2,384 research outputs found

    Controlled cavity collapse: scaling laws of drop formation

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    The formation of transient cavities at liquid interfaces occurs in an immense variety of natural processes, among which the bursting of surface bubbles and the impact of a drop on a liquid pool are salient. The collapse of a surface liquid cavity is a well documented natural process that leads to the ejection of a thin and fast jet. Droplets generated through this process can be one order of magnitude smaller than the cavity's aperture, and they are consequently of interest in drop on demand inkjet applications. In this work, the controlled formation and collapse of a liquid cavity is analyzed, and the conditions for minimizing the resulting size and number of ejected drops are determined. The experimental and numerical models are simple and consist of a liquid reservoir, a nozzle plate with the discharge orifice, and a moving piston actuated by single half-sine-shaped pull-mode pulses. The size of the jetted droplet is described by a physical model resulting in a scaling law that is numerically and experimentally validated

    Pre-Schoolers’ Home Numeracy and Home Literacy Experiences and Their Relationships with Early Number Skills: Evidence from a UK Study

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    Research Findings. It has been proposed that the home literacy environment may influence the development of early number skills. However, the results of studies examining the association between home literacy experiences and early number skills are mixed. This could be due to the way that the home literacy experiences are conceptualized and measured. This study examines the relationship between early number skills and aspects of the home learning environment. Alongside home number experiences and parental mathematical attitudes, two types of home literacy experiences were examined in a sample of 274 pre-schoolers (mean age 4:0, SD 4 months); code-focused home literacy experiences that focus on the phonological and orthographic features of language, and meaning-focused home literacy experiences that focus on sharing the meaning of language and text. Home number experiences and letter-sound interactions (interactive code-focused literacy experiences) were related to the children’s counting, number transcoding, and calculation skills whereas meaning-focused home literacy experiences and parental mathematical attitudes were largely unrelated to these early number skills. Structural equation models indicated that only letter-sound interactions could predict statistically significant unique variance in counting, number transcoding, and calculation. Practice or Policy. These findings suggest that code– rather than meaning-focused home literacy experiences are related to pre-schoolers early number skills. Supporting parents to engage in code-focused home literacy experiences may benefit pre-schoolers number skills as well as their emergent literacy

    Private Financing or Not, That is the Question: Lessons from the Light Rail Systems in Spain

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    The objective of this paper is to analyze if there is any difference between the light rail systems in Spain according to whether they have been carried out through public financing or private financing (totally or partially). The importance of this study lies in the fact that, for decades, the public–private partnership has been proposed as an alternative to public financing of public transport projects in order to obtain additional financial resources, reduce the public deficit, and increase efficiency. However, there are hardly any detailed studies describing how these initiatives have turned out. Therefore, the present study analyzes if there is any difference in the main variables explaining the performance of light rail projects in Spain depending on their source of funding can be found. For this, the relationship between variables related to design, operation and costs of the projects, and the percentage of private financing were statistically analyzed. As the most relevant conclusion, we underline the fact that the investment per passenger increases when financing is completely private. This would indicate that the most cost-effective lines, from a social standpoint, were financed totally or partially by the public administrations, whereas the least beneficial ones for society were assigned to private enterprises. This finding provides an advance in the knowledge of the consequences of private participation in the financing of public transport projects, indicating, moreover, that the biggest beneficiaries of this type of projects might be the construction companies and the politicians involvedThe authors would like to thank the ERDF of European Union for financial support via project ‘‘Herramienta para la evaluacio®n previa de infraestructuras de transporte pu®blico’’ (GGI3003IDIE). We also thank to Public Works Agency and Regional Ministry of Public Works and Housing of the Regional Government of Andalusia (AOPJA) and the Ministry of Education, Culture and Sports of the Government of Spain

    Unusually thick dinosaur eggshell fragments from the Spanish Late Cretaceous

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    [EN] Fieldwork carried out recently in the southeastern branch of the Iberian Range (Valencia Province, Spain) has led to the collection of a large volume of dinosaur eggshell fragments of unusual thickness. These specimens, up to 4.9 mm thick, were recovered from palustrine grey marls of the upper Campanian-lower Maastrichtian Sierra Perenchiza Formation, which comprises a wetland paleoenvironment deposit. These eggshell fragments have a characteristic compactituberculate ornamentation, dinosauroid-spherulitic organisation, and exhibit a complex canaliculate respiratory system. The external tuberculate surface of the shell as well as the internal microstructure enable referral to Megaloolithus aff. siruguei, the most common megaloolithid oospecies known from the Iberian Peninsula and southern France. The biostratigraphic range of M. siruguei matches the temporal distribution of titanosaurid dinosaurs across the Iberian Range, tentatively considered to be potential producers.This work was supported by the Ministerio de Economia y Competitividad of Spain [Secretaria de Estado de Investigacion, Desarrollo e Innovacion, projects CGL2013-47521-P and CGL2014-53548-P]Company RodrĂ­guez, J. (2017). Unusually thick dinosaur eggshell fragments from the Spanish Late Cretaceous. Historical Biology (Online). 31(2):203-210. https://doi.org/10.1080/08912963.2017.1357717S203210312Allain, R., & Suberbiola, X. P. (2003). Dinosaurs of France. Comptes Rendus Palevol, 2(1), 27-44. doi:10.1016/s1631-0683(03)00002-2Bravo, A. M., & Gaete, R. (2014). Titanosaur eggshells from the Tremp Formation (Upper Cretaceous, Southern Pyrenees, Spain). Historical Biology, 27(8), 1079-1089. doi:10.1080/08912963.2014.934231Canudo, J. I., Oms, O., Vila, B., Galobart, À., Fondevilla, V., PuĂ©rtolas-Pascual, E., 
 Blanco, A. (2016). The upper Maastrichtian dinosaur fossil record from the southern Pyrenees and its contribution to the topic of the Cretaceous–Palaeogene mass extinction event. Cretaceous Research, 57, 540-551. doi:10.1016/j.cretres.2015.06.013Cruzado-Caballero, P., Ruiz-Omeñaca, J. I., Gaete, R., Riera, V., Oms, O., & Canudo, J. I. (2013). A new hadrosaurid dentary from the latest Maastrichtian of the Pyrenees (north Spain) and the high diversity of the duck-billed dinosaurs of the Ibero-Armorican Realm at the very end of the Cretaceous. Historical Biology, 26(5), 619-630. doi:10.1080/08912963.2013.822867Chiappe, L. M., Coria, R. A., Dingus, L., Jackson, F., Chinsamy, A., & Fox, M. (1998). Sauropod dinosaur embryos from the Late Cretaceous of Patagonia. Nature, 396(6708), 258-261. doi:10.1038/24370Company J. 2004. Vertebrados continentales del CretĂĄcico superior (Campaniense-Maastrichtiense) de Valencia [PhD dissertation]. Valencia: Universidad de Valencia.Company, J., & Szentesi, Z. (2012). Amphibians from the Late Cretaceous Sierra Perenchiza Formation of the Chera Basin, Valencia Province, Spain. Cretaceous Research, 37, 240-245. doi:10.1016/j.cretres.2012.04.003Csiki-Sava, Z., Buffetaut, E., Ɛsi, A., Pereda-Suberbiola, X., & Brusatte, S. L. (2015). Island life in the Cretaceous - faunal composition, biogeography, evolution, and extinction of land-living vertebrates on the Late Cretaceous European archipelago. ZooKeys, 469, 1-161. doi:10.3897/zookeys.469.8439Erben, H. K., Hoefs, J., & Wedepohl, K. H. (1979). Paleobiological and isotopic studies of eggshells from a declining dinosaur species. Paleobiology, 5(4), 380-414. doi:10.1017/s0094837300016900GarcĂ­a, R. A. (2007). An «egg-tooth»–like structure in titanosaurian sauropod embryos. Journal of Vertebrate Paleontology, 27(1), 247-252. doi:10.1671/0272-4634(2007)27[247:aesits]2.0.co;2Garcia, G., & Vianey-Liaud, M. (2001). Dinosaur eggshells as biochronological markers in Upper Cretaceous continental deposits. Palaeogeography, Palaeoclimatology, Palaeoecology, 169(1-2), 153-164. doi:10.1016/s0031-0182(01)00215-2Grellet-Tinner, G., Chiappe, L. M., & Coria, R. (2004). Eggs of titanosaurid sauropods from the Upper Cretaceous of Auca Mahuevo (Argentina). Canadian Journal of Earth Sciences, 41(8), 949-960. doi:10.1139/e04-049Grigorescu, D., Garcia, G., Csiki, Z., Codrea, V., & Bojar, A.-V. (2010). Uppermost Cretaceous megaloolithid eggs from the HaĆŁeg Basin, Romania, associated with hadrosaur hatchlings: Search for explanation. Palaeogeography, Palaeoclimatology, Palaeoecology, 293(3-4), 360-374. doi:10.1016/j.palaeo.2010.03.031Izquierdo LA, Montero D, PĂ©rez G, UriĂ©n V, Meijide M. 2001. Macroestructura de huevos de dinosaurios en el CretĂĄcico superior de “La Rosaca” (Burgos, España). Actas de las I Jornadas Internacionales Sobre PaleontologĂ­a de Dinosaurios y su Entorno. Ed. Colectivo ArqueolĂłgico y PaleontolĂłgico de Salas. Salas de los Infantes. p. 389–395.Jackson FD. 2007. Titanosaur reproductive biology: comparison of the Auca Mahuevo Titanosaur nesting locality (Argentina), to the Pinyes Megaloolithus nesting locality (Spain) [PhD dissertation]. Bozeman (MT): Montana State University.Jackson, F. D., Garrido, A., Schmitt, J. G., Chiappe, L. M., Dingus, L., & Loope, D. B. (2004). Abnormal, multilayered titanosaur (Dinosauria: Sauropoda) eggs from in situ clutches at the Auca Mahuevo locality, Neuquen Province, Argentina. Journal of Vertebrate Paleontology, 24(4), 913-922. doi:10.1671/0272-4634(2004)024[0913:amtdse]2.0.co;2Jackson, F. D., Varricchio, D. J., Jackson, R. A., Vila, B., & Chiappe, L. M. (2008). Comparison of water vapor conductance in a titanosaur egg from the Upper Cretaceous of Argentina and a Megaloolithus siruguei egg from Spain. Paleobiology, 34(2), 229-246. doi:10.1666/0094-8373(2008)034[0229:cowvci]2.0.co;2LĂłpez-Martı́nez, N., Moratalla, J. J., & Sanz, J. L. (2000). Dinosaurs nesting on tidal flats. Palaeogeography, Palaeoclimatology, Palaeoecology, 160(1-2), 153-163. doi:10.1016/s0031-0182(00)00063-8Mohabey, D. M. (1998). Systematics of Indian Upper Cretaceous dinosaur and chelonian eggshells. Journal of Vertebrate Paleontology, 18(2), 348-362. doi:10.1080/02724634.1998.10011063Moratalla JJ. 1993. Restos indirectos de dinosaurios del registro español: paleoicnologĂ­a de la Cuenca de (JurĂĄsico superior-CretĂĄcico inferior) y paleoologĂ­a del CretĂĄcico superior [PhD dissertation]. Madrid: Universidad AutĂłnoma de Madrid.Moreno-Azanza, M., Bauluz, B., Canudo, J. I., Gasca, J. M., & Torcida FernĂĄndez-Baldor, F. (2016). Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells. PLOS ONE, 11(5), e0153026. doi:10.1371/journal.pone.0153026Moreno-Azanza, M., Bauluz, B., Canudo, J. I., PuĂ©rtolas-Pascual, E., & SellĂ©s, A. G. (2013). A re-evaluation of aff. Megaloolithidae eggshell fragments from the uppermost Cretaceous of the Pyrenees and implications for crocodylomorph eggshell structure. Historical Biology, 26(2), 195-205. doi:10.1080/08912963.2013.786067Oms, O., DinarĂšs-Turell, J., Vicens, E., Estrada, R., Vila, B., Galobart, À., & Bravo, A. M. (2007). Integrated stratigraphy from the Vallcebre Basin (southeastern Pyrenees, Spain): New insights on the continental Cretaceous−Tertiary transition in southwest Europe. Palaeogeography, Palaeoclimatology, Palaeoecology, 255(1-2), 35-47. doi:10.1016/j.palaeo.2007.02.039Ortega, F., Bardet, N., Barroso-Barcenilla, F., Callapez, P. M., Cambra-Moo, O., Daviero- GĂłmez, V., 
 Sanz, J. L. (2015). The biota of the Upper Cretaceous site of «Lo Hueco» (Cuenca, Spain). Journal of Iberian Geology, 41(1). doi:10.5209/rev_jige.2015.v41.n1.48657Rasskin-Gutman, D., Elez, J., Esteve-Altava, B., & LĂłpez-MartĂ­nez, N. (2020). Reconstruction of the internal structure of the pore system of a complex dinosaur eggshell (Megaloolithus siruguei). Spanish Journal of Palaeontology, 28(1), 61. doi:10.7203/sjp.28.1.17831Riera, V., Oms, O., Gaete, R., & Galobart, À. (2009). The end-Cretaceous dinosaur succession in Europe: The Tremp Basin record (Spain). Palaeogeography, Palaeoclimatology, Palaeoecology, 283(3-4), 160-171. doi:10.1016/j.palaeo.2009.09.018SellĂ©s, A. G., Bravo, A. M., DelclĂČs, X., Colombo, F., MartĂ­, X., Ortega-Blanco, J., 
 Galobart, À. (2013). Dinosaur eggs in the Upper Cretaceous of the Coll de NargĂł area, Lleida Province, south-central Pyrenees, Spain: Oodiversity, biostratigraphy and their implications. Cretaceous Research, 40, 10-20. doi:10.1016/j.cretres.2012.05.004Tanaka, K., & Zelenitsky, D. K. (2014). Comparisons between experimental and morphometric water vapor conductance in the eggs of extant birds and crocodiles: implications for predicting nest type in dinosaurs. Canadian Journal of Zoology, 92(12), 1049-1058. doi:10.1139/cjz-2014-0078Vianey-Liaud, M., Khosla, A., & Garcia, G. (2003). Relationships between European and Indian dinosaur eggs and eggshells of the oofamily Megaloolithidae. Journal of Vertebrate Paleontology, 23(3), 575-585. doi:10.1671/0272-4634(2003)023[0575:rbeaid]2.0.co;2Vianey-Liaud, M., & Lopez-Martinez, N. (1997). Late Cretaceous dinosaur eggshells from the Tremp Basin, southern Pyrenees, Lleida, Spain. Journal of Paleontology, 71(6), 1157-1171. doi:10.1017/s002233600003609xVila, B., Galobart, À., Canudo, J. I., Le Loeuff, J., DinarĂšs-Turell, J., Riera, V., 
 Gaete, R. (2012). The diversity of sauropod dinosaurs and their first taxonomic succession from the latest Cretaceous of southwestern Europe: Clues to demise and extinction. Palaeogeography, Palaeoclimatology, Palaeoecology, 350-352, 19-38. doi:10.1016/j.palaeo.2012.06.008(2010). Lethaia, 43(2). doi:10.1111/let.2010.43.issue-2Vila, B., Jackson, F. D., Fortuny, J., SellĂ©s, A. G., & Galobart, À. (2010). 3-D Modelling of Megaloolithid Clutches: Insights about Nest Construction and Dinosaur Behaviour. PLoS ONE, 5(5), e10362. doi:10.1371/journal.pone.0010362Vila, B., Riera, V., Bravo, A. M., Oms, O., Vicens, E., Estrada, R., & Galobart, À. (2011). The chronology of dinosaur oospecies in south-western Europe: Refinements from the Maastrichtian succession of the eastern Pyrenees. Cretaceous Research, 32(3), 378-386. doi:10.1016/j.cretres.2011.01.009Vila, B., SellĂ©s, A. G., & Brusatte, S. L. (2016). Diversity and faunal changes in the latest Cretaceous dinosaur communities of southwestern Europe. Cretaceous Research, 57, 552-564. doi:10.1016/j.cretres.2015.07.003Vissers, R. L. M., & Meijer, P. T. (2012). Iberian plate kinematics and Alpine collision in the Pyrenees. Earth-Science Reviews, 114(1-2), 61-83. doi:10.1016/j.earscirev.2012.05.001Wright, V. P., & Platt, N. H. (1995). Seasonal wetland carbonate sequences and dynamic catenas: a re-appraisal of palustrine limestones. Sedimentary Geology, 99(2), 65-71. doi:10.1016/0037-0738(95)00080-

    Identifying the preschool home learning experiences that predict early number skills: Evidence from a longitudinal study

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    This study examines the longitudinal relationships between home learning experiences and early number skills. The counting, number transcoding and calculation skills of 274 children were assessed in the penultimate term of preschool (Mage = 4:0). Prior to these assessments, parents completed questionnaires that surveyed the frequency of the children's home learning experiences. Three types of experiences were indexed: code-focused home literacy experiences that focus on the phonological and orthographic features of language, meaning-focused home literacy experiences that focus on sharing the meaning of language and text, and home number experiences. The children's language abilities (phonological awareness and vocabulary) and nonverbal abilities (inhibitory control and nonverbal reasoning) were assessed in the final term of preschool (Mage = 4:3). Their number skills were reassessed in the final term of the first year of primary school (Mage = 5:3). Home letter–sound interaction experiences (interactive code-focused literacy experiences) had significant longitudinal relationships with counting and number transcoding that were independent of language and nonverbal abilities. The relationship between letter–sound interaction experiences and later counting was also independent of the autoregressive influence of baseline counting ability. We extend previous findings by demonstrating that interactive code-focused home literacy experiences in the preschool period predict growth in counting skills even when a broad range of language and cognitive abilities are controlled. Supporting parents to engage in code-focused home literacy experiences may benefit pre-schoolers’ counting skills

    The influence of long-term treadmill exercise on bone mass and articular cartilage in ovariectomized rats

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    <p>Abstract</p> <p>Background</p> <p>Loss of bone quality and deterioration of articular cartilage are commonly seen after menopause. While exercise may protect against tissue degeneration, a clear link has yet to be established. The aim of the present study is to investigate the influence of long-term treadmill exercise on changes in bone mass and articular cartilage in ovariectomized rats.</p> <p>Methods</p> <p>Sixty female Sprague-Dawley rats were randomly assigned to 4 groups: ovariectomized (OVX), ovariectomized plus treadmill exercise (OVX-RUN), treadmill exercise alone (RUN), and control (CON) groups. After 36 weeks, the following variables were compared among the 4 groups. Bone mass was evaluated by trabecular bone volume and bone mineral density (BMD). Articular cartilage in the knee joints was evaluated by histology analysis and a modified Mankin score.</p> <p>Results</p> <p>Rats in the ovariectomized groups (OVX and OVX-RUN) had significantly lower BMD and bone mass than the non-ovariectomized rats (CON and RUN), indicating that exercise did little to preserve bone mass. However, the sedentary OVX group had a significantly worse modified Mankin score (7.7 ± 1.4) than the OVX-RUN group (4.8 ± 1.0), whose scores did not differ significantly from the other 2 non-operated groups. The articular cartilage in the sedentary OVX rats was relatively thinner, hypocellular, and had more clefts than in the other 3 groups.</p> <p>Conclusion</p> <p>This study suggests that long-term exercise protects articular cartilage in OVX rats but does not retard the loss of bone mass seen in after menopause.</p

    The ethics of digital well-being: a multidisciplinary perspective

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    This chapter serves as an introduction to the edited collection of the same name, which includes chapters that explore digital well-being from a range of disciplinary perspectives, including philosophy, psychology, economics, health care, and education. The purpose of this introductory chapter is to provide a short primer on the different disciplinary approaches to the study of well-being. To supplement this primer, we also invited key experts from several disciplines—philosophy, psychology, public policy, and health care—to share their thoughts on what they believe are the most important open questions and ethical issues for the multi-disciplinary study of digital well-being. We also introduce and discuss several themes that we believe will be fundamental to the ongoing study of digital well-being: digital gratitude, automated interventions, and sustainable co-well-being

    Electrostatic charging of jumping droplets

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    With the broad interest in and development of superhydrophobic surfaces for self-cleaning, condensation heat transfer enhancement and anti-icing applications, more detailed insights on droplet interactions on these surfaces have emerged. Specifically, when two droplets coalesce, they can spontaneously jump away from a superhydrophobic surface due to the release of excess surface energy. Here we show that jumping droplets gain a net positive charge that causes them to repel each other mid-flight. We used electric fields to quantify the charge on the droplets and identified the mechanism for the charge accumulation, which is associated with the formation of the electric double layer at the droplet–surface interface. The observation of droplet charge accumulation provides insight into jumping droplet physics as well as processes involving charged liquid droplets. Furthermore, this work is a starting point for more advanced approaches for enhancing jumping droplet surface performance by using external electric fields to control droplet jumping.United States. Dept. of Energy. Office of Basic Energy Sciences (Solid-State Solar-Thermal Energy Conversion Center Award DE-FG02-09ER46577)United States. Office of Naval ResearchNational Science Foundation (U.S.) (Major Research Instrumentation Grant for Rapid Response Research (MRI- RAPID))National Science Foundation (U.S.) (Award ECS-0335765)National Science Foundation (U.S.). Graduate Research Fellowship Program (Grant 1122374
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