Life events and acute cardiovascular reactions to mental stress: a cohort study

Objective: This study addressed the issue of whether frequent exposure to life events is associated with aggravation or blunting of cardiovascular reactions to acute mental stress. Methods: In a substantial cohort of 585 healthy young adults, systolic and diastolic blood pressure and pulse rate were recorded at rest and in response to a mental arithmetic stress task. Participants indicated, from a list of 50 events, those they had experienced in the last year. Results: There was an overall association between life events and blunted cardiovascular reactivity that was driven by variations in the frequency of exposure to desirable events. The total number of events and the number of personal events were negatively associated with systolic blood pressure and pulse rate reactions to acute stress, whereas the number of work-related events was negatively associated with diastolic blood pressure and pulse rate reactivity. The negative association between total events and systolic blood pressure reactivity was stronger for women than men, whereas men exposed to frequent undesirable events showed enhanced diastolic blood pressure reactivity. The blunting of pulse rate reactivity associated with frequent personal life events was evident particularly for those who had a relatively large number of close friends. Conclusions: The nature and extent of the association between life events exposure and stress reactivity in young adults depends on the valence of the events together with the sex of the individual and their social network size

Globular Cluster Systems and the Missing Satellite Problem: Implications for Cold Dark Matter Models

We analyze the metallicity distributions of globular clusters belonging to 28 early-type galaxies in the survey of Kundu & Whitmore (2001). A Monte Carlo algorithm which simulates the chemical evolution of galaxies that grow hierarchically via dissipationless mergers is used to determine the most probable protogalactic mass function for each galaxy. Contrary to the claims of Kundu & Whitmore, we find that the observed metallicity distributions are in close agreement with the predictions of such hierarchical formation models. The mass spectrum of protogalactic fragments for the galaxies in our sample has a power-law behavior, with an exponent of roughly -2. This spectrum is indistinguishable from the mass spectrum of dark matter halos predicted by cold dark matter models for structure formation. We argue that these protogalactic fragments, the likely sites of globular cluster formation in the early universe, are the disrupted remains of the "missing" satellite galaxies predicted by cold dark matter models. Our findings suggest that the solution to the missing satellite problem is through the suppression of gas accretion in low-mass halos after reionization, or via self-interacting dark matter, and argue against models with suppressed small-scale power or warm dark matter.Comment: 28 pages, 19 postscript figures. Accepted for publication in the Astrophysical Journa

Intergalactic Globular Clusters

We confirm and extend our previous detection of a population of intergalactic globular clusters in Abell 1185, and report the first discovery of an intergalactic globular cluster in the nearby Virgo cluster of galaxies. The numbers, colors and luminosities of these objects can place constraints on their origin, which in turn may yield new insights to the evolution of galaxies in dense environments.Comment: 2 pages, no figures. Talk presented at JD6, IAU General Assembly XXV, Sydney, Australia, July 2003, to appear in Highlights of Astronomy, Vol. 1

Top team trust, knowledge sharing and innovation

In the present research, we developed a causal model of organizational innovation incorporating the literature on top management teams (TMT) and knowledge-sharing in organizations. We hypothesized that top team composition and trust would predict organizational innovation through the mediating variables of task reflexivity and knowledge-sharing. We tested the model using data collected from thirty-five knowledge intensive firms in Ireland operating in the software industry. Results indicated that top team trust, knowledge-sharing and task reflexivity have both direct and indirect relationships with organizational innovation. Implications for research and practice are discussed

An Overview of Uncovered and Suspected Large-Scale Structures behind the Milky Way

Various dynamically important extragalactic large-scale structures in the local Universe lie behind the Milky Way. Most of these structures (predicted and unexpected) have only recently been made ``visible'' through dedicated deep surveys at various wavelengths. The wide range of observational searches (optical, near infrared, far infrared, radio and X-ray) for galaxies in the Zone of Avoidance (ZOA) will be reviewed and the uncovered and suspected large-scale structures summarised. Particular emphasis is given to the Great Attractor region where the existence of yet another cluster is suspected (Woudt 1998). Predictions from reconstructions of the density field in the ZOA are discussed and compared with observational evidence. Although no major structures are predicted out to about v < 10000 km/s for which no observational evidence exists, the comparison between reconstructed density fields and the observed galaxy distribution remain important as they allow derivations of the density and biasing parameters.Comment: To appear in PASA 16. Proceedings of workshop "HI in the Local Universe, II", held in Melbourne, Sept. 1998. 9 pages, LaTeX2e, 1 encapsulated PS figur

Scanning electrochemical cell microscopy : a versatile method for highly localised corrosion related measurements on metal surfaces

The development of tools that can probe corrosion related phenomena at the (sub)microscale is recognized to be increasingly important in order to understand the surface structural factors (grain orientation, inclusions etc.) that control the (electro)chemical stability (corrosion susceptibility, pitting, passivity etc.) of metal surfaces. Herein we consider the application of scanning electrochemical cell microscopy (SECCM), a relatively new member of the electrochemical droplet cell (EDC) family, for corrosion research and demonstrate the power of this technique for resolving structure and activity at the (sub)microscale. Hundreds of spatially-resolved (2 μm droplet size) potentiodynamic polarization experiments have been carried out on the several hours timescale and correlated to complementary structural information from electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) in order to determine the effect of grain orientation and inclusions on electrochemical processes at low carbon steel in neutral solution (10 mM KNO3). Through this approach, it has been shown unequivocally that for the low index planes, anodic currents in the passive region (an indicator of corrosion susceptibility) are greatest on (101) planes compared to (100) and (111) planes. Furthermore, individual sub-micron MnS inclusions have been probed and shown to undergo active dissolution followed by rapid repassivation. This study demonstrates the high versatility of SECCM and the considerable potential of this technique for addressing structure-activity problems in corrosion and electromaterials science

Intelligent center pivot

Irrigation systems are designed to apply a relatively uniform amount of water to fields that often time needs to be varied due to factors such as soil types, multiple crops, and topography. With the potential of a field to vary, a significant amount of water, energy, nutrients and minerals can be wasted, which can ultimately reduce crop yields. As a solution, we are now developing an intelligent irrigation system that automatically adjusts application rates to match the requirements of individual management zones within a particular field. A tabletop version of a center pivot is being constructed to promote adoption and to demonstrate this innovative technology. This model has working pumps to replicate individual irrigation zones to vary the application rate by automatically turning sections off or on, and by changing the rotational speed of the center pivot. The tabletop center pivot will be used during field days, trade shows, and meeting with producers to demonstrate the uses, benefits, and effectiveness of this irrigation technology

Spatial subsidies drive sweet spots of tropical marine biomass production

Spatial subsidies increase local productivity and boost consumer abundance beyond the limits imposed by local resources. In marine ecosystems, deeper water and open ocean subsidies promote animal aggregations and enhance biomass that is critical for human harvesting. However, the scale of this phenomenon in tropical marine systems remains unknown. Here, we integrate a detailed assessment of biomass production in 3 key locations, spanning a major biodiversity and abundance gradient, with an ocean-scale dataset of fish counts to predict the extent and magnitude of plankton subsidies to fishes on coral reefs. We show that planktivorous fish-mediated spatial subsidies are widespread across the Indian and Pacific oceans and drive local spikes in biomass production that can lead to extreme productivity, up to 30 kg ha−1 day−1. Plankton subsidies form the basis of productivity “sweet spots” where planktivores provide more than 50% of the total fish production, more than all other trophic groups combined. These sweet spots operate at regional, site, and smaller local scales. By harvesting oceanic productivity, planktivores bypass spatial constraints imposed by local primary productivity, creating “oases” of tropical fish biomass that are accessible to humans

Life-history constraints, short adult life span and reproductive strategies in coral reef gobies of the genus Trimma

Body size influences many life-history traits, with small-bodied animals tending to have short life spans, high mortality and greater reproductive effort early in life. In this study, the authors investigated the life-history traits and reproductive strategies of three small-bodied coral reef gobies of the genus Trimma: Trimma benjamini, Trimma capostriatum and Trimma yanoi. The authors found all Trimma species studied attained a small body size of <25 mm, had a short life span of <140 days and experienced high estimated daily mortality of 3.0%–6.7%. Furthermore, the pelagic larval phase accounted for 25.3%–28.5% of the maximum life span, and maturation occurred between 74.1 and 82.1 days at 15.2–15.8 mm, leaving only 35%–43% of the total life span as a reproductively viable adult. All mature individuals had gonad structures consistent with bidirectional sex change, with bisexual gonads including both ovarian and testicular portions separated by a thin wall of connective tissue. In the female and male phases, only ovaries or testes were mature, whereas gonadal tissue of the non-active sex remained. One T. benjamini individual and one T. yanoi individual had ovarian and testicular tissue active simultaneously. The results of this study highlight the life-history challenges small CRFs face on their path to reproduction and reproductive strategies that could be beneficial in fishes with high and unpredictable mortality and short reproductive life spans