The Effects of radial inflow of gas and galactic fountains on the chemical evolution of M31

Galactic fountains and radial gas flows are very important ingredients in modeling the chemical evolution of galactic disks. Our aim here is to study the effects of galactic fountains and radial gas flows in the chemical evolution of the disk of M31. We adopt a ballistic method to study the effects of galactic fountains on the chemical enrichment of the M31 disk. We find that the landing coordinate for the fountains in M31 is no more than 1 kpc from the starting point, thus producing negligible effect on the chemical evolution of the disk. We find that the delay time in the enrichment process due to fountains is no longer than 100 Myr and this timescale also produces negligible effects on the results. Then, we compute the chemical evolution of the M31 disk with radial gas flows produced by the infall of extragalactic material and fountains. We find that a moderate inside-out formation of the disk coupled with radial flows of variable speed can very well reproduce the observed gradient. We discuss also the effects of other parameters such a threshold in the gas density for star formation and an efficiency of star formation varying with the galactic radius. We conclude that the most important physical processes in creating disk gradients are the inside-out formation and the radial gas flows. More data on abundance gradients both locally and at high redshift are necessary to confirm this conclusion.Comment: Accepted by A&

Identification of presynaptic neurotoxin complexes in the venoms of three Australian copperheads (Austrelaps spp.) and the efficacy of tiger snake antivenom to prevent or reverse neurotoxicity

The venom of the Australian lowlands copperhead, Austrelaps superbus, produces significant and potentially lethal neurotoxic paralysis in cases of clinical envenomation. However, little is known about the neurotoxic components within this venom or venoms from the related alpine copperhead (Austrelaps ramsayi) or pygmy copperhead (Austrelaps labialis). Using the isolated chick biventer cervicis nerve-muscle preparation, all Austrelaps venoms were found to exhibit potent and rapid inhibition of nerve-evoked twitch contractions and block of contractures to nicotinic agonists, consistent with postsynaptic neurotoxic activity. Following separation by size-exclusion liquid chromatography under non-denaturing conditions, all Austrelaps venoms were found to also contain a high molecular mass fraction with only weak phospholipase A 2 (PLA 2) activity that caused a slow inhibition of twitch contractions, without inhibiting contractures to nicotinic agonists. These actions are consistent with the presence of additional snake presynaptic PLA 2 neurotoxin (SPAN) complexes in all three Austrelaps venoms. However, there was no evidence of direct muscle damage produced by any Austrelaps venom or SPAN complex. Monovalent tiger snake antivenom was effective in neutralising the neurotoxicity of both whole venom and the SPAN complex. However antivenom was unable to effectively reverse whole venom neurotoxicity, or prejunctional SPAN neurotoxicity, once established. Given the strong neurotoxicity of all Austrelaps venoms, particularly A. ramsayi and A. labialis, effective bites from these copperhead species should be considered potentially lethal. Furthermore, clinicians need to be aware of possible irreversible presynaptic neurotoxicity following envenomation from all copperhead species and that early antivenom intervention is important in preventing further development of toxicity. © 2011 Elsevier Ltd

The black beat of Lisbon: Sociabilities, music and resistances

Since the 1970s, Portugal has established itself as one of the largest migratory flows of Africans to Europe, especially from its former colonies to the Portuguese capital. Gradually, there are numerous precarious and informal construction neighborhoods, with the presence of Angolans, Cape Verdeans, Guineans and Sao Tome, where cultural expressions of the diaspora's musical repertoire are affirmed. From the 2000s, the phenomenon of music digitization contributed to the maintenance of permanent and instantaneous exchanges with what was played and consumed in the countries of origin. New opportunities for crosses and reinterpretations of musical genres have become possible, reinforced by the local senses conferred by young people born and / or raised in Afro-Lisbon producing innovative aesthetic expressions. Started by young blacks, a musical scene with its own circuits of production, circulation and consumption known as "batida" appears in the outskirts of Lisbon, a style influenced by African rhythms, namely Angola's kuduro and electronic music. Djs were the main responsible for affirming this new style, giving this sound a centrality in the market of youth consumption in Portugal and in Europe. Quinta do Mocho is a key neighborhood to understand this dynamics, where from very precarious conditions, some young people took advantage of the opportunities offered by digital devices to create this rhythm, also moving local sociabilities and parties. Home to some of the country's top "batida" Djs, Quinta do Mocho has become an area of intense musical production, where home studios and street parties influence the new global fashions. If some of the DJs in the neighborhood make a music career, most of them do not have the opportunity to make it a full and autonomous profession. In this article, we propose to analyze the trajectories of these young Djs, correlating their life experiences with the transformations that have occurred in the neighborhood and in the musical genre "beat" in recent years. We intend to analyze the relationship between creativity and sociability in music with the resistances built by them in relation to racism, segregation and colonialist forms of social demarcation of existence, space and knowledge.info:eu-repo/semantics/acceptedVersio

Chemical evolution of the bulge of M31: predictions about abundance ratios

We aim at reproducing the chemical evolution of the bulge of M31 by means of a detailed chemical evolution model, including radial gas flows coming from the disk. We study the impact of the initial mass function, the star formation rate and the time scale for bulge formation on the metallicity distribution function of stars. We compute several models of chemical evolution using the metallicity distribution of dwarf stars as an observational constraint for the bulge of M31. Then, by means of the model which best reproduces the metallicity distribution function, we predict the [X/Fe] vs. [Fe/H] relations for several chemical elements (O, Mg, Si, Ca, C, N). Our best model for the bulge of M31 is obtained by means of a robust statistical method and assumes a Salpeter initial mass function, a Schmidt-Kennicutt law for star formation with an exponent k=1.5, an efficiency of star formation of $\sim 15\pm 0.27\, Gyr^{-1}$, and an infall timescale of $\sim 0.10\pm 0.03$Gyr. Our results suggest that the bulge of M31 formed very quickly by means of an intense star formation rate and an initial mass function flatter than in the solar vicinity but similar to that inferred for the Milky Way bulge. The [$\alpha$/Fe] ratios in the stars of the bulge of M31 should be high for most of the [Fe/H] range, as is observed in the Milky Way bulge. These predictions await future data to be proven.Comment: Accepted for publication by MNRA

Between school and university: The study of the historical scientific instruments collection of the Liceo Maffei in Verona

Since 2014 the Museum of the History of Physics of the University of Padua has been working on the study and valorisation of the collection of historical scientific instruments kept at the high school “Scipione Maffei” in Verona, one of the oldest high schools in Italy. The Cabinet of Physics of “Liceo Maffei”, founded in 1802, currently consists of about 550 instruments, acquired until the 1960s. Besides the Museum’s staff, the project has involved two physics teachers and a group of students, who participated in different phases of the work on the collection. This article intends to present the collection, the project, and the results achieved so far. We also aim at highlighting the potentialities and possible future developments of the project, a project which can become a model for other schools

Lack of Temporal Impairment in Patients With Mild Cognitive Impairment

In the present study, we investigate possible temporal impairment in patients with mild cognitive impairment (MCI) and the amount of temporal distortions caused by the presentation of emotional facial expressions (anger, shame, and neutral) in MCI patients and controls. Twelve older adults with MCI and 14 healthy older adults were enrolled in the present study. All participants underwent a complete neuropsychological evaluation. We used three timing tasks to tap temporal abilities, namely time bisection (standard intervals lasting 400 and 1600 ms), finger-tapping (free and 1 s), and simple reaction-time tasks. The stimuli used in the time bisection task were facial emotional stimuli expressing anger or shame to investigate a possible contribution of emotional information as previously observed in healthy adults. MCI patients showed temporal abilities comparable to controls. We observed an effect of facial emotional stimuli on time perception when data were analyzed in terms of proportion of long responses, and this result was mainly driven by the temporal overestimation when a facial expression of anger was presented in controls. Results seem to suggest that the severity of the cognitive dysfunction accounts more for subjective temporal impairment than a compromised internal clock

Poredbene hematološke i biokemijske analize divovske amazonske kornjače uzgajane pod lošim i normalnim hranidbenim uvjetima

Besides indicating the baseline values of the species, blood parameter assessments of chelonian may also be used as quick tools for diagnosing health status. An investigation was carried out to assess and compare red blood cells parameters, white blood cell (WBC) and total thrombocyte counts and certain blood biochemical parameters for freshwater turtles, Podocnemis expansa Schweigger, 1812 (Pelomedusidae) reared on normal (control group) and poor nutrition (malnourished group). For the malnourished turtles, a signififi cant decrease (P<0.05) in red blood cell counts was found, including hematocrit, plasma glucose, plasma total protein, cholesterol and urea levels, as well as WBC counts, azurophils and heterophils. Malnutrition did not alter the hemostasis, but caused severe normocytic-hypocromic anemia and marked immune depression, which were diagnosed here. This study was the fifi rst to characterize the physiological and immune status of giant turtles from the Amazon under adverse nutritional conditions.Osim za utvrđivanje osnovnih vrijednosti osebujnih za vrstu, pretraživanje krvnih pokazatelja može u kornjača biti rabljeno za brzo određivanje njihova zdravstvenoga stanja. Istraživanje je poduzeto da se odrede i usporede pokazatelji crvenih krvnih stanica, bijelih krvnih stanica, ukupnog broja trombocita i neki biokemijski pokazatelji za slatkovodne kornjače Podocnemis expansa Schweigger, 1812 (Pelomedusidae) uzgajane u normalnim (kontrolna skupina) i lošim hranidbenim uvjetima (pokusna skupina). U kornjača uzgajanih u lošim uvjetima ustanovljen je značajno smanjen (P<0,05) broj crvenih krvnih stanica kao i smanjene vrijednosti hematokrita, razine glukoze u plazmi, razine ukupnih proteina plazme, kolesterola i mokraćevine te broj bijelih krvnih stanica, azurofila i heterofila. Loša hranidba nije utjecala na hemostazu, ali je prouzročila tešku normocitnu hipokromnu anemiju i znatnu imunodepresiju. Ovo je prvo istraživanje u kojem je prikazan fiziološki i imunološki status divovske kornjače iz Amazone, držane u nepovoljnim hranidbenim uvjetima