Time course of target recognition in visual search

Visual search is a ubiquitous task of great importance: it allows us to quickly find the objects that we are looking for. During active search for an object (target), eye movements are made to different parts of the scene. Fixation locations are chosen based on a combination of information about the target and the visual input. At the end of a successful search, the eyes typically fixate on the target. But does this imply that target identification occurs while looking at it? The duration of a typical fixation (~170ms) and neuronal latencies of both the oculomotor system and the visual stream indicate that there might not be enough time to do so. Previous studies have suggested the following solution to this dilemma: the target is identified extrafoveally and this event will trigger a saccade towards the target location. However this has not been experimentally verified. Here we test the hypothesis that subjects recognize the target before they look at it using a search display of oriented colored bars. Using a gaze-contingent real-time technique, we prematurely stopped search shortly after subjects fixated the target. Afterwards, we asked subjects to identify the target location. We find that subjects can identify the target location even when fixating on the target for less than 10ms. Longer fixations on the target do not increase detection performance but increase confidence. In contrast, subjects cannot perform this task if they are not allowed to move their eyes. Thus, information about the target during conjunction search for colored oriented bars can, in some circumstances, be acquired at least one fixation ahead of reaching the target. The final fixation serves to increase confidence rather then performance, illustrating a distinct role of the final fixation for the subjective judgment of confidence rather than accuracy

The chemical composition of a regular halo globular cluster: NGC 5897

We report for the first time on the chemical composition of the halo cluster NGC 5897 (R=12.5 kpc), based on chemical abundance ratios for 27 alpha-, iron-peak, and neutron-capture elements in seven red giants. From our high-resolution, high signal-to-noise spectra obtained with the Magellan/MIKE spectrograph, we find a mean iron abundance from the neutral species of [Fe/H] = -2.04 +/- 0.01 (stat.) +/- 0.15 (sys.), which is more metal-poor than implied by previous photometric and low-resolution spectroscopic studies. NGC 5897 is alpha-enhanced (to 0.34 +/- 0.01 dex) and shows Fe-peak element ratios typical of other (metal-poor) halo globular clusters (GCs) with no overall, significant abundance spreads in iron nor in any other heavy element. Like other GCs, NGC 5897 shows a clear Na-O anti-correlation, where we find a prominent primordial population of stars with enhanced O abundances and ~Solar Na/Fe ratios, while two stars are Na-rich, providing chemical proof of the presence of multiple populations in this cluster. Comparison of the heavy element abundances with the Solar-scaled values and the metal poor GC M15 from the literature confirms that NGC 5897 has experienced only little contribution from s-process nucleosynthesis. One star of the first generation stands out in that it shows very low La and Eu abundances. Overall, NGC 5897 is a well-behaved GC showing archetypical correlations and element-patterns, with little room for surprises in our data. We suggest that its lower metallicity could explain the unusually long periods of RR Lyr that were found in NGC 5897.Comment: 13 pages, 8 figures, accepted for publication in Astronomy & Astrophysic

R-process and alpha-elements in the Galactic disk: Kinematic correlations

Recent studies of elemental abundances in the Galactic halo and in the Galactic disk have underscored the possibility to kinematically separate different Galactic subcomponents. Correlations between the galactocentric rotation velocity and various element ratios were found, providing an important means to link different tracers of star formation and metal enrichment to the Galactic components of different origin (collapse vs. accretion). In the present work we determine stellar kinematics for a sample of 124 disk stars, which we derive from their orbits based on radial velocities and proper motions from the the literature. Our stars form a subsample of the Edvardsson et al. (1993) sample and we concentrate on three main tracers: (i) Europium as an r-process element is predominantly produced in Supernovae of type II. (ii) Likewise, alpha-elements, such as Ca, Si, Mg, are synthesised in SNe II, contrary to iron, which is being produced preferentially in SNe Ia. (iii) The s-process element Barium is a measure of the relative contribution of AGB stars to the Galaxy's enrichment history and has been shown to be an indicator for distinguishing between thin and thick disk stars. All such studies reveal, basically, that stars with low galactocentric rotational velocity tend to have high abundances of alpha-elements and Eu, but lower abundances of, e.g., Ba.Comment: 5 pages, 2 figures, Poster contribution to appear in "Planets To Cosmology: Essential Science In Hubble's Final Years", proceedings of the May 2004 STScI Symposium, M. Livio (ed.), (Cambridge University Press

A statistical analysis of the late-type stellar content in the Andromeda halo

We present a statistical characterization of the carbon-star to M-giant (C/M) ratio in the halo of M31. Based on application of pseudo-filter band passes to our Keck/DEIMOS spectra we measure the 81-77-color index of 1288 stars in the giant stellar stream and in halo fields out to large distances. From this well-established narrow-band system, supplemented by V-I colors, we find only a low number (five in total) of C-star candidates. The resulting low C/M ratio of 10% is consistent with the values in the M31 disk and inner halo from the literature. Although our analysis is challenged by small number statistics and our sample selection, there is an indication that the oxygen-rich M-giants occur in similar number throughout the entire halo. We also find no difference in the C-star population of the halo fields compared to the giant stream. The very low C/M ratio is at odds with the observed low metallicities and the presence of intermediate-age stars at large radii. Our observed absence of a substantial carbon star population in the these regions indicates that the (outer) M31 halo cannot be dominated by the debris of disk-like or SMC-type galaxies, but rather resemble the dwarf elliptical NGC 147.Comment: 11 pages, 10 figures, accepted for publication in the A

Firm Foundations in the Knowledge Intensive Business Service Sector. Results from a Comparative Empirical Study in Three German Regions

A key feature of the knowledge-based economy is a remarkable increase in the number of knowledge intensive business service firms (KIBS). KIBS are based upon highly specialised knowledge and they acquire knowledge in the course of the interaction process that takes place whilst they provide their services. As knowledge and its organisation are tied to personal capabilities and information, spatial “proximity” to providers and users of knowledge appears to be crucial for the foundation and early development of KIBS. The quality of regional environments (e.g. configurations of incubator and intermediate organisations or a regional “entrepreneurial climate”) and the foundation and development of KIBS are obviously interrelated. Based upon a standardised survey, the present paper analyses regional differences in the foundation process and early development of KIBS in three German regions in a comparative way. The results of our descriptive analysis show strong regional ties of founders and KIBS firms during the founding process as a result of spatial proximity. With only slight differences, those ties could be observed in all three regions. They are primarily related to the former activities of the founder, the transfer of results and experiences into the new firm, and spatial proximity to the most important customers or other partners within the exchange of knowledge. Major differences can be derived with regard to the development of the firms (e.g. Munich KIBS firms show a much better development in employment), obstacles in accessing the regional market, and the general assessment of the regional framework conditions from the point-of-view of the KIBS founders.KIBS; firm foundations; interaction; spatial proximity; Germany

A chemical confirmation of the faint Bootes II dwarf Spheroidal Galaxy

We present a chemical abundance study of the brightest confirmed member star of the ultrafaint dwarf galaxy Bootes II from Keck/HIRES high-resolution spectroscopy at moderate signal-to-noise ratios. At [Fe/H] = -2.93 +/- 0.03 (stat.) +/- 0.17 (sys.) this star chemically resembles metal-poor halo field stars and the signatures of other faint dwarf spheroidal galaxies at the same metallicities in that it shows enhanced [alpha/Fe] ratios, Solar Fe-peak element abundances, and low upper limits on the neutron-capture element Ba. Moreover, this star shows no chemical peculiarities in any of the eight elements we were able to measure. This implies that the chemical outliers found in other systems remain outliers pertaining to the unusual enrichment histories of the respective environments, while Bootes II appears to have experienced an enrichment history typical of its very low mass. We also re-calibrated previous measurements of the galaxy's metallicity from the calcium triplet (CaT) and find a much lower value than reported before. The resulting broad metallicity spread, in excess of one dex, the very metal poor mean, and the chemical abundance patterns of the present star imply that Bootes II is a low-mass, old, metal poor dwarf galaxy and not an overdensity associated with the Sagittarius Stream as has been previously suggested based on its sky position and kinematics. The low, mean CaT metallicity of -2.7 dex falls right on the luminosity-metallicity relation delineated over four orders of magnitude from the more luminous to the faintest galaxies. Thus Bootes II's chemical enrichment appears representative of the galaxy's original mass, while tidal stripping and other mass loss mechanisms were probably not significant as for other low-mass satellites.Comment: 10 pages, 5 figures, accepted for publication in the Astrophysical Journa

Determinants of Innovative Activity in Newly Founded Knowledge Intensive Business Service Firms

Innovative activity is performed to a considerable extent in the service sector, namely within the socalled knowledge intensive business services (KIBS). Nevertheless, little is known about the determinants of innovative activity in these firms. In the present paper, some of these determinants are examined on the basis of a recently created dataset of 547 newly founded German firms (KIBS Foundation Survey 2003). The results show that the access to knowledge through cooperation and networking is an important factor determining innovative activity in the KIBS sector, whereas, surprisingly, neither managerial characteristics nor spatial proximity have general influence.

On the significance of economic structure and regional innovation systems for the foundation of knowledge-intensive business services

The shift to new forms of knowledge creation reflects a remarkable increase in the number of knowledge-intensive business service firms (KIBS). KIBS are believed to be one of the main drivers of technological change and economic progress and can be described as users, carriers and sources of innovation (Miles et al. 1995). In addi-tion to macroeconomic implications, newly founded KIBS are considered to play an important role within regional production and innovation systems. As firm founders in early stages of their firms development mostly draw on regional resources and as KIBS acquire knowledge in the course of the interactive process that takes place when the service is provided, an intense interdependency between the regional economic, technological and institutional set-up and newly founded KIBS can be supposed. Within these processes of inter-relationship, proximity between the different actors of the particular innovation and production system clearly matters.However, as entrepreneurship research has hardly ever investigated KIBS and re-search into the role of KIBS in processes of regional change has just begun, this con-tribution analyses the inter-relationships between KIBS foundations and actors within the respective innovation and production system. In a qualitative and conceptual way, in-depth studies of three German metropolitan regions with regard to the foundation of KIBS will be outlined. The results indicate that the necessity to adapt regional structures goes hand in hand with an exploitation of regional knowledge and the crea-tion of bridging institutions in the shape of KIBS foundations. --

New Firms---Different Jobs? An Inquiry into the Quality of Employment in Start-ups and Incumbents

The present contribution addresses the question whether and how qualitative aspects of employment---like weekly hours of work, wages or qualification---differ between new and established firms. Although a wide strand of literature in entrepreneurship research analyses the employment effects of start-ups vs. incumbent firms, our knowledge about differences in these qualitative aspects of employment is rather poor. Labour market research, on the other hand, has been thoroughly accounting for the consequences of technological and organisational change on the characteristics and turnover of jobs, but it rarely has been attempting to consider the relevance of firm entry. Based on the Establishment History Panel, a plant-level dataset constructed from employment information and comprising nearly the entire German economy, we find significant differences between new and incumbent firms with respect to employment quality. Surprisingly, the difference regarding the share of high-qualified labour is---though highly significant---not as high as commonly expected.Start-ups, Employment, Quality of Employment, Germany, Entrepreneurship, Qualification, Wages, Part-Time, Marginal Employment