THE APM CLUSTER SURVEY: CLUSTER DETECTION AND LARGE-SCALE STRUCTURE

The APM Cluster Survey was based on a modification of Abell's original classification scheme for galaxy clusters. Here we discuss the results of an investigation of the stability of the statistical properties of the cluster catalogue to changes in the selection parameters. For a poor choice of selection parameters we find clear indications of line-of-sight clusters, but there is a wide range of input parameters for which the statistical properties of the catalogue are stable. We conclude that clusters selected in this way are indeed useful as tracers of large-scale structure.Comment: to appear in Proceedings of the XXXth Moriond Conference. 4 pages, gzipped, uuencoded postscript (inc. 2 figures

Congressional Risk Proposals

Dr. Paxman relates how an ambitious environmental agenda supported by the Administration and many members of the 103d Congress was ultimately derailed. He associates this with an apparently ever-growing interest in risk assessment

On the CCD Calibration of Zwicky galaxy magnitudes & The Properties of Nearby Field Galaxies

We present CCD photometry for galaxies around 204 bright (m_Z < 15.5) Zwicky galaxies in the equatorial extension of the APM Galaxy Survey, sampling and area over 400 square degrees, which extends 6 hours in right ascension. We fit a best linear relation between the Zwicky magnitude system, m_Z, and the CCD photometry, B, by doing a likehood analysis that corrects for Malmquist bias. This fit yields a mean scale error in Zwicky of 0.38 mag per magnitude: ie Delta m_Z = (0.62 \pm 0.05) Delta B and a mean zero point of = -0.35 \pm 0.15 mag. The scatter around this fit is about 0.4 mag. Correcting the Zwicky magnitude system with the best fit model results in a 60% lower normalization and 0.35 mag brighter M_* in the luminosity function. This brings the CfA2 luminosity function closer to the other low redshift estimations (eg Stromlo-APM or LCRS). We find a significant positive angular correlation of magnitudes and position in the sky at scales smaller than about 5 armin, which corresponds to a mean separation of 120 Kpc/h. We also present colours, sizes and ellipticities for galaxies in our fields which provides a good local reference for the studies of galaxy evolution.Comment: Full size figures can be found in http://www.ieec.fcr.es/cosmo-www/zwicky.ps Version accepted for publication in MNRAS. Extended discussion on properties of nearby galaxies. References added. An inconsistency in the R band isophote used has been corrected. Main results and conclusions are unchange

THE CALIFORNIA ROCKFISH CONSERVATION AREA AND GROUNDFISH TRAWLERS AT MOSS LANDING HARBOR

This article uses a bioeconomic model and data for groundfish trawlers at Moss Landing Harbor in Central California to analyze effects of spatial closures that were implemented recently by West Coast fishery managers to reduce bycatch of overfished groundfish stocks. The model has a dynamic linear rational expectations structure, and estimates of its parameters exhibit spatial variation in microeconomic and ecological factors that affect decisions about where and when to fish. Test results show that variation in marginal costs of crowding externalities and biological rates of stock productivity are the most significant factors to consider in the spatial management of roundfish trawlers at Moss Landing.Resource /Energy Economics and Policy,

The Apm Galaxy Survey IV: Redshifts of Rich Clusters of Galaxies

We present redshifts for a sample of 229 clusters selected from the APM Galaxy Survey, 189 of which are new redshift determinations. Non-cluster galaxy redshifts have been rejected from this sample using a likelihood ratio test based on the projected and apparent magnitude distributions of the cluster fields. We test this technique using cluster fields in which redshifts have been measured for more than 10 galaxies. Our redshift sample is nearly complete and has been used in previous papers to study the three dimensional distribution of rich clusters of galaxies. 157 of the clusters in our sample are listed in the Abell catalogue or supplement, and the remainder are new cluster identifications.Comment: 15 pages UUencoded compressed postscript. Submitted to Monthly Notices of the R.A.

Brownian ratchet in a thermal bath driven by Coulomb friction

The rectification of unbiased fluctuations, also known as the ratchet effect, is normally obtained under statistical non-equilibrium conditions. Here we propose a new ratchet mechanism where a thermal bath solicits the random rotation of an asymmetric wheel, which is also subject to Coulomb friction due to solid-on-solid contacts. Numerical simulations and analytical calculations demonstrate a net drift induced by friction. If the thermal bath is replaced by a granular gas, the well known granular ratchet effect also intervenes, becoming dominant at high collision rates. For our chosen wheel shape the granular effect acts in the opposite direction with respect to the friction-induced torque, resulting in the inversion of the ratchet direction as the collision rate increases. We have realized a new granular ratchet experiment where both these ratchet effects are observed, as well as the predicted inversion at their crossover. Our discovery paves the way to the realization of micro and sub-micrometer Brownian motors in an equilibrium fluid, based purely upon nano-friction.Comment: main paper: 4 pages and 4 figures; supplemental material joined at the end of the paper; a movie of the experiment can be viewed http://www.youtube.com/watch?v=aHrdY4BC71k ; all the material has been submitted for publication [new version with substantial changes in the order of the presentation of the results; differences with previous works have been put in evidence

Laboratory Animal Science AD 2000

The writer attempts to predict events likely to affect the future practice of Laboratory Animal Science. It is expected the number of experimental animals used will decline over the next decades for several reasons. These include a greater emphasis in research at the cellular, rather than the whole body, level and the redirection of much of the present animal based research of human diseases to man himself as the main experimental subject. This last prediction is based onan assessment of developments in technology and socio-economic factors whereby knowledge and control of human diseases will be obtained by epidemiological and non-invasive studies of human populations.The longterrn effects of the economic recession which have affected considerably animal based and other research in most countries, are also considered, as too is the impact of new legislation in some and, overall, the changing attitude of scientists, technicians and the general public on the experimental use of animals.The consequences of the decline in the number of experimental animals used, the availability of better experimental animals commercially, the recognition of the need for better experimental models and design upon the management of animal houses and the employment of animal technicians is then assessed.It is concluded that economic and scientific factors will lead to new concepts of animal house design and function. Of critical importance, it is considered, is recognition that the animal technician of the future should be selected, trained and qualified to fulfil an exacting scientific role if Laboratory Animal Science is to be effectively, economically and humanely practised

Using Electrophysiology to Investigate Changes in Brain Activation in Individuals with Chronic Stroke

Many individuals who have experienced a stroke also experience persistent decrements in several domains, such as sensorimotor, language, and cognition. While rehabilitation for these deficits is helpful even decades after a stroke, there is limited information available to determine the most effective pairing of treatment with individual deficits. Further, despite decades of neuroimaging research, our understanding of optimal recovery patterns following stroke is relatively poor. In order to improve outcomes for individuals living with chronic deficits due to stroke, neurophysiological biomarkers corresponding to recovery patterns and treatment response are needed. Electroencephalography (EEG) holds great potential for identifying biomarkers as it directly measures brain activation, and is non-invasive, reliable, replicable, and portable. Further, almost all individuals post-stroke are able to tolerate EEG recording. In addition, different methods of analyzing EEG data allow multiple information streams to be gleaned from a single dataset. In this study, 27 persons with chronic stroke (PWCS) and 27 neurologically healthy controls completed speech, language, cognitive, and sensorimotor behavioral assessments. Participants also completed two EEG sessions approximately one month apart which included recording of brain activity at rest and during language, cognitive, and motor tasks. Spectral EEG and event-related potential (ERP) analyses revealed significant differences between neurologically healthy controls and PWCS both at rest and during an auditory oddball task. Test-retest reliability measured across a one-month interval varied by group, task, and electrode montages or regions of interest from poor to excellent. The spectral EEG analysis showed changes previously reported during the acute and sub-acute phase of recovery persist into the chronic phase. ERP analysis demonstrated that individuals with a wide range of post-stroke deficits perform significantly differently during a cognitive task. However, no statistically significant differences were observed between healthy controls and this mixed group during language tasks. Finally, reliability findings indicate some tasks and measures may be appropriate for use in determining treatment response. These results provide support for the use of EEG as a biomarker in the chronic phase in a general stroke population. Future research should investigate the utility of EEG in specific subgroups of persons with chronic stroke

Examining General versus Condition-Specific Health Related Quality of Life across Weight Categories in an Adolescent Sample

Approximately 34% of adolescents are overweight or obese which can be accompanied by physical, psychosocial, and economic consequences. Increasingly, pediatric overweight/obesity research has focused on Health Related Quality of Life (HRQoL) as a health outcome. This study examined differences in HRQoL across weight categories in adolescents, specifically, the sensitivity of using a general versus condition-specific measure. Further, the influence of gender was explored. Data were extracted from Wave 2 of Team Up for Healthy Living, a school-based obesity prevention program targeting adolescents in Southern Appalachia. Participants (N = 918; 50% Female; 93% Caucasian; 90% 9th graders) completed the Pediatric Quality of Life (PedsQL) Inventory (general) and PedsQL Multidimensional Fatigue Scale (condition-specific) measures as part of a larger survey. Body mass index-for-age and -sex percentiles were calculated using actual height and weight, and students were classified as underweight, healthy weight, overweight, or obese according to Centers for Disease Control and Prevention (CDC) criteria. Two 4 (weight category: underweight vs. healthy weight vs. overweight vs. obese) x 2 (gender: male vs. female) factorial analyses of variance (ANOVAs) were calculated to compare mean scores of total HRQoL (both generic and condition-specific). Additionally, 7 factorial multivariate analyses of variance (MANOVAs) were conducted with each measure’s subdomains. Fisher’s Least Significant Difference post hoc analyses were run to assess differences between groups, at a significance level of p\u3c0.05. The current study revealed no interaction effect between total HRQoL (assessed via the generic or condition-specific measure) and weight category and gender; however, main effects were found for both weight category (assessed via a generic measure only) and gender (assessed via both generic and condition-specific measures). Additional research is needed to examine the impact of utilizing different measures and the potential role of gender as well as other factors that may influence HRQoL across weight categories. These issues are important as researchers to date utilize a variety of HRQoL measures making interpretation of findings difficult and often do not consider other variables such as gender that may influence findings

Future Navies—Present Issues

The U.S. Navy is transforming itself to deal with a wider range of missions than the traditional blue-water, major combat operations that it has tradi- tionally been equipped to handle.1 That emerging transformation has resulted in a number of new programs, technologies, and strategies that raise interesting, and sometimes complex, legal issues. Lawyers advising the Navy’s leadership through this transformational process are analyzing these legal issues now, in the present, to ensure that the future U.S. Navy is properly, and legally, orga- nized, trained, and equipped