Galaxy bulges and their black holes: a requirement for the quenching of star formation

One of the central features of the last 8 to 10 billion years of cosmic history has been the emergence of a well-populated red sequence of non-star-forming galaxies. A number of models of galaxy formation and evolution have been devised to attempt to explain this behavior. Most current models require feedback from supermassive black holes (AGN feedback) to quench star formation in galaxies in the centers of their dark matter halos (central galaxies). Such models make the strong prediction that all quenched central galaxies must have a large supermassive black hole (and, by association, a prominent bulge component). I show using data from the Sloan Digital Sky Survey that the observations are consistent with this prediction. Over 99.5% of red sequence galaxies with stellar masses in excess of 10^{10} M_{\sun} have a prominent bulge component (as defined by having a Sersic index n above 1.5). Those very rare red sequence central galaxies with little or no bulge (n<1.5) usually have detectable star formation or AGN activity; the fraction of truly quenched bulgeless central galaxies is <0.1% of the total red sequence population. I conclude that a bulge, and by implication a supermassive black hole, is an absolute requirement for full quenching of star formation in central galaxies. This is in agreement with the most basic prediction of the AGN feedback paradigm.Comment: 6 pages, 4 color figures (figure 1 is of slightly degraded quality). To appear in August 1 edition of the Astrophysical Journa

Evidence for a Positive Cosmological Constant from Flows of Galaxies and Distant Supernovae

Recent observations of high-redshift supernovae seem to suggest that the global geometry of the Universe may be affected by a `cosmological constant', which acts to accelerate the expansion rate with time. But these data by themselves still permit an open universe of low mass density and no cosmological constant. Here we derive an independent constraint on the lower bound to the mass density, based on deviations of galaxy velocities from a smooth universal expansion. This constraint rules out a low-density open universe with a vanishing cosmological constant, and together the two favour a nearly flat universe in which the contributions from mass density and the cosmological constant are comparable. This type of universe, however, seems to require a degree of fine tuning of the initial conditions that is in apparent conflict with `common wisdom'.Comment: 8 pages, 1 figure. Slightly revised version. Letter to Natur

Non-linear Stochastic Galaxy Biasing in Cosmological Simulations

We study the biasing relation between dark-matter halos or galaxies and the underlying mass distribution, using cosmological $N$-body simulations in which galaxies are modelled via semi-analytic recipes. The nonlinear, stochastic biasing is quantified in terms of the mean biasing function and the scatter about it as a function of time, scale and object properties. The biasing of galaxies and halos shows a general similarity and a characteristic shape, with no galaxies in deep voids and a steep slope in moderately underdense regions. At \sim 8\hmpc, the nonlinearity is typically \lsim 10 percent and the stochasticity is a few tens of percent, corresponding to $\sim 30$ percent variations in the cosmological parameter $\beta=\Omega^{0.6}/b$. Biasing depends weakly on halo mass, galaxy luminosity, and scale. The time evolution is rapid, with the mean biasing larger by a factor of a few at $z\sim 3$ compared to $z=0$, and with a minimum for the nonlinearity and stochasticity at an intermediate redshift. Biasing today is a weak function of the cosmological model, reflecting the weak dependence on the power-spectrum shape, but the time evolution is more cosmology-dependent, relecting the effect of the growth rate. We provide predictions for the relative biasing of galaxies of different type and color, to be compared with upcoming large redshift surveys. Analytic models in which the number of objects is conserved underestimate the evolution of biasing, while models that explicitly account for merging provide a good description of the biasing of halos and its evolution, suggesting that merging is a crucial element in the evolution of biasing.Comment: 27 pages, 21 figures, submitted to MNRA

Bimodal AGNs in Bimodal Galaxies

By their star content, the galaxies split out into a red and a blue population; their color index peaked around u-r=2.5 or u-r=1, respectively, quantifies the ratio of the blue stars newly formed from cold galactic gas, to the redder ones left over by past generations. On the other hand, upon accreting substantial gas amounts the central massive black holes energize active galactic nuclei (AGNs); here we investigate whether these show a similar, and possibly related, bimodal partition as for current accretion activity relative to the past. To this aim we use an updated semianalytic model; based on Monte Carlo simulations, this follows with a large statistics the galaxy assemblage, the star generations and the black hole accretions in the cosmological framework over the redshift span from z=10 to z=0. We test our simulations for yielding in close detail the observed split of galaxies into a red, early and a blue, late population. We find that the black hole accretion activities likewise give rise to two source populations: early, bright quasars and later, dimmer AGNs. We predict for their Eddington parameter $\lambda_E$ -- the ratio of the current to the past black hole accretions -- a bimodal distribution; the two branches sit now under $\lambda_E \approx 0.01$ (mainly contributed by low-luminosity AGNs) and around $\lambda_E \approx 0.3-1$. These not only mark out the two populations of AGNs, but also will turn out to correlate strongly with the red or blue color of their host galaxies.Comment: 7 pages, accepted for publication in the Astrophysical Journa

Dynamics of Macroscopic Tunneling in Elongated BEC

We investigate macroscopic tunneling from an elongated quasi 1-d trap, forming a 'cigar shaped' BEC. Using recently developed formalism we get the leading analytical approximation for the right hand side of the potential wall, i.e. outside the trap, and a formalism based on Wigner functions, for the left side of the potential wall, i.e. inside the BEC. We then present accomplished results of numerical calculations, which show a 'blip' in the particle density traveling with an asymptotic shock velocity, as resulted from previous works on a dot-like trap, but with significant differences from the latter. Inside the BEC a pattern of a traveling dispersive shock wave is revealed. In the attractive case, we find trains of bright solitons frozen near the boundary.Comment: 6 pages, 15 figure

Venture community: democratisation of entrepreneurship in developing economies

The motivation of this paper is to assist SMEs (mainly micro and informal enterprises) in developing economies to find the required resources to establish, or develop, their business. We introduce the concept of 'Venture Communities' to provide direct peer-to-peer connections between individuals and SMEs in all parts of the global market. We draw on the well-established concepts of networking, crowdfunding, living labs and value co-creation. The contribution we make lies in the introduction of a novel ecosystem, constructed by multiple actors, through dynamic and interconnected networks, accumulating resources for the benefit of all stakeholders of this community. Our model presents a challenge to the conventional conceptualizations of dyadic relationships between developed economies and emerging economies. Alternatively, we suggest anti-essentialist communities that are temporary constellation of social elements from all parts of the global market to create "hybridized and nomadic" (Laclau and Mouffe 1995) market arrangements

Pain control in the continuity of care.

As cancer is earlier diagnosed and its treatments improve, palliative care is increasingly playing a vital role in the oncology population. The concept and the timing of application of palliative care have evolved in the last decades. The WHO pain ladder and the greater understanding of appropriate multimodal pain control treatments have dramatically improved the management of cancer pain. Integration of palliative care, which appears crucial for a proper management of patients, can be defined as the provision of palliative care both during curative cancer treatment and after curative treatment has ceased. Clinical assistance should be delivered by specialized physicians in different fields, psychologists and nurses, and should include all aspects of advanced cancer care, from diagnosis to the treatment of symptoms. A further aspect of integration of palliative care concerns the role of the continuity of care in acute or emergency contexts both for out- and inpatients. Further improvements in the management of cancer pain are needed. First, the WHO ladder should be modified with further steps, like those of interventional pain control procedures and techniques, with the aim of being effective also for the small proportion of nonresponsive patients. Second, more research is needed to find out which interventions aiming to improve continuity of care of cancer patients are beneficial to improve patient, provider and process of care outcomes and to identify which outcomes are the most sensitive to change. Of crucial importance would be the development of a standardised instrument to measure the continuity of care in cancer patients. This article is a brief overview on the management of cancer pain, from the pharmacological treatments reported by WHO ladder, to the need for integration and continuity of care