Monochorionic Twins: A Delicate Balance.

Monochorionic (MC) twins are identical twins who share one placenta, with vascular anastomoses connecting the circulations of both fetuses [...]

The eruptive history and magmatic evolution of Aluto volcano: new insights into silicic peralkaline volcanism in the Ethiopian rift

The silicic peralkaline volcanoes of the East African Rift are some of the least studied volcanoes on Earth. Here we bring together new constraints from fieldwork, remote sensing, geochronology and geochemistry to present the first detailed account of the eruptive history of Aluto, a restless silicic volcano located in a densely populated section of the Main Ethiopian Rift. Prior to the growth of the Aluto volcanic complex (before 500 ka) the region was characterized by a significant period of fault development and mafic fissure eruptions. The earliest volcanism at Aluto built up a trachytic complex over 8 km in diameter. Aluto then underwent large-volume ignimbrite eruptions at 316 ± 19 ka and 306 ± 12 ka developing a ~ 42 km2 collapse structure. After a hiatus of ~ 250 ka, a phase of post-caldera volcanism initiated at 55 ± 19 ka and the most recent eruption of Aluto has a radiocarbon age of 0.40 ± 0.05 cal. ka BP. During this post-caldera phase highly-evolved peralkaline rhyolite lavas, ignimbrites and pumice fall deposits have erupted from vents across the complex. Geochemical modelling is consistent with rhyolite genesis from protracted fractionation (> 80%) of basalt that is compositionally similar to rift-related basalts found east of the complex. Based on the style and volume of recent eruptions we suggest that silicic eruptions occur at an average rate of 1 per 1000 years, and that future eruptions of Aluto will involve explosive emplacement of localised pumice cones and effusive obsidian coulees of volumes in the range 1–100 × 106 m3

Spatial and temporal patterns of deformation at the Tendaho geothermal prospect, Ethiopia

Observations of ground deformation in East Africa have been fundamental for unveiling the tectonics of continental rifting, assessing the seismic and volcanic hazard to development, and identifying geothermal resources. Here we investigate the active natural and anthropogenic processes in the Tendaho Graben, Afar using Interferometric Synthetic Aperture Radar (InSAR) collected by the Envisat satellite in 2004–2010. We used the Poly-Interferometric Rate And time series Estimation (π-RATE) method to calculate displacement in satellite line-of-sight, and a least-square inversion to decompose the line-of-sight displacement into vertical and rift perpendicular components. We observe two zones of deformation: a 20 km wide circular region of subsidence located 10 km northeast of the town of Semera with a maximum displacement rate of ∼5 cm/yr; and elongated zone (50 km) of subsidence in the area of the geothermal prospect, maximum rate of ∼4 cm/yr. The temporal characteristics of subsidence varies between these zones, with an increase in subsidence rate observed in the circular region in August 2008. We used a Bayesian inversion to find the best fitting source models and compared this to locations of seismicity and other geophysical observations. The pattern of deformation is consistent with a combination of magmatic and geothermal processes, but there does not appear to be a direct link to a sequence of dyke intrusions during 2005–2010 at Manda Hararo graben ∼60 km away, but dynamic stress changes or deep crustal flow could account for the observations

PERENCANAAN PENGEMBANGAN BANDAR UDARA DI KABUPATEN NABIRE

Di Kabupaten Nabire untuk menghubungkan daerah-daerah di kecamatan atau distrik yang pada umumnya berada di daerah pedalaman hanya mengandalkan jasa angkutan udara. Saat ini dengan adanya rencana pemekaran Propinsi Papua menjadi tiga Propinsi maka semakin bertambah permintaan perjalanan dan aktivitas pembangunan di berbagai sektor di Kabupaten Nabire maka akan mengalami peningkatan. Bandar udara Nabire tergolong sebagai bandara perintis dengan jenis pesawat yang beroperasi ATR 72-500 sehingga dianggap perlu untuk ditingkatkan kemampuan pelayanannya agar dapat memenuhi permintaan masyarakat serta ikut menunjang pertumbuhan dan perkembangan daerah. Untuk merencanakan pengembangan suatu lapangan terbang harus memperkirakan arus lalu lintas dimasa yang akan datang. Oleh karena itu penelitian yang akan dilakukan bersifat riset. Dengan menganalisa data lima tahun jumlah penumpang, bagasi dan cargo menggunakan analisa regresi dapat diramalkan arus lalu lintas dimasa yang akan datang sehingga pengembangan bandar udara dianggap perlu dilakukan atau tidak. Berdasarkan data-data primer yang diperoleh dari bandara seperti data klimatologi, data karakteristik pesawat, data tanah, keadaan Topografi dan data existing bandara digunakan sebagai acuan merencanakan pengembangan bandar udara. Untuk pengembangan bandar udara Nabire yang akan direncanakan adalah Runway, Taxiway, Apron, Terminal penumpang, Gudang dan Parkir kendaraan. Berdasarkan hasil perhitungan yang mengacu pada standar Internasional Civil Aviation organization (ICAO) dengan pesawat terbang rencana Boeing 737-400 maka dibutuhkan panjang landasan 2.996 meter lebar 45 meter dan jarak antara sumbu landasan pacu dan sumbu landasan hubung adalah 175 meter lebar total taxiway 25 meter dengan tebal perkerasan lentur 80 Cm, luas apron 200 77 m = 15.400 m2, tebal perkerasan rigid pada apron Metode Portland Cemen Asosiation (PCA) = 33 Cm, luas terminal penumpang 127.200 m , luas gudang 880 m dan luas pelataran parkir 21538 m2. Kata kunci: Kabupaten Nabire, Pengembangan Bandar Udara, Runway, Taxiway, Apro

Ductility and compressibility accommodate high magma flux beneath a silicic continental rift caldera:Insights from Corbetti caldera (Ethiopia)

Abstract Large silicic magma reservoirs preferentially form in the upper crust of extensional continental environments. However, our quantitative understanding of the link between mantle magmatism, silicic reservoirs, and surface deformation during rifting is very limited. Here, we focus on Corbetti, a peralkaline caldera in the densely populated Main Ethiopian Rift, which lies above a focused zone of upper mantle partial melt and has been steadily uplifting at a maximum rate of 6.6±1.2 cm yr−1 for more than 10 yr. Numerical modeling shows that a maximum concomitant residual gravity increase of 9±3 μGal yr−1 by the intrusion of mafic magma at ∼7 km depth into a compressible and inelastic crystal mush best explains the observed deformation and gravity changes. The derived magma mass flux of ∼1011 kg yr−1 is anomalously high and at least 1 order of magnitude greater than the mean long‐term mass eruption rate. This study demonstrates that periodic and high‐rate magmatic rejuvenation of upper‐crustal mush is a significant and rapid contributor to mature continental rifting

Pembangunan Jaringan Komputer Nirkabel Dengan Freebsd Sebagai Gateway

Wireless network is a quite new technology in computer network world. It can connect computers without any wire, but it use radio frequency at 2.4 GHz. Today computer network still use wire to connected computers. Wireless is use the air medium, so there is different medium between wire and air. To connect these two medium networks we need other hardware. The hardware is called access point, but there is other problem comes. Access point price is quite expensive, so to handle this problem people were tried to look for another alternative. The alternative is use a personal computer with FreeBSD operating system, but it can\u27t simulate access point perfectly because access point is hardware. It doesn\u27t matter that can\u27t simulate perfectly because not all feature that access point have are use

Shortening of generation cycles in inbred lines of maize (Zea mays L.) through embryo rescue technique

Embryo rescue techniques have been used as an approach to raise hybrids from incompatible crosses. Thesetechniques have also proved to be valuable tools for maize improvement, since they allow reducing the durationof the generation cycles for speed breeding. The aim of this study was to identify an efficient embryo rescueprotocol to evaluate the response of maize (Zea mays L.) embryo culture and compare its generation time (seedto seed) with the generation time of plants obtained by mature seed germination. To this purpose, we evaluatedthe germination efficiency, in vitro protocol efficiency, and days to flowering of three advanced maize inbred linesdeveloped at the National Institute of Agricultural Technology of Argentina. A greenhouse traditional strategywas used as control. The embryo rescue technique allowed obtaining nearly four generations per year comparedto the two generations obtained in greenhouse. All the plants obtained by the embryo rescue technique weremorphologically normal and fertile. The results confirmed the possibility of using embryo rescue strategies tosignificantly reduce the duration of the generation cycles in maize

Improving Classification of Tweets Using Linguistic Information from a Large External Corpus

The bag of words representation of documents is often unsat- isfactory as it ignores relationships between important terms that do not co-occur literally. Improvements might be achieved by expanding the vocabulary with other relevant word, like synonyms. In this paper we use word-word co-occurence information from a large corpus to expand the vocabulary of another corpus consisting of tweets. Several different methods on how to include the co-occurence information are constructed and tested out on the classification of real twitter data. Our results show that we are able to reduce the number of erroneous classifications by 14% using co-occurence information

Current deformation in Central Afar and triple junction kinematics deduced from GPS and InSAR measurements

Kinematics of divergent boundaries and Rift-Rift-Rift junctions are classically studied using long-term geodetic observations. Since significant magma-related displacements are expected, short-term deformation provides important constraints on the crustal mechanisms involved both in active rifting and in transfer of extensional deformation between spreading axes. Using InSAR and GPS data, we analyse the surface deformation in the whole Central Afar region in detail, focusing on both the extensional deformation across the Quaternary magmato-tectonic rift segments, and on the zones of deformation transfer between active segments and spreading axes. The largest deformation occurs across the two recently activated Asal-Ghoubbet (AG) and Manda Hararo-Dabbahu (MH-D) magmato-tectonic segments with very high strain rates, whereas the other Quaternary active segments do not concentrate any large strain, suggesting that these rifts are either sealed during interdyking periods or not mature enough to remain a plate boundary. Outside of these segments, the GPS horizontal velocity field shows a regular gradient following a clockwise rotation of the displacements from the Southeast to the East of Afar, with respect to Nubia. Very few shallow creeping structures can be identified as well in the InSAR data. However, using these data together with the strain rate tensor and the rotations rates deduced from GPS baselines, the present-day strain field over Central Afar is consistent with the main tectonic structures, and therefore with the long-term deformation. We investigate the current kinematics of the triple junction included in our GPS data set by building simple block models. The deformation in Central Afar can be described by adding a central microblock evolving separately from the three surrounding plates. In this model, the northern block boundary corresponds to a deep EW-trending trans-tensional dislocation, locked from the surface to 10–13 km and joining at depth the active spreading axes of the Red Sea and the Aden Ridge, from AG to MH-D rift segments. Over the long-term, this plate configuration could explain the presence of the en-échelon magmatic basins and subrifts. However, the transient behaviour of the spreading axes implies that the deformation in Central Afar evolves depending on the availability of magma supply within the well-established segments