Globular Cluster Scale Sizes in Giant Galaxies: Orbital Anisotropy and Tidally Under-filling Clusters in M87, NGC 1399, and NGC 5128

We investigate the shallow increase in globular cluster half-light radii with projected galactocentric distance $R_{gc}$ observed in the giant galaxies M87, NGC 1399, and NGC 5128. To model the trend in each galaxy, we explore the effects of orbital anisotropy and tidally under-filling clusters. While a strong degeneracy exists between the two parameters, we use kinematic studies to help constrain the distance $R_\beta$ beyond which cluster orbits become anisotropic, as well as the distance $R_{f\alpha}$ beyond which clusters are tidally under-filling. For M87 we find $R_\beta > 27$ kpc and $20 < R_{f\alpha} 13$ kpc and $10 < R_{f\alpha} < 30$ kpc. The connection of $R_{f\alpha}$ with each galaxy's mass profile indicates the relationship between size and $R_{gc}$ may be imposed at formation, with only inner clusters being tidally affected. The best fitted models suggest the dynamical histories of brightest cluster galaxies yield similar present-day distributions of cluster properties. For NGC 5128, the central giant in a small galaxy group, we find $R_\beta > 5$ kpc and $R_{f\alpha} > 30$ kpc. While we cannot rule out a dependence on $R_{gc}$, NGC 5128 is well fitted by a tidally filling cluster population with an isotropic distribution of orbits, suggesting it may have formed via an initial fast accretion phase. Perturbations from the surrounding environment may also affect a galaxy's orbital anisotropy profile, as outer clusters in M87 and NGC 1399 have primarily radial orbits while outer NGC 5128 clusters remain isotropic.Comment: 16 pages, 7 figures, 4 tables, Accepted for publication in MNRA

A Green's function approach to Topological Insulator junctions with magnetic and superconducting regions

This work presents a Green's function approach, originally implemented in graphene with well-defined edges, to the surface of a strong 3D Topological Insulator (TI) with a sequence of proximitized superconducting (S) and ferromagnetic (F) surfaces. This consists of the derivation of the Green's functions for each region by the asymptotic solutions method, and their coupling by a tight-binding Hamiltonian with the Dyson equation to obtain the full Green's functions of the system. These functions allow the direct calculation of the momentum-resolved spectral density of states, the identification of subgap interface states, and the derivation of the differential conductance for a wide variety of configurations of the junctions. We illustrate the application of this method for some simple systems with two and three regions, finding the characteristic chiral state of the Quantum Anomalous Hall Effect (QAHE) at the NF interfaces, and chiral Majorana modes at the NS interfaces. Finally, we discuss some geometrical effects present in three-region junctions such as weak Fabry-P\'erot resonances and Andreev bound states.Comment: 14 pages, 6 figure

Effects of oil palm and human presence on activity patterns of terrestrial mammals in the Colombian Llanos

The ability of animals to adjust their behaviour can influence how they respond to environmental changes and human presence. We quantified activity patterns of terrestrial mammals in oil palm plantations and native riparian forest in Colombia to determine if species exhibited behavioural changes depending on the type of habitat and the presence of humans. Despite the large sampling effort (12,403 camera-days), we were only able to examine the activity patterns of ten species in riparian forests and seven species in oil palm plantations, with four species (capybara, giant anteater, lesser anteater and common opossum) being represented by enough records (i.e. n > 20) in both oil palm and forest to allow robust comparisons. Only capybaras showed an apparent change in activity patterns between oil palm plantations and riparian forests, shifting from being crepuscular in forest to predominantly nocturnal inside oil palm plantations. Further, capybaras, giant anteaters and white-tailed deer appeared to modify their activities to avoid human presence inside oil palm plantations by increasing nocturnality (temporal overlap Δ ^ ranged from 0.13 to 0.36), whereas jaguarundi had high overlap with human activities [Δ ^ =0.85 (0.61–0.90)]. Species pair-wise analysis within oil palm revealed evidence for temporal segregation between species occupying the same trophic position (e.g. foxes and jaguarundi), whereas some predators and their prey (e.g. ocelots and armadillos) had high overlaps in temporal activity patterns as might be expected. Our findings shed light on the potential behavioural adaptation of mammals to anthropogenic landscapes, a feature not captured in traditional studies that focus on measures such as species richness or abundance

Structural Parameters of the M87 Globular Clusters

We derive structural parameters for ~2000 globular clusters in the giant Virgo elliptical M87 using extremely deep Hubble Space Telescope images in F606W (V) and F814W (I) taken with the ACS/WFC. The cluster scale sizes (half-light radii r_h) and ellipticities are determined from PSF-convolved King-model profile fitting. We find that the r_h distribution closely resembles the inner Milky Way clusters, peaking at r_h~2.5 pc and with virtually no clusters more compact than r_h ~ 1 pc. The metal-poor clusters have on average an r_h 24% larger than the metal-rich ones. The cluster scale size shows a gradual and noticeable increase with galactocentric distance. Clusters are very slightly larger in the bluer waveband V a possible hint that we may be beginning to see the effects of mass segregation within the clusters. We also derived a color magnitude diagram for the M87 globular cluster system which show a striking bimodal distribution.Comment: ApJ accepte

Recovery and management of actual acid sulphate soils in boyacá (colombia)

Acid sulphate soils (ASS), having very res­tricted use due to their extreme acidity, have been iden­tified within the upper Chicamocha river basin, Boyacá (Colombia). This situation has led to increasing degra­dation of the land, rendering around 3,000 ha of land unproductive. Production alternatives are thus being sought for recovering these flat upland areas, currently suffering from ASS, as they do have agricultural poten­tial. Soils were initially characterised and identified in a problem area so that possible management of such ASS could then be inferred from the initial study. Increasing doses of calcium hydroxide (Ca(OH)2) (5 to 100 t· ha-1) were then evaluated and determined for neutralising extreme acid conditions in laboratory incubation assays (5-100 t· ha-1). Greenhouse and field tests (random block experimental design with 10 treatments and 4 repeats) were used for observing the response of Avena sativa as an indicator plant; just hen-dung (5-10 t· ha-1) and hen-dung mixed with lime (dry and wet matter) were also evaluated as amendment material. The experiments re­vealed the soils’ chemical changes and reactions following these treatments: pH, Al, ECEC, % AL, % Ca, total S, Mn, Fe and P (i.e. after statistical correlations had been made). These studies led to the soils being recognised as non-coast actual ASS and classifying them as Typic Sulfaquept. The findings indicated that Ca(OH)2 12.5 t· ha-1 mixed with 10 t· ha-1 organic matter (hen-dung) represented the best treatment for obtaining the best A. sativa performance in terms of dry matter production, reflected in positive ASS chemical changes

The close limit from a null point of view: the advanced solution

We present a characteristic algorithm for computing the perturbation of a Schwarzschild spacetime by means of solving the Teukolsky equation. We implement the algorithm as a characteristic evolution code and apply it to compute the advanced solution to a black hole collision in the close approximation. The code successfully tracks the initial burst and quasinormal decay of a black hole perturbation through 10 orders of magnitude and tracks the final power law decay through an additional 6 orders of magnitude. Determination of the advanced solution, in which ingoing radiation is absorbed by the black hole but no outgoing radiation is emitted, is the first stage of a two stage approach to determining the retarded solution, which provides the close approximation waveform with the physically appropriate boundary condition of no ingoing radiation.Comment: Revised version, published in Phys. Rev. D, 34 pages, 13 figures, RevTe

Globular Cluster Systems in Giant Ellipticals: the Mass/Metallicity Relation

Hubble Space Telescope ACS/WFC data in (B,I) are used to investigate the globular cluster populations around 6 gE galaxies ~40 Mpc distant. The total comprises a sample of ~8000 high-probability globular clusters. PSF-convolved King-model profiles are used to measure their individual total magnitudes, colors, and effective radii. The classic bimodal form of the GC color-magnitude distribution shows up unambiguously in all the galaxies, allowing an accurate definition of the mean colors along each of the two sequences as a function of magnitude (the mass/metallicity relation or MMR). The blue, metal-poor cluster sequence shows a clearly defined but nonlinear MMR, changing smoothly from a near-vertical sequence at low luminosity to an increasingly redward slope at higher luminosity, while the red, metal-rich sequence is nearly vertical at all luminosities. All the observed features of the present data agree with the interpretation that the MMR is created primarily by GC self-enrichment, along the lines of the quantitative model of Bailin and Harris (2009): The "threshold" mass at which this effect should become noticeable is near 1 million Solar masses, which is closely consistent with the transition region that is seen in the data. Correlation of the median half-light radii of the GCs with other parameters shows that the metal-poor clusters are consistently 17% larger than those of the metal-rich clusters, at all galactocentric distances and luminosities. At the same time, cluster size scales with halo location as r_h ~ R_gc^0.11, indicating that both metallicity and the external tidal environment play roles in determining the scale size of a given cluster. Lastly, both the red and blue GC components show metallicity gradients with galactocentric distance, following Z ~ R_gc^-0.1.Comment: In press for Astrophysical Journal. Complete preprint with higher quality figures is available at http://physwww.mcmaster.ca/%7Eharris/Publications.htm

Comparación de los perfiles farmacodinámicos de tres moléculas de remifentanilo en cuanto a su respuesta hemodinámica a las maniobras de laringoscopia e intubación traqueal

ResumenIntroducciónEn Colombia se comercializan diferentes moléculas de remifentanilo que nunca han sido comparadas en un entorno clínico.ObjetivoEl objetivo de este estudio fue investigar el perfil farmacodinámico de la molécula innovadora de remifentanilo (grupo O: Glaxo SmithKline Manufacturing S.P.A.) y 2 moléculas genéricas (grupo A: Laboratorios Chalver de Colombia S.A. y grupo B: Instituto Biológico Contemporáneo, Argentina) registradas en Colombia.MétodosSe llevó a cabo un experimento clínico doble ciego, aleatorizado, controlado. Se comparó la molécula original de remifentanilo (grupo O, n=29) frente a las 2 moléculas genéricas (grupo A, n=29; grupo B, n=32) durante la inducción anestésica e intubación orotraqueal de pacientes adultos ASAI sin predictores de vía aérea difícil. Se evaluaron las dosis 6, 8 y 10ng/ml (TCI, Target Controlled Infusion) con el modelo de Minto. La inducción se complementó con propofol 5μg/ml (TCI) con modelo de Schneider y rocuronio 0,6mg/kg. El desenlace primario se evaluó como las diferencias en la presión arterial media y en la frecuencia cardiaca preintubación (momento en que se alcanza la concentración objetivo en sitio efecto) y postintubación (máximo valor alcanzado en 5min).ResultadosSe observó similitud en el perfil farmacodinámico de las moléculas de remifentanilo estudiadas. Las diferencias en el cambio de frecuencia cardiaca fue de 1,27 (IC95%: –3,11;5,67) con la molécula A y 1,40 (IC95%: –2,65;5,46) con la molécula B frente a la molécula O (latidos/min). Las diferencias en el cambio de presión arterial media fueron de 1 (IC95%: –4,81;6,81) para la molécula A y de 1,82 (IC95%: –4,08;7,74) para la molécula B frente a la molécula O (mmHg). Hubo un caso de hipotensión arterial en cada grupo.ConclusiónLos resultados sugieren que desde un punto de vista farmacodinámico las moléculas innovadora y genéricas de remifentanilo son similares para la laringoscopia/intubación con dosis TCI de 6, 8 y 10ng/ml.AbstractIntroductionSeveral remifentanil products are commercialized in Colombia while these have never been compared in a clinical setting.ObjectiveThe aim of this study was to investigate the pharmacodynamic profile of the branded molecule of remifentanil (group O: Glaxo SmithKline Manufacturing S.P.A.) and two unbranded molecules (group A: Laboratorios Chalver de Colombia S.A. and group B: Instituto Biológico Contemporaneo, Argentina) registered in Colombia.MethodsWe carried out a double-blind, randomized, controlled trial. The branded molecule of remifentanil (group O, n=29) was compared with the two unbranded molecules (group A, n=29; group B, n=32) during anesthetic induction and tracheal intubation in adult patients ASAI without predictors for difficult airway. The target controlled infusion (TCI) doses evaluated were 6, 8 and 10ng/ml with the Minto model. Induction was complemented with propofol 5mcg/ml (TCI) with the Schneider model and rocuronium 0.6mg/kg. The primary outcome was defined as the difference in mean arterial pressure and heart rate pre-intubation (TCI equilibrium) and post-intubation (maximum measurement within 5minutes).ResultsA similar pharmacodinamic profile was observed between the studied remifentanil molecules. The differences in the change in heart rate were 1.27 (95% CI: –3.11;5.67) with molecule A and 1.40 (95%CI: –2.65;5.46) with molecule B against molecule O (beats/minute). The differences in the change in mean arterial pressure were 1 (95%CI: –4.81;6.81) for molecule A and 1.82 (95%CI: –4.08;7.74) for molecule B against molecule O (mmHg). There was a case of arterial hypotension in each group.ConclusionThe results suggest that from a pharmacodynamic point of view branded and unbranded remifentanil molecules are similar for laryngoscopy/intubation with TCI doses 6, 8 and 10ng/ml

The Ages, Metallicities and Alpha Element Enhancements of Globular Clusters in the Elliptical NGC 5128: A Homogeneous Spectroscopic Study with Gemini/GMOS

We present new integrated light spectroscopy of globular clusters (GCs) in NGC 5128 in order to measure radial velocities and derive ages, metallicities, and alpha-element abundance ratios. Using Gemini-S 8-m/GMOS, we obtained spectroscopy in the range of ~3400-5700 AA for 72 GCs with S/N > 30 /AA and we have also discovered 35 new GCs within NGC 5128 from our radial velocity measurements. We measured and compared the Lick indices from HdeltaA through Fe5406 with the single stellar population (SSP) models of Thomas et al.(2003,2004). We also measure Lick indices for 41 Milky Way GCs from Puzia et al. (2002) and Schiavon et al. (2005) with the same methodology for direct comparison. Our results show that 68% of the NGC 5128 GCs have old ages (> 8 Gyr), 14% have intermediate ages (5-8 Gyr), and 18% have young ages (< 5 Gyr). However, when we look at the metallicity of the GCs as a function of age, we find 92% of metal-poor GCs and 56% of metal-rich GCs in NGC 5128 have ages > 8 Gyr, indicating that the majority of both metallicity subpopulations of GCs formed early, with a significant population of young and metal-rich GCs forming later. Our metallicity distribution function generated directly from spectroscopic Lick indices is clearly bimodal, as is the color distribution of the same set of GCs. Thus the metallicity bimodality is real and not an artifact of the color to metallicity conversion. The [alpha/Fe] values are supersolar with a mean value of 0.14pm0.04, indicating a fast formation timescale. However, the GCs in NGC 5128 are not as [alpha/Fe] enhanced as the Milky Way GCs also examined in this study. Our results support a rapid, early formation of the GC system in NGC 5128, with subsequent major accretion and/or GC and star forming events in more recent times (abridged).Comment: Accepted to The Astrophysical Journal, 36 pages, 14 figures, 7 table