746 research outputs found
Test Results of the Modified Space Shuttle Main Engine at the Marshall Space Flight Center Technology Test Bed Facility
A modified space shuttle main engine (SSME), which primarily includes an enlarged throat main combustion chamber with the acoustic cavities removed and a main injector with the stability control baffles removed, was tested. This one-of-a-kind engine's design changes are being evaluated for potential incorporation in the shuttle flight program in the mid-1990's. Engine testing was initiated on September 15, 1988 and has accumulated 1,915 seconds and 19 starts. Testing is being conducted to characterize the engine system performance, combustion stability with the baffle-less injector, and both low pressure oxidizer turbopump (LPOTP) and high pressure oxidizer turbopump (HPOTP) for suction performance. These test results are summarized and compared with the SSME flight configuration data base. Testing of this new generation SSME is the first product from the technology test bed (TTB). Figure test plans for the TTB include the highly instrumented flight configuration SSME and advanced liquid propulsion technology items
Possible alternative mechanism to SUSY: conservative extensions of the Poincar\'e group
A group theoretical mechanism is outlined, which can indecomposably extend
the Poincar\'e group by the compact internal (gauge) symmetries at the price of
allowing some nilpotent (or, more precisely: solvable) internal symmetries in
addition. Due to the presence of this nilpotent part, the prohibitive argument
of the well known Coleman-Mandula and McGlinn no-go theorems do not go through.
In contrast to SUSY or extended SUSY, in our construction the symmetries
extending the Poincar\'e group will be all internal, i.e. they do not act on
the spacetime, merely on some internal degrees of freedom -- hence the name:
conservative extensions of the Poincar\'e group. Using the Levi decomposition
and O'Raifeartaigh theorem, the general structure of all possible conservative
extensions of the Poincar\'e group is outlined, and a concrete example group is
presented with U(1) being the compact gauge group component. It is argued that
such nilpotent internal symmetries may be inapparent symmetries of some more
fundamental field variables, and therefore do not carry an ab initio
contradiction with the present experimental understanding in particle physics.
The construction is compared to (extended) SUSY, since SUSY is somewhat
analogous to the proposed mechanism. It is pointed out, however, that the
proposed mechanism is less irregular in comparison to SUSY, in certain aspects.
The only exoticity needed in comparison to a traditional gauge theory setting
is that the full group of internal symmetries is not purely compact, but is a
semi-direct product of a nilpotent and of a compact part.Comment: 10 pages, contribution to Proceedings of X. International Symposium
on Quantum Theory and Symmetries, Springer (2018
MCP-1 induces cardioprotection against ischaemia/reperfusion injury: role of reactive oxygen species
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in CARDIOVASCULAR RESEARCH 78 (3): 554-562, 2008 following peer review. The definitive publisher-authenticated version is available online at:http://cardiovascres.oxfordjournals.org/cgi/content/abstract/78/3/554.ArticleCARDIOVASCULAR RESEARCH. 78(3): 554-562 (2008)journal articl
Modulation of mucus production by interleukin-13 receptor alpha(2) in the human airway epithelium
The definitive version is available at www.blackwell-synergy.comArticleCLINICAL AND EXPERIMENTAL ALLERGY. 38(1): 122-134 (2008)journal articl
PENILAIAN SIKAP SISWA DALAM PEMBELAJARAN BAHASA INDONESIA OLEH GURU KELAS VII DI SMP NEGERI 1 KOTA BENGKULU
Tujuan penelitian ini untuk mendeskripsikan penilaian sikap dalam pembelajaran Bahasa Indonesia oleh guru kelas VII di SMP Negeri 1 Kota Bengkulu. Jenis penelitian ini adalah kualitatif dengan metode deskriptif. Data dalam penelitian ini adalah pelaksanaan penilaian sikap di kelas, RPP guru, serta dokumen penilaian sikap yang dibuat guru. Sumber data dalam penelitian ini adalah dua orang guru mata pelajaran bahasa Indonesia dan seluruh siswa kelas VII 5 dan VII 8. Teknik pengumpulan data dalam penelitian ini dilakukan melalui tiga langkah, yaitu dokumentasi, observasi, dan wawancara. Penelitian ini menggunakan teknik analisis data model Milles dan Huberman. Hasil penelitian ini menujukkan bahwa Guru Mata Pelajaran Bahasa Indonesia kelas VII di SMPN 1 Kota Bengkulu telah melakukan perencanaan penilaian sikap berdasarkan Kurikulum 2013 dengan mempersiapkan lembar observasi, lembar penilaian diri dan penilaian antar peserta didik. Pelaksanaan penilaian sikap dengan teknik observasi oleh guru Bahasa Indonesia berlangsung secara kontekstual dan terintegrasi saat kegiatan pembelajaran Bahasa Indonesia berlangsung serta pelaksanaan penilaian diri dan penilaian antar peserta didik dilakukan guru satu kali diakhir semester. Pemanfaatan penilaian sikap dengan teknik observasi dilakukan guru langsung setelah mencatat sikap negatif siswa dalam jurnal dengan cara memberikan teguran, nasihat, dan membuat surat perjanjian. Hasil penilaian sikap selama satu semester dilaporkan guru Bahasa Indonesia kepada guru wali kelas.Kata Kunci: Penilaian sikap, kurikulum 2013, pembelajaran Bahasa Indonesi
Propagation of gravity waves and spread F in the low-latitude ionosphere over Tucumán, Argentina, by continuous Doppler sounding: first results
Results of systematic analysis of propagation directions and horizontal velocities of gravity waves (GWs) and spread F structures in low-latitude ionosphere (magnetic inclination ~27°) in Tucumán region, Argentina, are presented. Measurements were carried out by multipoint continuous Doppler system during 1 year from December 2012 to November 2013. It was found that meridian propagation of GWs dominated and that southward propagation prevailed in the local summer. Oblique spread structures observed in Doppler shift spectrograms and associated with spread F propagated roughly eastward at velocities from ~70 to ~180 m/s and were observed at night from ~ September to ~ March. The velocities were computed for 182 events and the azimuths for 64 events. Continuous Doppler sounding makes it possible to analyze more events compared to optical observations often used for propagation studies since the measurements do not depend on weather.Fil: Chum, J.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: Miranda Bonomi, Fernando Alberto. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Electricidad, ElectrĂłnica y ComputaciĂłn. Laboratorio de Telecomunicaciones; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Fišer, J.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: Cabrera, M. A.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Electricidad, ElectrĂłnica y ComputaciĂłn. Laboratorio de Telecomunicaciones; Argentina. Universidad TecnolĂłgica Nacional. Facultad Regional Tucuman; ArgentinaFil: Ezquer, Rodolfo Gerardo. Universidad TecnolĂłgica Nacional. Facultad Regional Tucuman; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de FĂsica. Laboratorio de Ionosfera; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Burešová, D.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: LaštoviÄŤka, J.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: Baše, J.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: Hruška, F.. Institute of Atmospheric Physics; RepĂşblica ChecaFil: Molina, Maria Graciela. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Ciencias de la ComputaciĂłn; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Ise, Juan Eduardo. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Electricidad, ElectrĂłnica y ComputaciĂłn. Laboratorio de Telecomunicaciones; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Cangemi, JosĂ© Ignacio. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y TecnologĂa. Departamento de Electricidad, ElectrĂłnica y ComputaciĂłn. Laboratorio de Telecomunicaciones; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Ĺ indelářová, T.. Institute of Atmospheric Physics; RepĂşblica Chec
Electrolytic depletion interactions
We consider the interactions between two uncharged planar macroscopic
surfaces immersed in an electrolyte solution which are induced by interfacial
selectivity. These forces are taken into account by introducing a depletion
free-energy density functional, in addition to the usual mean-field
Poisson-Boltzmann functional. The minimization of the total free-energy
functional yields the density profiles of the microions and the electrostatic
potential. The disjoining pressure is obtained by differentiation of the total
free energy with respect to the separation of the surfaces, holding the range
and strength of the depletion forces constant. We find that the induced
interaction between the two surfaces is always repulsive for sufficiently large
separations, and becomes attractive at shorter separations. The nature of the
induced interactions changes from attractive to repulsive at a distance
corresponding to the range of the depletion forces.Comment: 17 pages, 4 Postscript figures, submitted to Physical Review
Phase behaviour of a model of colloidal particles with a fluctuating internal state
Colloidal particles are not simple rigid particles, in general an isolated
particle is a system with many degrees of freedom in its own right, e.g., the
counterions around a charged colloidal particle.The behaviour of model
colloidal particles, with a simple phenomenological model to account for these
degrees of freedom, is studied. It is found that the interaction between the
particles is not pairwise additive. It is even possible that the interaction
between a triplet of particles is attractive while the pair interaction is
repulsive. When this is so the liquid phase is either stable only in a small
region of the phase diagram or absent altogether.Comment: 12 pages including 4 figure
The comparative anatomy of the folds, fossae, and adhesions around the duodenojejunal flexure in mammals
Background: Anatomical knowledge of the duodenojejunal flexure is necessary for abdominal surgeries, and also important for physiologic studies about the duodenum. But little is known about the anatomy of this region in mammals. Here, we examined comparative anatomy to understand the anatomical formation of the duodenojejunal flexure in mammals.
Materials and methods: The areas around the duonenojejunal flexure were obÂserved in mouse, rat, dog, pig, and human, and the anatomical structures around the duodenojejunal junction in the animals were compared with those in human.
Results: The superior and inferior duodenal folds, and the superior and inferior duodenal fossae were identified in all examined humans. In pig, the structures were not clearly identified because the duodenum strongly adhered to the retroperitoneum and to the mesocolon. In mouse, rat, and dog, only the plica duodenocolica, which is regarded as the animal counterpart of the superior duoÂdenal fold in human, was identified, and other folds or fossae were not observed, probably because the duodenum was not fixed to the parietal peritoneum in those animals. Transection of the plica duodenocolica could return the normally rotated intestine back to the state of non-rotation in rat.
Conclusions: This study showed the anatomical similarities and dissimilarities of the duodenojejunal flexure among the mammals. Anatomical knowledge of the area is useful for duodenal and pancreatic surgeries, and for animal studies about the duodenum. (Folia Morphol 2018; 77, 2: 286–292
- …