Star formation in shocked cluster spirals and their tails

Recent observations of ram pressure stripped spiral galaxies in clusters revealed details of the stripping process, i.e., the truncation of all interstellar medium (ISM) phases and of star formation (SF) in the disk, and multiphase star-forming tails. Some stripped galaxies, in particular in merging clusters, develop spectacular star-forming tails, giving them a jellyfish-like appearance. In merging clusters, merger shocks in the intra-cluster medium (ICM) are thought to have overrun these galaxies, enhancing the ambient ICM pressure and thus triggering SF, gas stripping and tail formation. We present idealised hydrodynamical simulations of this scenario, including standard descriptions for SF and stellar feedback. To aid the interpretation of recent and upcoming observations, we focus on particular structures and dynamics in SF patterns in the remaining gas disk and in the near tails, which are easiest to observe. The observed jellyfish morphology is qualitatively reproduced for, both, face-on and edge-on stripping. In edge-on stripping, the interplay between the ICM wind and the disk rotation leads to asymmetries along the ICM wind direction and perpendicular to it. The apparent tail is still part of a highly deformed gaseous and young stellar disk. In both geometries, SF takes place in knots throughout the tail, such that the stars in the tails show no ordered age gradients. Significant SF enhancement in the disk occurs only at radii where the gas will be stripped in due course.Comment: 6 pages, submitted to MNRAS Letter

Metal mixing by buoyant bubbles in galaxy clusters

Using a series of three-dimensional, hydrodynamic simulations on an adaptive grid, we have performed a systematic study on the effect of bubble-induced motions on metallicity profiles in clusters of galaxies. In particular, we have studied the dependence on the bubble size and position, the recurrence times of the bubbles, the way these bubbles are inflated and the underlying cluster profile. We find that in hydrostatic cluster models, the resulting metal distribution is very elongated along the direction of the bubbles. Anisotropies in the cluster or ambient motions are needed if the metal distribution is to be spherical. In order to parametrise the metal transport by bubbles, we compute effective diffusion coefficients. The diffusion coefficients inferred from our simple experiments lie at values of around $\sim 10^{29}$ cm$^2$s$^{-1}$ at a radius of 10 kpc. The runs modelled on the Perseus cluster yield diffusion coefficients that agree very well with those inferred from observations.Comment: 17 pages, 12 figures. Accepted by MNRA

Deese-roediger-McDermott paradigm: Effect of previous recall and type of memory task

Pretendeu-se averiguar se a activação dos itens críticos no paradigma de Deese-Roediger-McDermott também ocorreria numa tarefa de completamento. Para analisar a contaminação explícita explorámos a existência de resultados dissociados em função da manipulação do nível de processamento. Na tarefa de completamento, a primação semântica foi estatisticamente superior à primação directa. A ausência do efeito do nível de processamento demonstra que o teste foi de memória implícita. Também avaliámos o impacto de uma tarefa de evocação numa tarefa de memória posterior. Verificámos que a evocação prévia anulou o efeito do nível de processamento na tarefa de reconhecimento. Na tarefa de completamento de inícios de palavras, o incremento de inícios de palavras completados com associados só foi expressivo quando as palavras foram codificadas superficialmente.This study aimed to verifj whether lhe activation ofcritical items in the Deese-Roediger-McDermott paradigm ofproducing false memories could also occur in the word stem completion task. The finding that lhe levei ofprocessing did not seem to have any effect on the word stem completion task supported lhe conclusion that the stem completion task was in fact an irnplicit memory test. The impact of a previous recali in a followng memory task was also evaluated. The results indicated that lhe previous recall inhibited the effect ofthe processing levei in lhe recognition task. In the word stem completion task lhe increase ofstems completed with associates was only relevam when words were encoded superficialiy.(undefined

A Self-Reference False Memory Effect in the DRM Paradigm: Evidence from Eastern and Western Samples

It is well established that processing information in relation to oneself (i.e., selfreferencing) leads to better memory for that information than processing that same information in relation to others (i.e., other-referencing). However, it is unknown whether self-referencing also leads to more false memories than other-referencing. In the current two experiments with European and East Asian samples, we presented participants the Deese-Roediger/McDermott (DRM) lists together with their own name or other people’s name (i.e., “Trump” in Experiment 1 and “Li Ming” in Experiment 2). We found consistent results across the two experiments; that is, in the self-reference condition, participants had higher true and false memory rates compared to those in the other-reference condition. Moreover, we found that selfreferencing did not exhibit superior mnemonic advantage in terms of net accuracy compared to other-referencing and neutral conditions. These findings are discussed in terms of theoretical frameworks such as spreading activation theories and the fuzzytrace theory. We propose that our results reflect the adaptive nature of memory in the sense that cognitive processes that increase mnemonic efficiency may also increase susceptibility to associative false memories

Greater priming for previously distracting information in young than older adults when suppression is ruled out

The use of previously distracting information on memory tests with indirect instructions is usually age-equivalent, while young adults typically show greater explicit memory for such information. This could reflect qualitatively distinct initial processing (encoding) of distracting information by younger and older adults, but could also be caused by greater suppression of such information by younger adults on tasks with indirect instructions. In Experiment 1, young and older adults read stories containing distracting words, which they ignored, before studying a list of words containing previously distracting items for a free recall task. Half the participants were informed of the presence of previously distracting items in the study list prior to recall (direct instruction), and half were not (indirect instruction). Recall of previously distracting words was age-equivalent in the indirect condition, but young adults recalled more distracting words in the direct condition. In Experiment 2, participants performed the continuous identification with recognition task, which captures a measure of perceptual priming and recognition on each trial, and is immune to suppression. Priming and recognition of previously distracting words was greater in younger than older adults, suggesting that the young engage in more successful suppression of previously distracting information on tasks in which its relevance is not overtly signaled

Jupiter's X-ray and EUV auroras monitored by Chandra, XXM-Newton, and Hisaki satellite

Jupiter's X-ray auroral emission in the polar cap region results from particles which have undergone strong field-aligned acceleration into the ionosphere. The origin of precipitating ions and electrons and the time variability in the X-ray emission are essential to uncover the driving mechanism for the high-energy acceleration. The magnetospheric location of the source field line where the X-ray is generated is likely affected by the solar wind variability. However, these essential characteristics are still unknown because the long-term monitoring of the X-rays and contemporaneous solar wind variability has not been carried out. In April 2014, the first long-term multiwavelength monitoring of Jupiter's X-ray and EUV auroral emissions was made by the Chandra X-ray Observatory, XMM-Newton, and Hisaki satellite. We find that the X-ray count rates are positively correlated with the solar wind velocity and insignificantly with the dynamic pressure. Based on the magnetic field mapping model, a half of the X-ray auroral region was found to be open to the interplanetary space. The other half of the X-ray auroral source region is magnetically connected with the prenoon to postdusk sector in the outermost region of the magnetosphere, where the Kelvin-Helmholtz (KH) instability, magnetopause reconnection, and quasiperiodic particle injection potentially take place. We speculate that the high-energy auroral acceleration is associated with the KH instability and/or magnetopause reconnection. This association is expected to also occur in many other space plasma environments such as Saturn and other magnetized rotators

Investigating the influence of professor characteristics on student satisfaction and dissatisfaction: a comparative study

This research uses the Kano model of satisfaction to investigate professor characteristics that create student satisfaction as well as those attributes that can cause their dissatisfaction. Kano questionnaires were handed out to 104 undergraduate students at a university in the Southwest and to 147 undergraduate students at a university in the Midwest of the United States. The two resulting Kano maps show the same delighting attributes although other satisfaction attributes are also similar. The findings reveal the importance of the personality of professors and the characteristics of professors that (a) are desired by students, (b) are not desired by students, (c) affect student satisfaction the most, and (d) affect satisfaction the least. The results also demonstrate how professors and universities can focus attention on those attributes most likely to influence satisfaction. No attributes of professors are classified as basic or taken for granted factors by students, although three attributes are excitement factors that have the potential to delight students. The findings illustrate that there is a set of multiple attributes that professors need to possess for satisfying student–professor classroom service encounters. Student populations appear to show strong similarities in their preferences for characteristics of professors that lead to satisfaction and dissatisfaction outcomes

Ram pressure stripping of the multiphase ISM and star formation in the Virgo spiral galaxy NGC 4330

It has been shown that the Virgo spiral galaxy NGC 4330 shows signs of ongoing ram pressure stripping in multiple wavelengths: at the leading edge of the interaction, the Halpha and dust extinction curve sharply out of the disk; on the trailing side, a long Halpha/UV tail has been found which is located upwind of a long HI tail. We complete the multiwavelength study with IRAM 30m HERA CO(2-1) and VLA 6 cm radio continuum observations of NGC 4330. The data are interpreted with the help of a dynamical model including ram pressure and, for the first time, star formation. Our best-fit model reproduces qualitatively the observed projected position, radial velocity of the galaxy, the molecular and atomic gas distribution and velocity field, and the UV distribution in the region where a gas tail is present. However, the observed red UV color on the windward side is currently not reproduced by the model. Based on our model, the galaxy moves to the north and still approaches the cluster center with the closest approach occurring in ~100 Myr. In contrast to other Virgo spiral galaxies affected by ram pressure stripping, NGC 4330 does not show an asymmetric ridge of polarized radio continuum emission. We suggest that this is due to the relatively slow compression of the ISM and the particular projection of NGC 4330. The observed offset between the HI and UV tails is well reproduced by our model. Since collapsing and starforming gas clouds decouple from the ram pressure wind, the UV-emitting young stars have the angular momentum of the gas at the time of their creation. On the other hand, the gas is constantly pushed by ram pressure. The reaction (phase change, star formation) of the multiphase ISM (molecular, atomic, ionized) to ram pressure is discussed in the framework of our dynamical model.Comment: 18 pages, 17 figures, accepted by A&