The Cosmological Mean Density and its Local Variations Probed by Peculiar Velocities

Peculiar velocities thoughout the region of the local supercluster are reconstructed by two different orbit-retracing methods. The requirement of the optimal correlation between the radial components of reconstructed velocities and the observed peculiar velocities derived from our extensive new catalog of distances puts stringent constraints on the values of the cosmological parameters. Our constraints intersect those from studies of microwave background fluctuations and statistical properties of galaxy clustering: the ensemble of constraints are consistent with Omega_m=0.22\pm 0.02. While motions throughout the Local Supercluster provide a measure of the mean ratio of mass to light, there can be large local fluctuations. Our reconstruction of the infall velocities in the immediate vicinity of the Virgo Cluster shows that there is a mass-to-light anomaly of a factor of 3 to 6 between groups in the general field environment and the heavily populated Virgo Cluster.Comment: 4 pages, 2 figures, version to appear in Astrophysical Journal Letter

The observed infall of galaxies towards the Virgo cluster

We examine the velocity field of galaxies around the Virgo cluster induced by its overdensity. A sample of 1792 galaxies with distances from the Tip of the Red Giant Branch, the Cepheid luminosity, the SNIa luminosity, the surface brightness fluctuation method, and the Tully-Fisher relation has been used to study the velocity-distance relation in the Virgocentric coordinates. Attention was paid to some observational biases affected the Hubble flow around Virgo. We estimate the radius of the zero-velocity surface for the Virgo cluster to be within (5.0 - 7.5) Mpc corresponding to (17 - 26)^\circ at the mean cluster distance of 17.0 Mpc. In the case of spherical symmetry with cosmological parameter \Omega_m=0.24 and the age of the Universe T_0= 13.7 Gyr, it yields the total mass of the Virgo cluster to be within M_T=(2.7 - 8.9) * 10^{14} M_\sun in reasonable agreement with the existing virial mass estimates for the cluster.Comment: 22 pages, 11 figures, 2 tables. Accepted for publication in MNRA

Towards a Truly Interdisciplinary Approach to Product Design Education

The education of new designers and innovators who can develop new product and service interventions to meet society’s challenges in the 21st century is a complex task. Design itself lies at the intersection of technology, art and science [1]. Technological University Dublin (DIT)’s BSc (Hons) Product Design programme was developed to reflect this reality and was uniquely designed to operate across three distinct Colleges (Engineering, Creative Arts and Business) within DIT. Its key objective is to give students a firm grounding in these three areas and to produce graduates capable of understanding and executing all stages of the design process with a distinct focus on producing products and interventions which are technically feasible, consumer appropriate and commercially credible. While still a relatively new programme, it has continued to innovate in both structure [2] [3] and pedagogy [4] [5] [6] to ensure a clear focus on the needs of society and of industry. Students of the programme have repeatedly won awards in a wide variety of design areas including creative, technical and business innovation, while graduates have gone on to successful careers in a number of fields and industry sectors. The authors believe that the model employed in this programme could be fruitfully applied to the development of cross-disciplinary programmes in a variety of settings within the education of product designers and engineers

Our Peculiar Motion Away from the Local Void

The peculiar velocity of the Local Group of galaxies manifested in the Cosmic Microwave Background dipole is found to decompose into three dominant components. The three components are clearly separated because they arise on distinct spatial scales and are fortuitously almost orthogonal in their influences. The nearest, which is distinguished by a velocity discontinuity at ~7 Mpc, arises from the evacuation of the Local Void. We lie in the Local Sheet that bounds the void. Random motions within the Local Sheet are small. Our Galaxy participates in the bulk motion of the Local Sheet away from the Local Void. The component of our motion on an intermediate scale is attributed to the Virgo Cluster and its surroundings, 17 Mpc away. The third and largest component is an attraction on scales larger than 3000 km/s and centered near the direction of the Centaurus Cluster. The amplitudes of the three components are 259, 185, and 455 km/s, respectively, adding collectively to 631 km/s in the reference frame of the Local Sheet. Taking the nearby influences into account causes the residual attributed to large scales to align with observed concentrations of distant galaxies and reduces somewhat the amplitude of motion attributed to their pull. On small scales, in addition to the motion of our Local Sheet away from the Local Void, the nearest adjacent filament, the Leo Spur, is seen to be moving in a direction that will lead to convergence with our filament. Finally, a good distance to an isolated galaxy within the Local Void reveals that this dwarf system has a motion of at least 230 km/s away from the void center. Given the velocities expected from gravitational instability theory in the standard cosmological paradigm, the distance to the center of the Local Void must be at least 23 Mpc from our position. The Local Void is large!Comment: Tentatively scheduled for Astrophysical Journal, 676 (March 20), 2008. 18 figures, 3 tables including web link for 2 tables, web links to 2 video

Nonlocal Gravity: Modified Poisson's Equation

The recent nonlocal generalization of Einstein's theory of gravitation reduces in the Newtonian regime to a nonlocal and nonlinear modification of Poisson's equation of Newtonian gravity. The nonlocally modified Poisson equation implies that nonlocality can simulate dark matter. Observational data regarding dark matter provide limited information about the functional form of the reciprocal kernel, from which the original nonlocal kernel of the theory must be determined. We study this inverse problem of nonlocal gravity in the linear domain, where the applicability of the Fourier transform method is critically examined and the conditions for the existence of the nonlocal kernel are discussed. This approach is illustrated via simple explicit examples for which the kernels are numerically evaluated. We then turn to a general discussion of the modified Poisson equation and present a formal solution of this equation via a successive approximation scheme. The treatment is specialized to the gravitational potential of a point mass, where in the linear regime we recover the Tohline-Kuhn approach to modified gravity.Comment: 27 pages, 4 figures; v2: minor improvements, accepted for publication in J. Math. Phy

Atlas: Commercial fisheries for shellfish around Ireland

Fishing is the longest standing and most prevalent marine activity in the territorial and coastal waters of Ireland. Today over 2,000 vessels are registered as commercial fishing vessels and over 80% of these are under 12m in length and depend largely or completely on the territorial waters of the state. The increased level and diversity of activity in the maritime space has highlighted the need for efficient and co-ordinated management of its use to avoid conflict and to identify, where possible, synergies both within and between sectors. These objectives are reflected in the Marine Spatial Planning (MSP) Directive which came into force in 2014 and which requires EU Member States to establish and implement maritime spatial planning (EU/89/2014). There is a need to manage and plan industrial activity, including fishing, in a spatial context. These spatial data have already been used in Ireland to assess the interaction between fisheries and Special Areas of Conservation (SACs) (www.fishingnet.ie/fishinginnaturaareas, Marine Institute 2015). The new data are presented here but the scope is restricted to Shellfish fisheries and with an emphasis on the distribution of these fisheries in internal and territorial waters

UCDs in the Coma Cluster

As part of the HST/ACS Coma Cluster Treasury Survey, we have undertaken a Keck/LRIS spectroscopic campaign to determine membership for faint dwarf galaxies. In the process, we discovered a population of Ultra Compact Dwarf galaxies (UCDs) in the core region of the Coma cluster. At the distance of Coma, UCDs are expected to have angular sizes 0.01 < R_e < 0.2 arcsec. With ACS imaging, we can resolve all but the smallest ones with careful fitting. Candidate UCDs were chosen based on magnitude, color, and degree of resolution. We spectroscopically confirm 27 objects as bona fide UCD members of the Coma cluster, a 60% success rate for objects targeted with M_R < -12. We attribute the high success rate in part to the high resolution of HST data and to an apparent large population of UCDs in Coma. We find that the UCDs tend to be strongly clustered around giant galaxies, at least in the core region of the cluster, and have a distribution and colors that are similar to globular clusters. These findings suggest that UCDs are not independent galaxies, but rather have a star cluster origin. This current study provides the dense environment datapoint necessary for understanding the UCD population.Comment: 6 pages, 9 figures, to appear in the conference proceedings of "A Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010

On the kinematics of the Local cosmic void

We collected the existing data on the distances and radial velocities of galaxies around the Local Void in the Aquila/Hercules to examine the peculiar velocity field induced by its underdensity. A sample of 1056 galaxies with distances measured from the Tip of the Red Giant Branch, the Cepheid luminosity, the SNIa luminosity, the surface brightness fluctuation method, and the Tully-Fisher relation has been used for this purpose. The amplitude of outflow is found to be ~300 km/s. The galaxies located within the void produce the mean intra-void number density about 1/5 of the mean external number density of galaxies. The void's population has a lower luminosity and a later morphological type with the medians: M_B = -15.7^m and T = 8 (Sdm), respectively.Comment: Version 1. 14 pages, 8 figures, 2 tables. Accepted to Astrophysics, Volume 54, Issue

Do Differences In Educational Culture Affect The Process And Outcome Of Undergraduate Design Practice?

Designers undertake projects in different ways, and as might be expected, these have the potential to produce a wide variety of outputs. While the designed artefact is understandably often the focus when evaluating student designers, the importance of process is paramount in design education. This is underpinned by the fact that a novice designer may produce a single successful project without a full understanding of how that artefact came about. However, a designer who can reflect upon and understand the process, is better equipped to repeat or further evolve this process in future projects. It is well understood that organisational structure and culture influences the ways designers choose to approach a project, from initial brief formation, through ideation and development, to the detail design and execution phases. An aspect not thoroughly understood is how different methods in design education specifically influence the methodologies designers employ in approaching a project, and therefore that projects outcome. Previous work has examined the influence of cultural background on the formation of a design brief, but not on the entire process. This research attempts to understand that influence, by forming links between the educational background as an input and process and artefact as outputs. This paper proposes a research framework in which both artefact and process are examined. To this end, cultural probe type tools, which actively encourage design students to reflect upon and report upon their process during a design project, are used to allow student design practitioners to self-report their design process

Sedentary behaviours and cognitive function among community dwelling adults aged 50+ years:Results from the Irish longitudinal study of ageing

Background: Sedentary behaviours (SB) are risk factors for poor cardiovascular health and all-cause mortality. However, their role in cognitive health in older adults is unclear. A few studies have examined associations between sedentary behaviours and cognition, but are limited by heterogeneity and insufficient longitudinal analyses. Therefore more robust studies, which would address identified limitations, are needed to accurately determine associations. Method: This study analysed data collected from participants aged 50+ years of The Irish Longitudinal Study of Ageing (TILDA). We conducted cross-sectional linear regression with multivariate imputation analyses of baseline data from wave 1 (N = 8163, weekday-sitting time), and wave 3 (N = 6400, weekday-television viewing); longitudinal analyses between waves 1\u20133 (sitting) and waves 3\u20134 (television). Sedentary behaviours were analysed as both categorical and continuous variables. Outcome of cross-sectional analyses was standardised regression co-efficient of associations between sedentary exposures and cognitive function in respective waves, while for longitudinal analyses was cognitive change (verbal memory, verbal fluency, and global cognition) between waves based on standardised residuals. Result: Study found significant but mild cross-sectional associations between 1-h increase in weekday-television viewing and poorer verbal memory (b = 120.02, CI: 120.04, 120.003, P &lt; 0.05) and verbal fluency (b = 120.02, CI: 120.04, 120.002, P &lt; 0.05). Baseline television viewing of 3.5+ h/day had mild but significant association with a decline in verbal fluency 2 years later in participants aged 65+ years, when compared with a reference category of &lt;1.5 h of TV viewing (b = 120.12, CI: 120.23, 120.001, P &lt; 0.05). Conclusion: Our study findings indicated some association between increased levels of weekday-television viewing time, independent of physical activity, and poor cognition cross-sectionally and longitudinally in middle-aged and older adults. Intervention studies are needed to confirm the effects of SB on cognition in older adults. Public health campaigns should be targeted at displacing high levels of television viewing, in excess of 3.5 h/day among older adults. \ua9 2020 Elsevier Lt