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298 results on '"Roberts, D. M."'

1. Inductive Power Transfer Through Saltwater

Author

Wandinger, J. N., Roberts, D. M., Bobowski, J. S., and Johnson, T.

Subjects
Physics - Applied Physics
Abstract

We investigated inductive power transfer (IPT) through a rectangular slab of saltwater. Our inductively-coupled transmitters and receivers were made from loop-gap resonators (LGRs) having resonant frequencies near 100 MHz. Electric fields are confined within the narrow gaps of the LGRs making it possible to strongly suppress the power dissipation associated with electric fields in a conductive medium. Therefore, the power transfer efficiency in our system was limited by magnetic field dissipation in the conducting medium. We measured the power transfer efficiency as a function of both the conductivity of the water and the resonant frequency of the LGRs. We also present an equivalent circuit model that can be used to model IPT through a conductive medium. Finally, we show that using dividers to partition the saltwater volume provides another means of enhancing power transfer efficiency., Comment: 5 pages, 5 figures

Published
2021
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2. Alpha E-Taxonomy: Responses from the Systematics Community to the Biodiversity Crisis

Author

Mayo, S. J., Allkin, R., Baker, W., Blagoderov, V., Brake, I., Clark, B., Govaerts, R., Godfray, C., Haigh, A., Hand, R., Harman, K., Jackson, M., Kilian, N., Kirkup, D. W., Kitching, I., Knapp, S., Lewis, G. P., Malcolm, P., von Raab-Straube, E., Roberts, D. M., Scoble, M., Simpson, D. A., Smith, C., Smith, V., Villalba, S., Walley, L., and Wilkin, P.

Published
2008

11. Seasonal and diurnal flight activity patterns in some species of black-flies (Diptera: Simuliidae)

Author

Roberts, D. M.

Subjects
595.77
Abstract

The flight activity of three species of Simuliidae was studied in the Eden Valley, Cumberland. The flies were caught using a net mounted on a vehicle, which was driven at 48 km/h along a circuit, consisting of four roads parallel to the River Eden (at distances of 0.5, 1.5, 5.0 and 6.0 km from the river), and the main road at right angles to the river, between the villages of Langwathby and Melmerby. Equipment in the back of the vehicle allowed the flow of insects from the net to be divided into catches, each of which was caught over a distance of 1 km. An anemometer on the mouth of the net allowed the insects to be calculated as a concentration, so that the catches on the four roads could be directly compared. The female flies were all dissected and thus divided into different physiological groups. The main divisions were into nulliparous and parous flies, each of which was sub-divided into blood-thirsty and blood-fed flies, and into gravid and parasitised flies. The diurnal rhythm of the three simuliid species was studied, noting the differences between the different physiological groups. The effect of the weather on these rhythms was examined. By comparing the four parallel roads, the spatial distribution of the three species was studied. The distribution, and thus powers of dispersal, of the nulliparous and parous flies was compared, and the effect of the presence of parasites on this ability to disperse was noted.

Published
1974

14. Abstracts of papers presented at the Sixth InternationalVerticillium Symposium Abstracts of papers presented at the Seventh Conference of the Entomological Society of Israel: June 19–23,1994 Hod Hotel, Dead Sea, Israel December 12, 1994 ARO, The Volcani Center, Bet Dagan, Israel

Author

Kening, L., Rouse, D. I., German, T. L., Roberts, D. M., Bainbridge, B. W., Evans, H. C., Heale, J. B., Koike, M., Watanabe, M., Nagao, H., Perez-Lara, Catalina, Pérez-Artés, Encarnación, Jiménez-Díaz, Rafael M., Barasubiye, Tharcisse, Richard, Claude, Dostaler, Daniel, Parent, Jean-Guy, Hamelin, Richard C., Laberge, Serge, Harris, D. C., Yang, J. R., Karapapa, V. K., Barbara, D. J., Carder, J. H., Morton, A., Tabrett, A. M., Rowe, Randall C., Botseas, Despina D., Wakatabe, D., Shiraishi, T., Iijima, T., Paplomatas, E. J., Elena, K., Portenko, Ljudmila G., Akimov, G. I., Poshnagova, Veronika G., Rataj-Guranowska, M., Walkowiak, I., (Bud) Platt, H. W., Robb, J., Nazar, R., Hu, X., Fitt, B. D. L., Melo, I. S., Brar, J. K., Huang, H. C., Kozub, G. C., Kokko, E. G., Coomber, S., Bejarano-Alcazar, J., Bianco-Lopez, M. A., Melero-Vara, J. M., Jiménez-Díaz, R. M., Lamers, J. G., Orenstein, Jana, Sabbah, S., Nachmias, A., Livescu, L., Tsror (Lahkim), Leah, Ben-Hador, G., Orion, D., Allen, S. J., Koike, S. T., Subbarao, K. V., Anne Hawke, Mary, Lazarovits, George, Mol, L., Ann Hawke, Mary, Termorshuizen, A. J., Dube, H. C., Ten, L. N., Faiziev, M. M., Romanova, L. A., Resende, Mario L. V., Cooper, Richard M., Flood, Julie, Beale, Michael H., Xu, H., Nazar, R. N., Pennypacker, B. W., Knievel, D. P., Risius, M. L., Leath, K. T., Gold, J., Ciccarese, F., Cirulli, M., Amenduni, M., Eldon, S., Hillocks, R. J., Chambers, D. A., Darby, P., Shadmanov, R. K., Hiemstra, J. A., Maharshak, G., Klein, L., Sadan, D., Gamliel, A., Grinstein, A., Peretz, I., Katan, J., Heiman, O., Varshavski, S., Melouk, H. A., Li, X., Damicone, J. P., Jackson, K. E., Fravel, D. R., Tjamos, E. C., Nagtzaam, M. P. M., Saito, E. S., Azevedo, J. L., Faull, J. L., Solarska, Ewa, Powelson, M. L., Cappaert, M. R., Christensen, N. W., Huisman, O. C., Davis, J. R., Sorensen, L. H., Schneider, A. T., Wysoki, M., Margalit, J., Zaritsky, A., Barak, Z., Markus, A., Boussiba, S., Cohen, S., Grinberg, M., Manasherob, R., Ben, E., Gazit, E., Oren, Z., Shai, Y., Peleg, N., Nissan, G., Navon, A., Keller, M., Strizhov, N., Regev, Avital, Sneh, B., Koncz, C., Schell, J., Zilberstein, Avian, Chejanovsky, N., Zilberberg, N., Zlotkin, E., Rivkin, H., Gurevitz, M., Faktor, O., Ben-Ze’ev, I. S., Gindin, Galina, Barash, I., Raccah, B., and Glazer, I.

Published
1995
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16. Factorial Stability of Academically Relevant Affective Characteristics

Author

Khan, S. B. and Roberts, D. M.

Abstract

This is an examination of the structural stability of affective characteristics relevant to education over a period of approximately seven months. Results indicated that the six interpretable factors were differentially stable over the time intervals. (Author)

Published
1971

22. Flk-1 Inhibition Modulates the Fit-1 Mutant Phenotype during Blood Vessel Formation

Author

Roberts, D. M., Johnson, J. H., Rosenberg, M. P., and Bautch, V. L.

Subjects
Blood vessels -- Physiological aspects, Protein tyrosine kinase -- Physiological aspects, Cell culture -- Physiological aspects, Biological sciences
Abstract

Flk-1 and Flt-1 are two related receptor tyrosine kinases implicated in blood vessel development. The Flt-1-/- ES cell culture phenotype is characterized by an overgrowth of endothelial cells, resulting in the formation of large endothelial sheets. Since Flk-1 is proposed to be a positive regulator of endothelial cell proliferation, we hypothesized that selectively abrogating Flk-1 activity during in vitro differentiation might rescue the Flt-1-/- overgrowth phenotype. Using the Flk-1-selective inhibitor SU5416, we observed that partial rescue of the Flt-1-/- overgrowth phenotype can be achieved by treating Flt-1 -/- ES cell cultures with 1.0 [micro]M SU5416 starting on day 5 of differentiation. Higher concentrations of SU5416 dramatically decrease endothelial cell numbers and result in the formation of vascular balls and fragments that fail to undergo branching characteristic of a normal vascular plexus. Similar trends were observed in SU5416-treated wild-type cultures. Currently, we are analyzing the Flk-1 phosphorylation status in SU5416-treated Flt-1-/- cultures to directly correlate rescue of the Flt-1-/- phenotype with inhibition of Flk-1 phosphorylation. We conclude that partial rescue of the Flt-1-/- overgrowth phenotype can be achieved through treatment with the Flk-1-selective inhibitor SU5416, suggesting that Flt-1 normally acts to antagonize Flk-1 function.

Published
2001

24. Infantile Colic

Author

Roberts, D M and Ostapchuk, M

Abstract

Infantile colic can be distressing to parents whose infant is inconsolable during crying episodes. Colic is often defined by the “rule of three”: crying for more than three hours per day, for more than three days per week, and for longer than three weeks in an infant who is well-fed and otherwise healthy. The physician's role is to ensure that there is no organic cause for the cry-ing, offer balanced advice on treatments, and provide support to the family. Colic is a diagnosis of exclusion that is made after performing a careful history and physical examination to rule out less common organic causes. Treatment is limited. Feeding changes usually are not advised. Medications available in the United States have not been proved effective in the treatment of colic, and most behaviour interventions have not been proved to be more effective than placebo. Families may turn to untested resources for help, and the physician should offer sound advice about these treatments. Above all, parents need reassurance that their baby is healthy and that colic is self-limited with no long-term adverse effects. Physicians should watch for signs of continuing distress in the child and family, particularly in families whose resources are strained already. South African Family Practice Vol. 49 (1) 2006: pp. 44-47

Published
2007

27. A Vascular Gene Trap Screen Defines RasGRP3 as an Angiogenesis-Regulated Gene Required for the Endothelial Response to Phorbol Esters

Author

Hidaka, M., Swetenburg, R. L., Patterson, C., Bautch, V. L., Anderson, A. L., Stanford, W. L., and Roberts, D. M.

Abstract

We identified Ras guanine-releasing protein 3 (RasGRP3) as a guanine exchange factor expressed in blood vessels via an embryonic stem (ES) cell-based gene trap screen to identify novel vascular genes. RasGRP3 is expressed in embryonic blood vessels, down-regulated in mature adult vessels, and reexpressed in newly formed vessels during pregnancy and tumorigenesis. This expression pattern is consistent with an angiogenic function for RasGRP3. Although a loss-of-function mutation in RasGRP3 did not affect viability, RasGRP3 was up-regulated in response to vascular endothelial growth factor (VEGF) stimulation of human umbilical vein endothelial cells, placing RasGRP3 regulation downstream of VEGF signaling. Phorbol esters mimic the second messenger diacylglycerol (DAG) in activating both protein kinase C (PKC) and non-PKC phorbol ester receptors such as RasGRP3. ES cell-derived wild-type blood vessels exposed to phorbol myristate acetate (PMA) underwent extensive aberrant morphogenesis that resulted in the formation of large endothelial sheets rather than properly branched vessels. This response to PMA was completely dependent on the presence of RasGRP3, as mutant vessels were refractory to the treatment. Taken together, these findings show that endothelial RasGRP3 is up-regulated in response to VEGF stimulation and that RasGRP3 functions as an endothelial cell phorbol ester receptor in a pathway whose stimulation perturbs normal angiogenesis. This suggests that RasGRP3 activity may exacerbate vascular complications in diseases characterized by excess DAG, such as diabetes.

Published
2004
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38. Microbial properties and nitrogen contents of arable soils under different tillage regimes.

Author

Sun, B., Roberts, D. M., Dennis, P. G., Caul, S., Daniell, T. J., Hallett, P. D., and Hopkins, D. W.

Subjects
NITROGEN in soils, TILLAGE research, SOIL microbiology, BIOMASS, PLOWING (Tillage)
Abstract

Attention is being paid to the use of different tillage regimes as a means of retaining soil organic carbon ( SOC) and sequestering more SOC. Alongside earlier measurements of total SOC stocks under different tillage regimes, we have examined the distribution of nitrogen ( N), microbial activity and the structure of the soil bacterial community from differently tilled plots under continuous barley. The plots were established 5 yr before sampling and have been maintained annually under conventional tillage ( CT; moldboard ploughing to 20 cm and disking), deep ploughing ( DP; ploughing to 40 cm and disking), minimum tillage ( MT; disking to 7 cm) or zero tillage ( ZT). Our earlier work showed there was no difference in SOC contents down to 60-cm depth between the treatments, but now we report that there were significant differences in the total N and active microbial biomass (substrate-induced respiration) contents of the same soils. The N contents of the CT, DP and MT treatments were not significantly different, but the ZT contained significantly more N, indicating either greater N retention under the ZT treatment or preferential loss from the more intensively tilled treatments, or a combination of both. The microbial biomass content was greater for the CT and DP treatments than for the MT and ZT treatments, indicating greater sensitivity to treatment effects of the microbial biomass pool than the total C pool, consistent with its more dynamic nature. Terminal restriction fragment length polymorphism ( T- RFLP) analyses of the soil bacteria DNA (a method of assessing the bacterial community structure) enabled the samples to be distinguished both according to SOC content, which is to be expected, and to tillage regime with the greatest differences in community structure occurring in the ZT treatment and the least in DP and CT treatments, reflecting the degree of homogenization or disturbance resulting from tillage. [ABSTRACT FROM AUTHOR]

Published
2014
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49. Postcard: Hand Written Message Requesting the Amount of a Note

Author

Roberts, D. M., Roberts, D. M., Roberts, D. M., and Roberts, D. M.

Abstract

This black and white printed postcard contains correspondence from a man to the 1st National Bank at Holton, Kansas. Handwriting is on the front and the back of the card.

Published
1885

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