after diverges as $N(t)\sim O(1)[\lambda_{phys}(t)/{H_0^{-1}}]^{2\sqrt{\nu^2-1/4}}$, where $\nu\equiv (9/4 -m^2/{H_0^2})^{1/2}$. The results substantiates the previous works in this direction. We also find the correct oscillation and behaviour of $N(z)$ at small $z$ from a single expression using CWKB approximation for various values of $m/H_0$. We also discuss decoherence in relation to the formation of classical condensate. We also find that the squeezed state formalism and CWKB method give identical results.Comment: 19 pages, revtex, 5 figure

Targetability of hyaluronic acid nanogel to cancer cells: In vitro and in vivo studies

We have, in previous work developed, characterized and evaluated the biocompatibility of an engineered hyaluronic acid nanogel. Here we assess the targetability of a hyaluronic acid nanogel towards CD44 overexpressing cells, in vitro and in vivo. Results obtained by flow cytometry and confocal fluorescence microscopy shows that nanogel is greatly internalized by non-small cancer lung cells (A549 cells), that overexpress CD44 receptors. The biodistribution and tumor targetability of the nanogel labelled with a near-infrared (NIR) probe were performed, in mice, through a non-invasive imaging system. Results revealed nanogel high targetability towards an induced subcutaneous A549 tumor. Nanogels pharmacokinetics was evaluated also in healthy animals, and Alexa Fluor 680 labelled nanogel exhibited higher accumulation in liver, kidneys and skin. Also, a comparative biodistribution study was performed, using two NIR imaging probes, Cy5.5 and Alexa Fluor 680.The authors thank the FCT Strategic Project of UID/BIO/04469/ 2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124FEDER-027462) and the Project “BioHealth - Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. We would like to acknowledge also the support of FCT for the PhD grant reference SFRH/BD/61516/2009. We would also like to thank Bioimaging department on Molecular Medicine Institute (IMM) in Lisbon, namely Dr. José Rino and Dr. António Temudo. Also thank the animal facilities in IMM (Lisbon), specially Dra. Dolores Bonaparte and Dra. Joana Marques. Also, we would like to acknowledge the special contribution of Professor Fatima Baltazar in ICVS (Braga) for kindly grant us CFBE and A549 cell lines.info:eu-repo/semantics/publishedVersio