8,732 research outputs found
A Study of Longitudinal Oscillations of Propellant Tanks and Wave Propagations in Feed Lines. Part III - Wave Propagation in an Elastic Pipe Filled with Incompressible Viscous Streaming Fluid
Longitudinal wave propagation in elastic pipe filled with incompressible viscous streaming flui
Casimir Forces and Graphene Sheets
The Casimir force between two infinitely thin parallel sheets in a setting of
such sheets is found. The finite two-dimensional conductivities, which
describe the dispersive and absorptive properties of each sheet, are taken into
account, whereupon the theory is applied to interacting graphenes. By exploring
similarities with in-plane optical spectra for graphite, the conductivity of
graphene is modeled as a combination of Lorentz type oscillators. We find that
the graphene transparency and the existence of a universal constant
conductivity result in graphene/graphene Casimir interaction at
large separations to have the same distance dependence as the one for perfect
conductors but with much smaller magnitude
Uniformization, Calogero-Moser/Heun duality and Sutherland/bubbling pants
Inspired by the work of Alday, Gaiotto and Tachikawa (AGT), we saw the
revival of Poincar{\'{e}}'s uniformization problem and Fuchsian equations
obtained thereof.
Three distinguished aspects are possessed by Fuchsian equations. First, they
are available via imposing a classical Liouville limit on level-two null-vector
conditions. Second, they fall into some A_1-type integrable systems. Third, the
stress-tensor present there (in terms of the Q-form) manifests itself as a kind
of one-dimensional "curve".
Thereby, a contact with the recently proposed Nekrasov-Shatashvili limit was
soon made on the one hand, whilst the seemingly mysterious derivation of
Seiberg-Witten prepotentials from integrable models become resolved on the
other hand. Moreover, AGT conjecture can just be regarded as a quantum version
of the previous Poincar{\'{e}}'s approach.
Equipped with these observations, we examined relations between spheric and
toric (classical) conformal blocks via Calogero-Moser/Heun duality. Besides, as
Sutherland model is also obtainable from Calogero-Moser by pinching tori at one
point, we tried to understand its eigenstates from the viewpoint of toric
diagrams with possibly many surface operators (toric branes) inserted. A
picture called "bubbling pants" then emerged and reproduced well-known results
of the non-critical self-dual c=1 string theory under a "blown-down" limit.Comment: 17 pages, 4 figures; v2: corrections and references added; v3:
Section 2.4.1 newly added thanks to JHEP referee advice. That classical
four-point spheric conformal blocks reproducing known SW prepotentials is
demonstrated via more examples, to appear in JHEP; v4: TexStyle changed onl
Regulation of Chandelier Cell Cartridge and Bouton Development via DOCK7-Mediated ErbB4 Activation
Chandelier cells (ChCs), typified by their unique axonal morphology, are the most distinct interneurons present in cortical circuits. Via their distinctive axonal terminals, called cartridges, these cells selectively target the axon initial segment of pyramidal cells and control action potential initiation; however, the mechanisms that govern the characteristic ChC axonal structure have remained elusive. Here, by employing an in utero electroporation-based method that enables genetic labeling and manipulation of ChCs in vivo, we identify DOCK7, a member of the DOCK180 family, as a molecule essential for ChC cartridge and bouton development. Furthermore, we present evidence that DOCK7 functions as a cytoplasmic activator of the schizophrenia-associated ErbB4 receptor tyrosine kinase and that DOCK7 modulates ErbB4 activity to control ChC cartridge and bouton development. Thus, our findings define DOCK7 and ErbB4 as key components of a pathway that controls the morphological differentiation of ChCs, with implications for the pathogenesis of schizophrenia
Impact of 2000–2050 climate change on fine particulate matter (PM<sub>2.5</sub>) air quality inferred from a multi-model analysis of meteorological modes
Studies of the effect of climate change on fine particulate matter (PM<sub>2.5</sub> air quality using general circulation models (GCMs) show inconsistent results including in the sign of the effect. This reflects uncertainty in the GCM simulations of the regional meteorological variables affecting PM<sub>2.5</sub>. Here we use the CMIP3 archive of data from fifteen different IPCC AR4 GCMs to obtain improved statistics of 21st-century trends in the meteorological modes driving PM<sub>2.5</sub> variability over the contiguous US. We analyze 1999–2010 observations to identify the dominant meteorological modes driving interannual PM<sub>2.5</sub> variability and their synoptic periods T. We find robust correlations (<i>r</i> > 0.5) of annual mean PM<sub>2.5</sub> with T, especially in the eastern US where the dominant modes represent frontal passages. The GCMs all have significant skill in reproducing present-day statistics for T and we show that this reflects their ability to simulate atmospheric baroclinicity. We then use the local PM<sub>2.5</sub>-to-period sensitivity (dPM<sub>2.5</sub>/dT) from the 1999–2010 observations to project PM<sub>2.5</sub> changes from the 2000–2050 changes in T simulated by the 15 GCMs following the SRES A1B greenhouse warming scenario. By weighted-average statistics of GCM results we project a likely 2000–2050 increase of ~ 0.1 μg m<sup>−3</sup> in annual mean PM<sub>2.5</sub> in the eastern US arising from less frequent frontal ventilation, and a likely decrease albeit with greater inter-GCM variability in the Pacific Northwest due to more frequent maritime inflows. Potentially larger regional effects of 2000–2050 climate change on PM<sub>2.5</sub> may arise from changes in temperature, biogenic emissions, wildfires, and vegetation, but are still unlikely to affect annual PM<sub>2.5</sub> by more than 0.5 μg m<sup>−3</sup>
Sound propagation over uneven ground and irregular topography
The acoustic impedance of the surface coverings used in the laboratory experiments on sound diffraction by topographical ridges was determined. The model, which was developed, takes into account full wave effects and the possibility of surface waves and predicts the sound pressure level at the receiver location relative to what would be expected if the flat surface were not present. The sound pressure level can be regarded as a function of frequency, sound speed in air, heights of source and receiver, and horizontal distance from source to receiver, as well as the real and imaginary parts of the surface impedance
Mengurus Perubahan Semasa Perintah Kawalan Pergerakan Bersyarat (PKPB) di Sebuah Sekolah Menengah: Suatu Pemerhatian Awal
Kajian ini menggunakan reka bentuk tinjauan menerusi kaedah pemerhatian di sebuah sekolah menengah dalam daerah Batu Gajah di Negeri Perak. Populasi kajian terdiri daripada 102 orang murid Tingkatan Lima di sekolah tersebut. Pemerhatian dibuat ke atas peserta kajian berdasarkan tempoh masa yang tertentu yang telah ditetapkan. Oleh itu, dari kaedah pemerhatian, keputusan yang diperoleh adalah lebih tepat. Menerusi pemerhatian, Model Kompetensi Kepimpinan Perubahan (MKKP) telah digunakan oleh pengetua semasa berhadapan dengan perubahan dalam tadbir urus sekolah. Perintah Kawalan Pergerakan Bersyarat (PKPB) telah mengubah pembudayaan dan iklim sekolah menerusi kepimpinan pengetua. Kajian dijalankan setelah pembukaan semula sekolah bagi murid yang mengambil peperiksaan SPM dan STPM. Kepimpinan pengetua dapat dilihat menerusi pencapaian matlamat perubahan yang telah dirancang dari awal proses perubahan. Pengetua juga berjaya melakukan perubahan dengan cara yang kreatif dan proaktif terhadap sekolah tersebut. Hal ini dapat dilihat menerusi kepimpinan pengetua dalam menguruskan perubahan sekolah adalah amat penting kerana peranan pengetua sebagai individu yang bertanggungjawab secara langsung ke atas perubahan di sekolah
Threshold production in nucleon-nucleon collisions
We analyze production in nucleon-nucleon collisions near threshold
in the framework of a general model independent formalism, which can be applied
to any reaction , where , , or . Such
reactions show large isotopic effects: a large difference for - and
-collisions, which is due to the different spin structure of the
corresponding matrix elements. The analysis of the spin structure and of the
polarization observables is based on symmetry properties of the strong
interaction. Using existing experimental data on the different decays of
meson, we suggest a model for , based on
channel -exchanges. We predict polarization phenomena for the
-reaction and the ratio of cross sections for and
-collisions. For the processes we apply two
different approaches: vector meson exchange and local four-particle
interaction. In both cases we find larger -production in
-collisions, with respect to -collisions.Comment: 17 pages, 6 figure
High resolution 10 mu spectrometry at different planetary latitudes. A practical Hadamard transform spectrometer for astronomical application
Infrared observations at different latitudes were studied in order to obtain spectra in the 10 micrometers region to understand differences in chemical composition or physical structure of the optical features. In order to receive such spectra of a rotating planet, simultaneous observations at different latitudes were made. A Hadamard transform spectrometer with 15 entrance slits was used to obtain 15 simultaneous spectra, at a resolution of 0.01 micrometers. The spectral band covered contained 255 spectral elements
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