2,201,810 research outputs found
On the duration of long GRBs: effects of black hole spin
In the frame of the collapsar model for long gamma ray bursts (GRBs), we
investigate the formation of a torus around a spinning BH and we check what
rotational properties a progenitor star must have in order to sustain torus
accretion over relatively long activity periods. We also study the time
evolution of the BH spin parameter. We take into account the coupling between
BH mass, its spin parameter and the critical specific angular momentum of
accreting gas, needed for the torus to form. The large BH spin reduces the
critical angular momentum which in turn can increase the GRB duration with
respect to the Schwarzschild BH case. We quantify this effect and estimate the
GRB durations in three cases: when a hyper accreting torus operates or a BH
spins very fast or both. We show under what conditions a given progenitor star
produces a burst that can last as short as several seconds and as long as
several hundred of seconds. Our models indicate that it is possible for a
single collapse to produce three kinds of jets: (1) a very short, lasting
between a fraction of a second and a few seconds, 'precursor' jet, powered only
by a hyper accreting torus before the BH spins up, (2) an 'early' jet, lasting
several tens of seconds and powered by both hyper accretion and BH rotation,
and (3) a 'late' jet, powered only by the spinning BH.Comment: 13 pages; 9 figures; ApJ in pres
Kpi form factors and final state interactions in D+ --> K- pi+ pi+ decays
We present a model for the decay D+ --> K- pi+ pi+. The weak interaction part
of this reaction is described using the effective weak Hamiltonian in the
factorisation approach. Hadronic final state interactions are taken into
account through the Kpi scalar and vector form factors fulfilling analyticity,
unitarity and chiral symmetry constraints. The model has only two free
parameters that are fixed from experimental branching ratios. We show that the
modulus and phase of the S wave thus obtained agree nicely with experiment up
to 1.55 GeV. We perform Monte Carlo simulations to compare the predicted Dalitz
plot with experimental analyses. Allowing for a global phase difference between
the S and P waves of -65 degrees, the Dalitz plot of the D+ --> K- pi+ pi+
decay, the Kpi invariant mass spectra and the total branching ratio due to
S-wave interactions are well reproduced.Comment: 24 pages, 4 figures, REVTeX style. A discussion on the isospin 2
component has been included. Two references added. Published in Phys. Rev.
Uniform high irradiance source
New 50 Kw xenon short arc lamp mounted within elliptical collector provides irradiance levels up to 4.4 x 10 to the 7th power watts/sq m with non-uniformity ratio of 3.30. Energy mixer or light pipe between lamp source and target improves non-uniformity to required ratio
Evidence for chaotic behaviour in pulsar spin-down rates
We present evidence for chaotic dynamics within the spin-down rates of 17
pulsars originally presented by Lyne et al. Using techniques that allow us to
re-sample the original measurements without losing structural information, we
have searched for evidence of a strange attractor in the time series of
frequency derivatives for each of the 17 pulsars. We demonstrate the
effectiveness of our methods by applying them to a component of the Lorenz and
R\"ossler attractors that were sampled with similar cadence to the pulsar time
series. Our measurements of correlation dimension and Lyapunov exponent show
that the underlying behaviour appears to be driven by a strange attractor with
approximately three governing non-linear differential equations. This is
particularly apparent in the case of PSR B182811 where a correlation
dimension of 2.06\pm0.03 and a Lyapunov exponent of
inverse days were measured. These results provide an additional diagnostic for
testing future models of this behaviour.Comment: 15 pages, 18 figures, 2 tables, Accepted to MNRA
KEDUDUKAN AHLI WARIS NON MUSLIM DALAM KEWARISAN ISLAM (STUDI KASUS PUTUSAN NOMOR : 1578/PDT.G/2010/PA.JT)
Salah satu pembahasan dalam ilmu mawaris adalah pembahasan
tentang penghalang dalam kewarisan. Penghalang dalam kewarisan ada
tiga penyebabnya yaitu pembunuhan yang disengaja, beda agama dan
perbudakan. Beda agama adalah apabila antara ahli waris dan pewaris
salah satunya beragama Islam dan yang lain tidak beragama Islam.
Tentang perbedaan agama antara pewaris dan ahli waris, dapat
menggugurkan hak seseorang untuk mewarisi harta peninggalan.
Rumusan masalah dalam penelitian ini ialah bagaimana kedudukan
ahli waris non muslim dalam kewarisan Islam dan apakah pertimbangan
Hakim dalam putusan nomor : 1578/Pdt.G/2010/PA.JT telah sesuai
dengan hukum Islam serta Kompilasi Hukum Islam.
Metode pendekatan yang digunakan peneliti adalah library
research (yurudis normatif). Yaitu suatu pendekatan alternatif yang
menganalisa bahan-bahan pustaka di bidang hukum yang norma-
normanya tertulis dan spesifikasi penelitian deskriptis analitis, yaitu
dengan menggunakan metode dan teori ilmu-ilmu sosial tentang hukum
untuk membantu peneliti dalam melakukan analisis.
Hasil dari penelitian ini diperoleh kesimpulan yakni : (1) Hukum
Islam menegaskan prinsip dalam kewarisan bahwa ahli waris non muslim
tidak mempunyai kedudukan untuk mewarisi harta dari pewaris muslim,
sebagaimana yang telah diatur dalam Al-Qur’an, Hadits serta Kompilasi
Hukum Islam. (2) Dalam pertimbangan hakim Pengadilan Agama Jakarta
Timur dianggap telah terjadi kekeliruan mengenai pemahaman tentang
kompetensi absolut Pengadilan Negeri Jakarta Timur yang menetapkan
masalah kewarisan Islam, karena pada dasarnya yang mempunyai
kewenangan absolut ialah Pengadilan Agama Jakarta Timur. Hal tersebut
menimbulkan dasar penolakan hakim Pengadilan Agama menolak
gugatan perkara ahli waris, yang menyebabkan ahli waris non muslim
memperoleh kembali hak kewarisannya. Hasil dari putusan tersebut
ditinjau secara sudut pandang Islam sangat bertentangan dengan Al-
Qur’an dan Hadits serta ketentuan menurut perspektif Kompilasi Hukum
Islam, bahwa mengenai sistem kewarisan Islam tidak mengakui ahli waris
non muslim sebagai ahli waris dari pewaris muslim
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Fuel distribution measurements in a model low NOx double annular combustor using laser induced fluorescence
Planar laser induced fluorescence (PLIF) was employed in a three sector, low NOx double annular combustor in order to characterise the combusting fuel spray. Naphthalene was employed as a fluorescent agent in odourless kerosene in order to determine the behavior of the light fractions in the fuel vapour, and the light to medium fractions in the fuel spray, while 2,5 di-phenyl oxizol (ppo) was employed to determine the behavior of the heavy fractions in the fuel spray. Counter-swirl air blast atomizing fuel injectors employing a nominal fuel spray included cone angle of 90 deg were employed to inject the kerosene fuel into the double annular combustor. Radial and axial measurements were performed on the combusting spray. Spatial variations in fuel spray placement were observed, together with radial anisotropy
Vapor grown silicon dioxide improves transistor base-collector junctions
Vapor grown silicon dioxide layer protects base-collector junction in silicon planar transistors during the emitter diffusion process. This oxide fills in any imperfections that exist in the thermally grown oxide layer and is of greater thickness than that layer. This process is used to deposit protective silicon dioxide coatings on optical surfaces
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The optical characterisation of spray and soot formation in a diesel engine
Laser sheet drop-sizing (LSD) measurements of a Diesel spray and simultaneous laser induced incandescence/Mie scattering measurements of soot have been performed in an optically accessible, common rail, 1.9 litre, turbo-charged, direct injection Diesel engine. The diesel fuel injectors employed in this study were prototype five hole injectors, supplied by R. Bosch. An oxygenated surrogate Diesel fuel with an estimated cetane number of 54 was employed in order to reduce the amount of soot formed during combustion. The prototype five-hole injector employed produced spray jets that were distinguishable in terms of the liquid volume fraction, drop-size distribution and spray penetration distance produced. The soot volume fraction formed during combustion was found to be correlated with drop-size distribution, and local soot particle size distribution was observed to be inversely correlated with local soot volume fraction
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