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The existence of a full asymptotic expansion for the heat content asymptotics of an operator of Laplace type with classical Zaremba boundary conditions on a smooth manifold is established. The first three coefficients in this asymptotic expansion are determined in terms of geometric invariants; partial information is obtained about the fourth coefficient., Comment: 24 pages

We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from stellar companions, their X-ray properties are consistent with magnetic Cataclysmic Variables, or High Mass X-ray Binaries (HMXB) at low accretion-rates. A direct way to decide between these possibilities and hence between alternative formation scenarios is to measure or constrain the luminosity distribution of the companions. Using infrared (J, H, K, Br-gamma) imaging, we searched for counterparts corresponding to typical HMXB secondaries: spectral type B0V with K<15 at the GCR. We found no significant excess of bright stars in Chandra error circles, indicating that HMXBs are not the dominant X-ray source population, and account for fewer than 10% of the hardest X-ray sources., Comment: 4 pages, 3 figures, 1 table, accepted in ApJ Letters for publication

We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed to measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s) accreting white dwarfs, neutron stars and stellar mass black holes in the Galactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra) and optical (NOAO 4m-Mosaic imaging), and a followup spectroscopy and IR identification program. The survey has now extended through the first 6 years of Chandra data using serendipitous sources detected in 105 distinct ACIS-I and -S fields observed in 154 pointings and covered by 65 deep Mosaic images in V, R, I, and H-alpha. ChaMPlane incorporates fields with galactic latitude |b| <~ 12 deg and selected to be devoid of bright point or diffuse sources, with exposure time > ~20 ksec, and (where possible) minimum NH. We describe the scientific goals and introduce the X-ray and optical/IR processing and databases. We derive preliminary constraints on the space density or luminosity function of cataclysmic variables from the X-ray/optical data for 14 fields in the Galactic Anticenter. The lack of ChaMPlane CVs in these Anticenter fields suggests their space density is ~ 3x below the value (3 x 10^-5 pc^-3) found for the solar neighborhood by previous X-ray surveys. Companion papers describe the X-ray and optical processing in detail, optical spectroscopy of ChaMPlane sources in selected Anticenter fields and IR imaging results for the Galactic Center field. An Appendix introduces the ChaMPlane Virtual Observatory (VO) for online access to the X-ray and optical images and source catalogs for ready display and further analysis., Comment: 10 pages, 7 figures, 2 tables, accepted in ApJ for publication

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Intercalibratie is het afstemmen van biologische waterkwaliteitsbeoordelingen tussen lidstaten. Het is een verplichting die voortkomt uit de Kaderrichtlijn Water. De Europese Unie wil dat beoordelingen tussen lidstaten onderling vergelijkbaar zijn. Ze kan dan controleren of deze beoordelingen conform de richtlijn zijn. Dit artikel gaat in op de achtergronden van intercalibratie en laat een tussenstand zien van het procesverloop en de resultaten tot nu toe

RIVM rapport:In Farming with a Future (FwF) farmers, together with extension officers and researchers, work towards sustainable production systems for arable crops, open air vegetables, flower bulbs and ornamental trees. Systematic measurements of water quality on the participating farms are conducted by RIVM; for the first time in 2002. The results of these measurements are presented and discussed in this report. Special attention is paid to the concentration of several forms of nitrogen (N) and phosphorous (P), and the relationships with land use and the physical environment. The groundwater of 15 of the 37 farms investigated presented nitrate concentrations (farm averages) below the boundary value of 50 mg/l (as NO3). Groundwater of the farms with arable crops on clay soils and of those with flower bulbs presented the lowest nitrate concentrations as compared to groundwater of the other farm sectors. The highest concentrations were found in groundwater of farms with open air vegetables, followed by the farms with ornamental trees. These differences are partly explained by differences in the physical environment. Farms on 'wet' soils, including all flower bulb farms and arable farms on clay, present lower concentrations than farms on naturally well-drained soils with a deep groundwater table. However, when physical environments appear to be comparable (sandy soils), farms with open air vegetables generally present higher groundwater nitrate concentrations than farms with arable crops. With respect to groundwater P-concentrations, among the participating farms, the ones with flower bulbs clearly present the highest values, (average farm average total-P = 7,4 mg/l), followed by those with arable crops on clay soils (average 0,61 mg/l) and a few farms with arable crops on sandy soils. The most important factors determining the high groundwater P-concentrations on the farms with flower bulbs seem to be the small phosphate retention capacity of the sandy dune soils where flower bul, In Telen met Toekomst (TmT) werken agrarische ondernemers, samen met adviseurs en onderzoekers, aan duurzame bedrijfssystemen voor akkerbouw, vollegrondsgroenteteelt, bloembollen en boomteelt. In 2002 heeft het RIVM voor het eerst systematisch waterkwaliteitsmetingen verricht op de deelnemende bedrijven. De resultaten van deze metingen worden in dit rapport gepresenteerd en besproken. Hierbij wordt vooral gekeken naar de concentraties van verschillende vormen van stikstof en fosfaat en de verbanden met landgebruik en omgevingsfactoren. De bedrijfsgemiddelde nitraatconcentratie in het grondwater (of bodemvocht) was op 15 van de 37 onderzochte bedrijven lager dan de grenswaarde van 50 mg/l (als NO3). Het grondwater bij de akkerbouwers-op-klei en de bollentelers vertoont de laagste nitraatconcentraties in vergelijking met de andere sectoren. De volle-gronds-groente-telers springen er uit met de hoogste waarden, gevolgd door de boom-telers. Deze verschillen kunnen deels verklaard worden door omgevingsspecifieke factoren. Bedrijven op 'natte' gronden, waaronder alle bollentelers en akkerbouwers-op-klei, vertonen lagere concentraties dan bedrijven op van nature goedgedraineerde gronden met een diepe grondwaterstand. Echter, ook onder ogenschijnlijk vergelijk-bare omstandigheden vertoont het grondwater van de bedrijven in de vollegronds-groenteteelt in het algemeen hogere nitraatconcentraties dan bij de akkerbouwers op zand. Voor wat betreft P in het grondwater, springen de bollentelers er duidelijk uit met de hoogste concentraties (gemiddeld totaal-P = 7,4 mg/l), gevolgd door de akkerbouwers-op-klei (gemiddeld 0,61 mg/l) en enkele akkerbouwers-op-zand. De belangrijkste factoren die verantwoordelijk lijken te zijn voor de hoge fosfaatconcentraties in het grondwater van de bollentelers zijn het geringe fosfaatvastleggend vermogen van de betreffende duingronden; de hoge fosfaatoverschotten (met name in het verleden); de hoge grondwaterstand en de diepe grondbewerking. Het be

In de biologische veehouderij wordt getracht dierziekten zoveel mogelijk te voorkomen door de selectie van dieren met een hoge natuurlijke weerstand, het geven van gezonde voeding en het zorgdragen voor een optimaal leefklimaat waardoor hetnatuurlijke gedrag van de dieren zoveel mogelijk tot uiting kan komen. Indien een dier toch ziek wordt gaat de voorkeur uit naar een behandeling met een alternatieve geneeswijze zoals homeopathie, mits aangetoond is dat deze middelen ook effectief zijnvoor de betreffende aandoening. Van veel van deze alternatieven is de werkzaamheid echter nog niet bewezen. De doelstelling van dit onderzoek was het door middel van een enquête inventariseren van het gebruik van reguliere diergeneesmiddelen enalternatieve middelen in de biologische pluimveehouderij in Nederland. Uit het onderzoek blijkt dat de registratie van dierziekten en preventieve en curatieve behandelingsmethoden op de 33 leghen en 5 vleeskuikenbedrijven voor verbetering vatbaaris.

Item does not contain fulltext, OBJECTIVES: To investigate whether clinical practice guidelines in different countries take ethnic differences between patients into consideration and to assess the scientific foundation of such ethnic specific recommendations. DESIGN: Analysis of the primary care sections of clinical practice guidelines. SETTING: Primary care practice guidelines for type 2 diabetes mellitus, hypertension, and asthma developed in the USA, Canada, the UK, and the Netherlands. MAIN OUTCOME MEASURES: Enumeration of the ethnic specific information and recommendations in the guidelines, and the scientific basis and strength of this evidence. RESULTS: Different guidelines do address ethnic differences between patients, but to a varying extent. The USA guidelines contained the most ethnic specific statements and the Dutch guidelines the least. Most ethnic specific statements were backed by scientific evidence, usually arising from descriptive studies or narrative reviews. CONCLUSION: The attention given to ethnic differences between patients in clinical guidelines varies between countries. Guideline developers should be aware of the potential problems of ignoring differences in ethnicity.

We report the discovery of two spectroscopic binaries in the field of the old open cluster M67 -- S1063 and S1113 -- whose positions in the color-magnitude diagram place them approximately 1 mag below the subgiant branch. A ROSAT study of M67 independently discovered these stars to be X-ray sources. Both have proper-motion membership probabilities greater than 97%; precise center-of-mass velocities are consistent with the cluster mean radial velocity. S1063 is also projected within one core radius of the cluster center. S1063 is a single-lined binary with a period of 18.396 days and an orbital eccentricity of 0.206. S1113 is a double-lined system with a circular orbit having a period of 2.823094 days. The primary stars of both binaries are subgiants. The secondary of S1113 is likely a 0.9 Mo main-sequence star, which implies a 1.3 Mo primary star. We have been unable to explain securely the low apparent luminosities of the primary stars; neither binary contain stars presently limited in radius by their Roche lobes. We speculate that S1063 and S1113 may be the products of close stellar encounters involving binaries in the cluster environment, and may define alternative stellar evolutionary tracks associated with mass-transfer episodes, mergers, and/or dynamical stellar exchanges.

We use differential CCD photometry to search for variability in BVI among 990 stars projected in and around the old open cluster M 67. In a previous paper we reported results for 22 cluster members that are optical counterparts to X-ray sources; this study focuses on the other stars in our observations. A variety of sampling rates were employed, allowing variability on time scales ranging from \sim 0.3 hours to \sim 20 days to be studied. Among the brightest sources studied, detection of variability as small as sigma approx 10 mmag is achieved (with > 3 sigma confidence); for the typical star observed, sensitivity to variability at levels sigma approx 20 mmag is achieved. The study is unbiased for stars with 12.5 < B < 18.5, 12.5 < V < 18.5, and 12 < I < 18 within a radius of about 10 arcmin from the cluster centre. In addition, stars with 10 < BVI < 12.5 were monitored in a few small regions in the cluster. We present photometry for all 990 sources studied, and report the variability characteristics of those stars found to be variable at a statistically significant level. Among the variables, we highlight several sources that merit future study, including stars located on the cluster binary sequence, stars on the giant branch, blue stragglers, and a newly discovered W UMa system., Comment: 12 pages, including 6 figures and 5 tables. Tables 1 and 3 only available in electronic version of paper. Accepted by A&A

Waterplanten vervullen in ondiepe meren zoals het IJsselmeergebied een belangrijke rol in het voedselweb. Het voorkomen van waterplanten in het IJsselmeergebied en kansrijke maatregelen om waterplanten verder te stimuleren worden besproken

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VU Amsterdam, 19 januari 1996, Promotores : Rauwerda, J.A., Boers, G.H.J., Jacobs, C., Item does not contain fulltext

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