Newly-Discovered Globular Clusters in NGC 147 and NGC 185 from PAndAS

Using data from the Pan-Andromeda Archaeological Survey (PAndAS), we have discovered four new globular clusters (GCs) associated with the M31 dwarf elliptical (dE) satellites NGC 147 and NGC 185. Three of these are associated with NGC 147 and one with NGC 185. All lie beyond the main optical boundaries of the galaxies and are the most remote clusters yet known in these systems. Radial velocities derived from low resolution spectra are used to argue that the GCs are bound to the dwarfs and are not part of the M31 halo population. Combining PAndAS with UKIRT/WFCAM data, we present the first homogeneous optical and near-IR photometry for the entire GC systems of these dEs. Colour-colour plots and published colour-metallicity relations are employed to constrain GC ages and metallicities. It is demonstrated that the clusters are in general metal poor ([Fe/H] < -1.25 dex), while the ages are more difficult to constrain. The mean (V-I)$_0$ colours of the two GC systems are very similar to those of the GC systems of dEs in the Virgo and Fornax clusters, as well as the extended halo GC population in M31. The new clusters bring the GC specific frequency (S_N) to ~9 in NGC 147 and ~5 in NGC 185, consistent with values found for dEs of similar luminosity residing in a range of environments.Comment: 14 pages, 6 figures, 6 tables, accepted for publication in MNRA

Self-organization of (001) cubic crystal surfaces

Self-organization on crystal surface is studied as a two dimensional spinodal decomposition in presence of a surface stress. The elastic Green function is calculated for a $(001)$ cubic crystal surface taking into account the crystal anisotropy. Numerical calculations show that the phase separation is driven by the interplay between domain boundary energy and long range elastic interactions. At late stage of the phase separation process, a steady state appears with different nanometric patterns according to the surface coverage and the crystal elastic constants

Fabrication and characterisation of nanocrystalline graphite MEMS resonators using a geometric design to control buckling

The simulation, fabrication and characterisation of nanographite MEMS resonators is reported in this paper. The deposition of nanographite is achieved using plasma-enhanced chemical vapour deposition directly onto numerous substrates such as commercial silicon wafers. As a result, many of the reliability issues of devices based on transferred graphene are avoided. The fabrication of the resonators is presented along with a simple undercutting method to overcome buckling, by changing the effective stress of the structure from 436 MPa compressive, to 13 MPa tensile. The characterisation of the resonators using electrostatic actuation and laser Doppler vibrometry is reported, demonstrating resonator frequencies from 5–640 kHz and quality factor above 1819 in vacuum obtained

High-isolation antenna array using SIW and realized with a graphene layer for sub-terahertz wireless applications

This paper presents the results of a study on developing an effective technique to increase the performance characteristics of antenna arrays for sub-THz integrated circuit applications. This is essential to compensate the limited power available from sub-THz sources. Although conventional array structures can provide a solution to enhance the radiation-gain performance however in the case of small-sized array structures the radiation properties can be adversely affected by mutual coupling that exists between the radiating elements. It is demonstrated here the effectiveness of using SIW technology to suppress surface wave propagations and near field mutual coupling effects. Prototype of 2x3 antenna arrays were designed and constructed on a polyimide dielectric substrate with thickness of 125 mu m for operation across 0.19-0.20 THz. The dimensions of the array were 20x13.5x0.125 mm(3). Metallization of the antenna was coated with 500 nm layer of Graphene. With the proposed technique the isolation between the radiating elements was improved on average by 22.5 dB compared to a reference array antenna with no SIW isolation. The performance of the array was enhanced by transforming the patch to exhibit metamaterial characteristics. This was achieved by embedding the patch antennas in the array with sub-wavelength slots. Compared to the reference array the metamaterial inspired structure exhibits improvement in isolation, radiation gain and efficiency on average by 28 dB, 6.3 dBi, and 34%, respectively. These results show the viability of proposed approach in developing antenna arrays for application in sub-THz integrated circuits

Fabrication and characterisation of resistive nanocrystalline graphite

This work demonstrates the feasibility of fabricating resistive nanocrystalline graphite (NCG) on a Si substrate. The NCG film thickness of 9 nm was deposited using metal-free plasma enhanced chemical vapour deposition (PECVD) on a 6-inch p-type silicon wafer. The surface and electrical properties of the resistors produced were investigated. The average grain size of the NCG thin film is 35 nm with 0.8 nm of surface roughness. The electrical characterization of the NCG strips show metal-like behaviour in which the resistance is proportional to the strip lengths. The sheet resistance is found to be 39 kohm/sq which is two orders of magnitude larger than graphene deposited using Chemical Vapour Deposition. This indicates the carrier transport across grain boundaries has a large influence on the overall resistance of the device. However, the nano-sized grains on the NCG material could be used to enhance the sensitivity of the material towards the environment

Newly discovered globular clusters in NGC 147 and NGC 185 from PAndAS

Using data from the Pan-Andromeda Archaeological Survey (PAndAS), we have discovered four new globular clusters (GCs) associated with the M31 dwarf elliptical (dE) satellites NGC 147 and NGC 185. Three of these are associated with NGC 147 and one with NG

Movement patterns of forest elephants (Loxodonta cyclotis Matschie, 1900) in the Odzala-Kokoua National Park, Republic of Congo

[Otros] Les éléphants de forêt d'Afrique (Loxodonta cyclotis Matschie, 1900) sont des ingénieurs en écologie qui jouent un rôle fondamental dans la dynamique de la végétation. L'espèce constitue une préoccupation immédiate pour la conservation, mais elle est relativement peu étudiée. Pour combler cette lacune de connaissances, nous avons étudié les facteurs de déplacements quotidiens (déplacements linéaires) des éléphants de forêt ¿ caractérisés par un ensemble de variables géographiques, météorologiques et anthropiques ¿ dans le Parc National d'Odzala¿Kokoua, en République du Congo. Concrètement, nous avons utilisé la forêt d'arbres décisionnels pour modéliser et démêler les principaux facteurs environnementaux régissant les déplacements de six éléphants de forêt, équipés de colliers GPS et suivis pendant 16 mois. Les résultats ont montré que les femelles se déplaçaient plus loin que les mâles, tandis que la présence de routes ou d¿établissements humains perturbait le comportement des éléphants, ce qui accélérait les déplacements. Les éléphants de forêt se déplaçaient plus rapidement dans les cours d¿eau et dans les forêts dont le sous¿bois était dominé par les forêts de Marantaceae et les bais, mais se déplaçait plus lentement dans les savanes. Enfin, les zones inondables ¿ characterisées par l¿altitude et les précipitations accumulées ¿ et les températures plus élevées empêchaient des déplacements plus longs. Nous espérons que ces résultats amélioreront les connaissances sur les mouvements des espèces à travers différents habitats, ce qui serait bénéfique pour la gestion de leur conservation.[EN] African forest elephants (Loxodonta cyclotis Matschie, 1900) are ecological engineers that play a fundamental role in vegetation dynamics. The species is of immediate conservation concern, yet it is relatively understudied. To narrow this knowledge gap, we studied the drivers of daily movement patterns (linear displacements) of forest elephants¿characterised by a set of geographical, meteorological and anthropogenic variables¿in the Odzala¿Kokoua National Park, Republic of Congo. Explicitly, we used conditional random forest to model and disentangle the main environmental factors governing the displacements of six forest elephants,fitted with GPS collars and tracked over 16 months. Results indicated that females moved further distances than males, while the presence of roads or human settlements disrupted elephant behaviour resulting in faster displacements. Forest elephants moved faster along watercourses and through forest with understory dominated by Marantaceae forests and bais, but moved slower in savannahs. Finally, flood¿prone areas¿described by elevation and accumulated precipitation¿and higher temperatures prevented longer displacements. We expect these results to improve the knowledge on the species movements through different habitats, which would benefit its conservation management.The fieldwork was financed by African Parks. We are grateful to the Congolese wildlife authorities (Ministère de l'Économie Forestière et de l'Environnement) for the permission to carry out this study, and we are deeply indebted to the director of the OKNP and to the conservation, wildlife monitoring and research manager, Erik Marav, respectively, for their continued support during our study. We are particularly grateful to Dr. Mike Kock, veterinarian, for collaring the elephants and to the field tracking team. We are also grateful to Séan Cahill for the useful comments and English correction that helped improve this manuscript. The authors of the present study certify that they have no affiliations with or involvement in any organisation or entity with any financial or nonfinancial interest in the subject matter or materials discussed in this manuscript.Molina-Vacas, G.; Muñoz-Mas, R.; Martinez-Capel, F.; Rodriguez-Teijeiro, JD.; Le Fohlic, G. (2019). Movement patterns of forest elephants (Loxodonta cyclotis Matschie, 1900) in the Odzala-Kokoua National Park, Republic of Congo. African Journal of Ecology. 58:23-33. https://doi.org/10.1111/aje.12695S233358Arlot, S., & Celisse, A. (2010). A survey of cross-validation procedures for model selection. Statistics Surveys, 4(0), 40-79. doi:10.1214/09-ss054Bermejo, M. (1999). Status and conservation of primates in Odzala National Park, Republic of the Congo. Oryx, 33(4), 323-331. doi:10.1046/j.1365-3008.1999.00081.xBirkett, P. J., Vanak, A. T., Muggeo, V. M. R., Ferreira, S. M., & Slotow, R. (2012). Animal Perception of Seasonal Thresholds: Changes in Elephant Movement in Relation to Rainfall Patterns. PLoS ONE, 7(6), e38363. doi:10.1371/journal.pone.0038363Blake, S., Deem, S. L., Strindberg, S., Maisels, F., Momont, L., Isia, I.-B., … Kock, M. D. (2008). Roadless Wilderness Area Determines Forest Elephant Movements in the Congo Basin. PLoS ONE, 3(10), e3546. doi:10.1371/journal.pone.0003546Blake, S., Douglas-Hamilton, I., & Karesh, W. B. (2001). GPS telemetry of forest elephants in Central Africa: results of a preliminary study. African Journal of Ecology, 39(2), 178-186. doi:10.1046/j.1365-2028.2001.00296.xBlake, S., Strindberg, S., Boudjan, P., Makombo, C., Bila-Isia, I., Ilambu, O., … Maisels, F. (2007). Forest Elephant Crisis in the Congo Basin. PLoS Biology, 5(4), e111. doi:10.1371/journal.pbio.0050111Bohrer, G., Beck, P. S., Ngene, S. M., Skidmore, A. K., & Douglas-Hamilton, I. (2014). Elephant movement closely tracks precipitation-driven vegetation dynamics in a Kenyan forest-savanna landscape. Movement Ecology, 2(1). doi:10.1186/2051-3933-2-2Breiman, L. (2001). Machine Learning, 45(1), 5-32. doi:10.1023/a:1010933404324Breuer, T., Maisels, F., & Fishlock, V. (2016). The consequences of poaching and anthropogenic change for forest elephants. Conservation Biology, 30(5), 1019-1026. doi:10.1111/cobi.12679Buij, R., McShea, W. J., Campbell, P., Lee, M. E., Dallmeier, F., Guimondou, S., … Alonso, A. (2007). Patch-occupancy models indicate human activity as major determinant of forest elephant Loxodonta cyclotis seasonal distribution in an industrial corridor in Gabon. Biological Conservation, 135(2), 189-201. doi:10.1016/j.biocon.2006.10.028CLARK, C. J., POULSEN, J. R., MALONGA, R., & ELKAN, Jr., P. W. (2009). Logging Concessions Can Extend the Conservation Estate for Central African Tropical Forests. Conservation Biology, 23(5), 1281-1293. doi:10.1111/j.1523-1739.2009.01243.xCrooks, K. R., Burdett, C. L., Theobald, D. M., King, S. R. B., Di Marco, M., Rondinini, C., & Boitani, L. (2017). Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals. Proceedings of the National Academy of Sciences, 114(29), 7635-7640. doi:10.1073/pnas.1705769114De Beer, Y., & van Aarde, R. J. (2008). Do landscape heterogeneity and water distribution explain aspects of elephant home range in southern Africa’s arid savannas? Journal of Arid Environments, 72(11), 2017-2025. doi:10.1016/j.jaridenv.2008.07.002De Knegt, H. J., van Langevelde, F., Skidmore, A. K., Delsink, A., Slotow, R., Henley, S., … Prins, H. H. T. (2010). The spatial scaling of habitat selection by African elephants. Journal of Animal Ecology, 80(1), 270-281. doi:10.1111/j.1365-2656.2010.01764.xDi Marco, M., Buchanan, G. M., Szantoi, Z., Holmgren, M., Grottolo Marasini, G., Gross, D., … Rondinini, C. (2014). Drivers of extinction risk in African mammals: the interplay of distribution state, human pressure, conservation response and species biology. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1643), 20130198. doi:10.1098/rstb.2013.0198Vladimir, D., & Jon, H. (2018). Mammalwatching: A new source of support for science and conservation. International Journal of Biodiversity and Conservation, 10(4), 154-160. doi:10.5897/ijbc2017.1162Elliot, N. B., Cushman, S. A., Loveridge, A. J., Mtare, G., & Macdonald, D. W. (2014). Movements vary according to dispersal stage, group size, and rainfall: the case of the African lion. Ecology, 95(10), 2860-2869. doi:10.1890/13-1793.1Fishlock, V., & Lee, P. C. (2013). Forest elephants: fission–fusion and social arenas. Animal Behaviour, 85(2), 357-363. doi:10.1016/j.anbehav.2012.11.004Friedman, J. H. (2001). machine. The Annals of Statistics, 29(5), 1189-1232. doi:10.1214/aos/1013203451GOBUSH, K. S., MUTAYOBA, B. M., & WASSER, S. K. (2008). Long-Term Impacts of Poaching on Relatedness, Stress Physiology, and Reproductive Output of Adult Female African Elephants. Conservation Biology, 22(6), 1590-1599. doi:10.1111/j.1523-1739.2008.01035.xGoldenberg, S. Z., Douglas-Hamilton, I., Daballen, D., & Wittemyer, G. (2016). Challenges of using behavior to monitor anthropogenic impacts on wildlife: a case study on illegal killing of African elephants. Animal Conservation, 20(3), 215-224. doi:10.1111/acv.12309Goldenberg, S. Z., Douglas-Hamilton, I., & Wittemyer, G. (2018). Inter-generational change in African elephant range use is associated with poaching risk, primary productivity and adult mortality. Proceedings of the Royal Society B: Biological Sciences, 285(1879), 20180286. doi:10.1098/rspb.2018.0286Gonzalez-Voyer, A., González-Suárez, M., Vilà, C., & Revilla, E. (2016). Larger brain size indirectly increases vulnerability to extinction in mammals. Evolution, 70(6), 1364-1375. doi:10.1111/evo.12943Graham, M. D., Douglas-Hamilton, I., Adams, W. M., & Lee, P. C. (2009). The movement of African elephants in a human-dominated land-use mosaic. Animal Conservation, 12(5), 445-455. doi:10.1111/j.1469-1795.2009.00272.xHarris, G., Thirgood, S., Hopcraft, J., Cromsight, J., & Berger, J. (2009). Global decline in aggregated migrations of large terrestrial mammals. Endangered Species Research, 7, 55-76. doi:10.3354/esr00173Hothorn, T., Hornik, K., & Zeileis, A. (2006). Unbiased Recursive Partitioning: A Conditional Inference Framework. Journal of Computational and Graphical Statistics, 15(3), 651-674. doi:10.1198/106186006x133933Johnson, D. D. P., Kays, R., Blackwell, P. G., & Macdonald, D. W. (2002). Does the resource dispersion hypothesis explain group living? Trends in Ecology & Evolution, 17(12), 563-570. doi:10.1016/s0169-5347(02)02619-8Kolowski, J. M., Blake, S., Kock, M. D., Lee, M. E., Henderson, A., Honorez, A., & Alonso, A. (2010). Movements of four forest elephants in an oil concession in Gabon, Central Africa. African Journal of Ecology, 48(4), 1134-1138. doi:10.1111/j.1365-2028.2009.01204.xLAURANCE, W. F., CROES, B. M., TCHIGNOUMBA, L., LAHM, S. A., ALONSO, A., LEE, M. E., … ONDZEANO, C. (2006). Impacts of Roads and Hunting on Central African Rainforest Mammals. Conservation Biology, 20(4), 1251-1261. doi:10.1111/j.1523-1739.2006.00420.xLoarie, S. R., Aarde, R. J. V., & Pimm, S. L. (2009). Fences and artificial water affect African savannah elephant movement patterns. Biological Conservation, 142(12), 3086-3098. doi:10.1016/j.biocon.2009.08.008Maisels, F., Strindberg, S., Blake, S., Wittemyer, G., Hart, J., Williamson, E. A., … Amsini, F. (2013). Devastating Decline of Forest Elephants in Central Africa. PLoS ONE, 8(3), e59469. doi:10.1371/journal.pone.0059469May, R., Dandy, G., & Maier, H. (2011). Review of Input Variable Selection Methods for Artificial Neural Networks. Artificial Neural Networks - Methodological Advances and Biomedical Applications. doi:10.5772/16004Metsio Sienne, J., Buchwald, R., & Wittemyer, G. (2013). Differentiation in mineral constituents in elephant selected versus unselected water and soil resources at Central African bais (forest clearings). European Journal of Wildlife Research, 60(2), 377-382. doi:10.1007/s10344-013-0781-0Mills, E. C., Poulsen, J. R., Fay, J. M., Morkel, P., Clark, C. J., Meier, A., … White, L. J. T. (2018). Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon. PLOS ONE, 13(7), e0199387. doi:10.1371/journal.pone.0199387Muñoz-Mas, R., Fukuda, S., Pórtoles, J., & Martínez-Capel, F. (2018). Revisiting probabilistic neural networks: a comparative study with support vector machines and the microhabitat suitability for the Eastern Iberian chub (Squalius valentinus). Ecological Informatics, 43, 24-37. doi:10.1016/j.ecoinf.2017.10.008Muñoz-Mas, R., Fukuda, S., Vezza, P., & Martínez-Capel, F. (2016). Comparing four methods for decision-tree induction: A case study on the invasive Iberian gudgeon ( Gobio lozanoi ; Doadrio and Madeira, 2004). Ecological Informatics, 34, 22-34. doi:10.1016/j.ecoinf.2016.04.011Poulsen, J. R., Koerner, S. E., Moore, S., Medjibe, V. P., Blake, S., Clark, C. J., … White, L. J. T. (2017). Poaching empties critical Central African wilderness of forest elephants. Current Biology, 27(4), R134-R135. doi:10.1016/j.cub.2017.01.023Poulsen, J. R., Rosin, C., Meier, A., Mills, E., Nuñez, C. L., Koerner, S. E., … Sowers, M. (2018). Ecological consequences of forest elephant declines for Afrotropical forests. Conservation Biology, 32(3), 559-567. doi:10.1111/cobi.13035Ripple, W. J., Abernethy, K., Betts, M. G., Chapron, G., Dirzo, R., Galetti, M., … Young, H. (2016). Bushmeat hunting and extinction risk to the world’s mammals. Royal Society Open Science, 3(10), 160498. doi:10.1098/rsos.160498Sánchez‐Montoya, M. M., Moleón, M., Sánchez‐Zapata, J. A., & Tockner, K. (2016). Dry riverbeds: corridors for terrestrial vertebrates. Ecosphere, 7(10). doi:10.1002/ecs2.1508Schuttler, S. G., Blake, S., & Eggert, L. S. (2012). Movement Patterns and Spatial Relationships Among African Forest Elephants. Biotropica, 44(4), 445-448. doi:10.1111/j.1744-7429.2012.00889.xSHORT, J. C. (1983). Density and seasonal movements of forest elephant (Loxodonta africana cyclotis, Matschie) in Bia National Park, Ghana. African Journal of Ecology, 21(3), 175-184. doi:10.1111/j.1365-2028.1983.tb01179.xSnyman, S. L. (2012). The role of tourism employment in poverty reduction and community perceptions of conservation and tourism in southern Africa. Journal of Sustainable Tourism, 20(3), 395-416. doi:10.1080/09669582.2012.657202Stokes, E. J., Strindberg, S., Bakabana, P. C., Elkan, P. W., Iyenguet, F. C., Madzoké, B., … Rainey, H. J. (2010). Monitoring Great Ape and Elephant Abundance at Large Spatial Scales: Measuring Effectiveness of a Conservation Landscape. PLoS ONE, 5(4), e10294. doi:10.1371/journal.pone.0010294Strobl, C., Boulesteix, A.-L., Zeileis, A., & Hothorn, T. (2007). Bias in random forest variable importance measures: Illustrations, sources and a solution. BMC Bioinformatics, 8(1). doi:10.1186/1471-2105-8-25Strobl, C., Hothorn, T., & Zeileis, A. (2009). Party on! The R Journal, 1(2), 14. doi:10.32614/rj-2009-013Turkalo, A. K. (2013). Estimating forest elephant age. African Journal of Ecology, 51(3), 501-505. doi:10.1111/aje.12087Turkalo, A. K., Wrege, P. H., & Wittemyer, G. (2013). Long-Term Monitoring of Dzanga Bai Forest Elephants: Forest Clearing Use Patterns. PLoS ONE, 8(12), e85154. doi:10.1371/journal.pone.0085154Wasser, S. K., Brown, L., Mailand, C., Mondol, S., Clark, W., Laurie, C., & Weir, B. S. (2015). Genetic assignment of large seizures of elephant ivory reveals Africa’s major poaching hotspots. Science, 349(6243), 84-87. doi:10.1126/science.aaa2457WILLIAMS, T. M. (1990). Heat transfer in elephants: thermal partitioning based on skin temperature profiles. Journal of Zoology, 222(2), 235-245. doi:10.1111/j.1469-7998.1990.tb05674.xWittemyer, G., Northrup, J. M., Blanc, J., Douglas-Hamilton, I., Omondi, P., & Burnham, K. P. (2014). Illegal killing for ivory drives global decline in African elephants. Proceedings of the National Academy of Sciences, 111(36), 13117-13121. doi:10.1073/pnas.1403984111WREGE, P. H., ROWLAND, E. D., THOMPSON, B. G., & BATRUCH, N. (2010). Use of Acoustic Tools to Reveal Otherwise Cryptic Responses of Forest Elephants to Oil Exploration. Conservation Biology, 24(6), 1578-1585. doi:10.1111/j.1523-1739.2010.01559.xYoung, K. D., Ferreira, S. M., & Van Aarde, R. J. (2009). Elephant spatial use in wet and dry savannas of southern Africa. Journal of Zoology, 278(3), 189-205. doi:10.1111/j.1469-7998.2009.00568.

Animal cultures matter for conservation

This is the author accepted manuscript. The final version is available from AAAS via the DOI in this record.No abstrac

High-Isolation Antenna Array Using SIW and Realized with a Graphene Layer for Sub-Terahertz Wireless Applications

This paper presents the results of a study on developing an effective technique to increase the performance characteristics of array antennas for sub-THz integrated circuit applications. This is an essential to compensate the limited power of sub-THz sources. Although conventional array structures can provide a solution to enhance the radiation-gain however in the case of small-sized array structures the radiation properties can be adversely affect due to mutual coupling between the radiating elements. It is demonstrated here the effectiveness of using SIW technology to suppress surface wave propagations and near field mutual coupling. Prototype 2×3 antenna array with dimensions 20×13.5×0.125 mm 3 were designed and constructed on a dielectric substrate with thickness of 125 m for operation across 0.19-0.20 THz. The metallization of the antenna was coated with 500 nm layer of Graphene. With the proposed technique the isolation between the radiating elements was improved on average by 22.5 dB compared to a reference array antenna with no SIW isolation. The performance of the array was enhanced by transforming the patch to exhibit metamaterial characteristics. This was achieved by embedding an array of periodic slots of sub-wavelength in the patch. Compared to the reference array the metamaterial inspired structure exhibits an isolation, radiation gain and efficiency improvement on average by 28.5dB, 6.7dBi, and 36%, respectively. These results show the viability of proposed approach in developing array antennas for application in sub-THz integrated circuits. Keywords: Sub-terahertz (THz) frequency, substrate integrated waveguide (SIW), metamaterial (MTM), high isolation, high gain, graphene-layer, antennas arrays