Transformation of a star into a planet in a millisecond pulsar binary

Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.     

Myelin basic protein: location of multiple independent antigenic regions

Immnunization of guinea pigs with homologous myelin basic protein induces antibodies that differ in their ability to bind specific peptide fragments of the protein. Antiserums with differing specificities made it possible to demonstrate at least three mutually exclusive antigenic sites in the protein molecule. One of these sites is located between residues 44 and 89, another between 90 and 116, and the third between 117 and 170.     

N-beta-Alanyldopamine: Major Role in Insect Cuticle Tanning

N-beta-Alanyldopamine is the major tyrosine metabolite in the hemolymph and cuticle during pupal tanning in the tobacco hornworm, Manduca sexta L. Its concentration in hemolymph increases over 800-fold above larval levels by the start of tanning and decreases as the pupal cuticle darkens and hardens. It is a major catechol in species representing several insect orders and is the preferred substrate for pupal cuticular o-diphenol oxidase. In insects, N-beta-alanyldopamine appears to be the main precursor for tanning chemicals at certain developmental stages.     

Identification of an allatotropin from adult manduca sexta

A peptide that strongly stimulates the secretion of juvenile hormone from corpora allata in vitro (allatotropin) has been purified from extracts of heads of pharate adult Manduca sexta. The primary structure of this 13-residue peptide has been determined: H-Gly-Phe-Lys-Asn-Val-Glu-Met-Met-Thr-Ala-Arg-Gly-Phe-NH(2). This neurohormone has no sequence similarity with any known neuropeptide from other organisms. Synthetic allatotropin, as well as truncation fragments, including one with the five amino terminal residues deleted, showed in vitro activity indistinguishable from that of native allatotropin.     

Stabilisierung der Erträge virusinfizierter Kartoffelherkünfte durch das antiphytovirale Präparat 2,4-Dioxohexahydrotriazin

Zusammenfassung In mehrj?hrigen Parzellenversuchen wurde durch Behandlung mit 2,4-Dioxohexahydrotriazin (DHT), einer neu entwickelten antiphytoviralen Substanz im Durchschnitt von 57 st?rker virusinfizierten Herkünften (durchschnittlicher Virusbesatz 24.6%) der Ertrag hochsignifikant um 1.1 t/ha (=6.5%) erh?ht. Bei 49 gesunden Herkünften (durchschnittlicher Virusbesatz 4.8%) wurden demgegenüber die Ertr?ge nicht ver?ndert. Demnach darf die angeführte Ertragserh?hung der antiviralen Wirkung des DHT zugeschrieben werden. In 44 Grossfl?chenversuchen in Konsumkartoffelbest?nden (Virusbesatz etwa zwischen 10 und 30%), wurde der Ertrag hochsignifikant um 1.4 t/ha (=8.0%) erh?ht. Werden die im trocken-heissen Jahr 1976 in ausgesprochenen Dürregebieten erhaltenen Ergebnisse eliminiert, ergeben sich in den Parzellenversuchen mit virusinfizierten Herkünften hochsignifikante Mehrertr?ge von 1.9 t/ha (=9.7%) und bei den Grossfl?chenversuchen von 2.3 t/ha (=12.6%).

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Summary Studies have been made to determine whether the use of 2.4-dioxohexahydrotriazine (DHT), a newly developed antiphytoviral compound with satisfactory virostatic activity and a favourable chemotherapeutic index (Schuster et al., 1979a, b) can reduce or prevent viral depression of the yield of ware potatoes. Between 1973 and 1977 a total of 106 plot tests were made, using a block design with four replicates. In addition, between 1975 and 1977, 44 large-scale field trials were carried out, the area treated in most of these being 20 ha. In every case, yields from plants treated with DHT five times at intervals of fourteen days were compared with those from untreated control plants. Seed stocks used for the plot tests were classified on the basis of eye excision tests as ‘healthy’ (virus infection less than 10%, average 4.8%) or ‘virus-infected’ (infection greater than 10%, average 24.6%). In the case of 57 ‘virus-infected’ stocks, DHT treatment resulted in a highly significant increase in yield—on average 1.1 t/ha=6.5% (Table 1). On the other hand, treatment with DHT had no material effect on the yield from 49 ‘healthy’ stocks. This indicates that the increase in yield resulted from the antiviral activity of DHT. In the 44 large-scale field trials, carried out in ware crops in which the level of virus infection was generally between 10% and 30%, a highly significant increase in yield was obtained — on average 1.4 t/ha=8%. Included in the data, however, are minor increases in yield recorded in the trials carried out in 1976 (an unusually hot, dry year) in areas badly affected by drought. If these are ignored, a highly significant average increase in yield of 1.9 t/ha=9.7% is obtained when the results of the plot and field trials are combined (Table 1). It is evident from these results that a considerable increase in yield may be obtained through the use of DHT to stabilize yields from virus infected seed stocks. This antiviral preparation has the added advantage of being non-toxic and very economical in use.

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Résumé Des études ont été effectuées afin de conna?tre dans quelle mesure la 2,4-dioxohexahydrotriazine (DHT), substance antiphytovirale nouvellement développée, permet de réduire ou d'éviter les chutes de rendement dans les cultures de pommes de terre de consommation. Ce produit ralentit considérablement, et de manière durable la reproduction du PVX ainsi que celle d'autres virus (Schuster et al., 1979a, b). Au cours des années 1973 à 1977, 106 parcelles disposées en blocs avec 4 répétitions ont été testées. D'autre part, de 1975 à 1977, 44 essais en grande culture couvrant une surface de 20 ha ont été effectués. Dans tous les cas, les surfaces traitées 5 fois à la DHT, à des intervalles de 14 jours, ont été comparées avec des parcelles non traitées. Lors de la récolte des parcelles, il a été prélevé un tubercule par plante pour un postcontr?le virologique. Suivant les résultats du test, les plants ont été classés selon leur taux de contamination par les virus. Pour les lots présentant un taux de contamination de moins de 10% au départ, le taux de contamination moyen fut de 4.8%. Les lots contaminés à plus de 10% présentèrent une attaque moyenne de 24%. Dans les lots contaminés par le virus, la DHT cut pour effet une augmentation hautement significative du rendement, soit 1,1 t/ha (=6,5%, tableau 1). En revanche, par le traitement de 49 parcelles saines, les rendements n'ont pas été influencés par la DHT. Par conséquent, l'augmentation du rendement mentionnée peut être attribuée à l'action anti-virale de la DHT. Sur 44 essais de pommes de terre de consommation en grande culture où la proportion de plantes contaminées atteignait 10–30%, une augmentation hautement significative de rendement a été obtenue, 1,4 t/ha (8.0%). Ces chiffres comprennent également les résultats des essais 1976, année chaude et séche dans certaines régions. En excluant les résultats de 1976, on obtient par les traitements sur les essais parcellaires, une augmentation de récolte hautement significative, soit 1,9 t/ha (=9.0%), et 11,3% pour les traitements en grande culture (tableau 1). Ces résultats démontrent que par le traitement avec la préparation anti-virale DHT, une augmentation non négligeable de rendement peut être obtenue sur des cultures contaminées par le virus, les frais étant économiquement acceptables.

     

Analysis of sampling strategies to substantiate freedom from disease in large areas

In this paper, we deal with the strategies of surveys to substantiate freedom from disease for a certain territory. Infection might not be distributed homogeneously. So, a relatively high within-herd prevalence might be observed while the herd-level prevalence is lower. For this situation, we compare various two-stage sample strategies.

The calculation of appropriate sample sizes becomes quite complicated. The theoretical generalization of the hypergeometric distribution by Cameron and Baldock [Prev. Vet. Med. 24 (1998) 1] introduces a simple way to evaluate multi-stage sample sizes while regarding real-test properties. We demonstrate the theoretical foundations of these calculations. These principles open up the possibility of optimizing costs or other relevant variables, by choosing the appropriate sample strategy (each of which ensures the same -level for the first stage). In addition, we evaluate the statistical power of the complete strategies under consideration.

Furthermore, we apply our theoretical results to a data example of Brucella melitensis. We used the herd-size situation in Germany, characterized by many small sheep holdings and only a few large ones. The consequences of real-test properties on sample sizes and on the applicability of several strategies are discussed.     

Evaluating the effects of upstream lakes and wetlands on lake phosphorus concentrations using a spatially-explicit model

Lake phosphorus concentrations are strongly influenced by the surrounding landscape that generates phosphorus loads and water inflow to lakes, and the physical characteristics of the lake that determine the fate of these inputs. In addition, the presence, connectivity, and configuration of upstream lakes and wetlands likely affect downstream lake phosphorus concentrations. These freshwater landscape features have only sometimes been incorporated into phosphorus loading models, perhaps because of the need for spatially-explicit approaches that account for their location and hydrologic configuration. In this paper, we developed a lake phosphorus concentration model that includes three modules to estimate phosphorus loading, water inflow, and phosphorus retention, respectively. In modeling phosphorus loading and water inflow, we used a spatially-explicit approach to address their export at sources and their attenuation along flow-paths. We used 161 headwater lakes for model calibration and 28 headwater lakes for model validation. Using the calibrated model, we examined the effects of upstream lakes and wetlands on downstream lake phosphorus concentrations. To examine the effects of upstream lakes, we compared the output of the calibrated model for three additional datasets (208 lakes in total) that contained increasing area of upstream lakes. To examine the effect of upstream wetlands, we used the calibrated model to compare flow-path cell series that contained wetlands and those that did not. In addition, we simulated catchments in which all wetlands were converted to forest and recalculated downstream lake phosphorus concentrations. We found that upstream lakes decreased the phosphorus concentrations in downstream lakes; and, counter-intuitively, we found that wetlands increased phosphorus concentrations in most downstream lakes. The latter result was due to the fact that although wetlands reduced phosphorus loads to downstream lakes, they also reduced water inflow to downstream lakes and thus increased the phosphorus concentration of inflows to lakes. Our results suggest that when modeling lake phosphorus concentrations, freshwater features of the landscape and their spatial arrangement should be taken into account.     

Effects of flooding on the recruitment, damage and mortality of riparian tree species: A field and simulation study on the Rhine floodplain

The extensive flooding by the river Rhine on May 12 1999 provided an opportunity to investigate the impact of such an extreme event in terms of damage and mortality of adult trees in floodplains. Such data is highly valuable for determining the potential impact of climate change on the zonation of tree species along rivers. We analysed an extensive dataset of the damage and mortality suffered by groups of adult trees of the following species as a consequence of this flood: the hardwoods Acer campestre L., Acer platanoides L., Acer pseudoplatanus L., Alnus glutinosa (L.) Gaertn., Carpinus betulus L., Fagus sylvatica L., Fraxinus excelsior L., Juglans nigra L., Prunus avium (L.) L., Quercus robur L., Tilia cordata Mill., Ulmus laevis Pall. and Ulmus minor Miller, and the softwoods Salix spp. L. and Populus spp. L.A logistic survivorship curve revealed that mortality of A. platanoides, A. pseudoplatanus and T. cordata increased significantly with increasing duration of flooding; C. betulus and F. excelsior showed a significant increase of damage and mortality with increasing flooding depth. There was no mortality of Salix spp. and Populus spp. in either the flooded or unflooded areas. No statistically significant relationships were found for the other tree species. Multivariate analysis revealed that flooding duration, flooding depth and flooding velocity explain 19%, 11% and 8%, respectively, of the variation in damage and mortality of trees.The survivorship curves of adult trees obtained in this study were combined with similar curves of saplings based on an earlier study and applied in an individual-tree, process-based simulation model. The simulated effects of flooding on an initial random distribution of trees species on a hypothetical floodplain resulted in a realistic zonation of tree species along the river. When extreme events were simulated, the zonation shifted upward. This demonstrates the model's usefulness in assessment and planning studies of the impacts of climate change on tree species composition in river floodplains in north-west Europe.