30,216 research outputs found
Properties of nucleon in nuclear matter: once more
We calculate the mass and residue of the nucleon in nuclear matter in the
framework of QCD sum rules using the nucleon's interpolating current with an
arbitrary mixing parameter. We evaluate the effects of the nuclear medium on
these quantities and compare the obtained results with the existing theoretical
predictions. The results are also compared with those obtained in vacuum to
find the shifts in the quantities under consideration. Our calculations show
that these shifts in the mass and residue are about and ,
respectively.Comment: 18 Pages, 2 Tables and 7 Figures, To be appear in EPJ
Scalar and vector self-energies of heavy baryons in nuclear medium
The in-medium sum rules are employed to calculate the shifts in the mass and
residue as well as the scalar and vector self-energies of the heavy and baryons, with Q being or quark. The maximum shift
in mass due to nuclear matter belongs to the baryon and it is found
to be . In the case of residue, it is
obtained that the residue of baryon is maximally affected by the
nuclear medium with the shift .
The scalar and vector self-energies are found to be , , , , , and , ,
, , and
.Comment: 13 Pages, 11 Figures and 5 Table
Positive and negative parity hyperons in nuclear medium
The effects of nuclear medium on the residue, mass and self energy of the
positive and negative parity , and hyperons are
investigated using the QCD sum rule method. In the calculations, the general
interpolating currents of hyperons with an arbitrary mixing parameter are used.
We compare the results obtained in medium with those of the vacuum and
calculate the shifts in the corresponding parameters. It is found that the
shifts on the residues in nuclear matter are over all positive for both the
positive and negative parity hyperons, except for the positive parity
hyperon that the shift is negative. The shifts on the masses of these baryons
are obtained to be negative. The shifts on the residues and masses of negative
parity states are large compared to those of positive parities. The maximum
shift belongs to the residue of the negative parity hyperon. The
vector self-energies gained by the positive parity baryons are large compared
to the negative parities' vector self-energies. The maximum value of the vector
self-energy belongs to the positive parity hyperon. The numerical
values are compared with the existing predictions in the literature.Comment: 20 Pages, 9 Figures and 7 Table
More about the and mesons in nuclear matter
We calculate the shifts in decay constants of the pseudoscalar and
mesons in nuclear medium in the frame work of QCD sum rules. We write those
shifts in terms of the and scattering lengths and an extra
phenomenological parameter entered to calculations. Computing an appreciate
forward scattering correlation function, we derive the QCD sum rules for the
and scattering lengths and the extra phenomenological parameter in
terms of various operators in nuclear medium. We numerically find the values of
the shifts in the decay constants compared to their vacuum values. Using the
sum rules obtained, we also determine the shifts in the masses of these
particles due to nuclear matter and compare the results obtained with the
previous predictions in the literature.Comment: 16 Pages, 4 Figures and 3 Table
The engagement of mature distance students
This is an Accepted Manuscript of an article published by Taylor & Francis in Higher Education Research and Development in 2013, available online: http://www.tandfonline.com/10.1080/07294360.2013.777036.Publishe
Weakly nonlinear subcritical instability of visco-elastic Poiseuille flow
It is well known that the Poiseuille flow of a visco-elastic polymer fluid
between plates or through a tube is linearly stable in the zero Reynolds number
limit, although the stability is weak for large Weissenberg numbers. In this
paper we argue that recent experimental and theoretical work on the instability
of visco-elastic fluids in Taylor-Couette cells and numerical work on channel
flows suggest a scenario in which Poiseuille flow of visco-elastic polymer
fluids exhibits a nonlinear "subcritical" instability due to normal stress
effects, with a threshold which decreases for increasing Weissenberg number.
This proposal is confirmed by an explicit weakly nonlinear stability analysis
for Poiseuille flow of an UCM fluid. Our analysis yields explicit predictions
for the critical amplitude of velocity perturbations beyond which the flow is
nonlinearly unstable, and for the wavelength of the mode whose critical
amplitude is smallest. The nonlinear instability sets in quite abruptly at
Weissenberg numbers around 4 in the planar case and about 5.2 in the
cylindrical case, so that for Weissenberg numbers somewhat larger than these
values perturbations of the order of a few percent in the wall shear stress
suffice to make the flow unstable. We have suggested elsewhere that this
nonlinear instability could be an important intrinsic route to melt fracture
and that preliminary experiments are both qualitatively and quantitatively in
good agreement with these predictions.Comment: 20 pages, 16 figures. Accepted for publication in J. of Non-Newtonian
Fluid Mechanic
Keluarga sebagai Titik Awal Perkembangan Sosial Anak Usia Dini ( sebuah Kajian Sosiologis )
Setiap orang tua menaruh harapan agar putra-putrinya berhasil dalam perkembangan sosialnya, yakni mampu menjadi sosok manusia sosial yang dapat diterima oleh lingkungan sosialnya dan menjadi anggota masyarakat yang bermanfaat bagi kehidupan sesamanya. Orang tua akan merasa gagal manakala putra-putrinya berkembang sebagai manusia yang a-sosial (tidak lumrah/wajar secara sosial ) apalagi sampai menjadi manusia anti - sosial (membuat resah bahkan membahayakan bagi kehidupan masyarakatnya ). Anak usia dini berada pada masa usia paling peka dan adaptif terhadap berbagai stimulus yang datang dari lingkungannya, juga berada pada masa-masa kritis bagi pertumbuhan dan perkembangannya yang akan mempengaruhi tahap perkembangan selanjutnya. Disadari bahwa upaya optimalisasi perkembangan anak usia dini membutuhkan dukungan lingkungan yang kondusif untuk pengasuhan dan pengembangannya. The Consultative Group on Early Chidlhood Care and Development mendefinisikan “Pengasuhan dan Pengembangan Anak Usia Dini “ sebagai suatu kegiatan yang ditujukan bagi orang tua dan anggota keluarga lainnya untuk membina tumbuh kembang anak usia 0-8 tahun secara menyeluruh dengan memberikan rangsangan bagi pengembangan mental, intelektual, emosional, moral dan sosial yang tepat dan benar, agar anak dapat tumbuh dan berkembang secara optimal. Usaha yang dapat dilakukan mencakup pemeliharaan aspek kesehatan, pemberian nutrisi, stimulasi intelektual, penyediaan kesempatan yang luas untuk mengeksplorasi dan belajar secara aktif, pengembangan sosial dan emosional, pengasuhan dan bimbingan anak untuk memahami potensi diri yang dimilikinya serta berperan aktif dalam keluarga dan masyarakat. Oleh sebab itu keluarga diharapkan mampu menjadi lingkungan pendidik pertama dan utama dalam proses pengasuhan dan pengembangan anak usia dini, serta menjadi wahana awal bagi perkembangan sosialnya melalui pengembangan “social skills – socialization” yang berlangsung dalam kehidupan keluarga. Tujuan utama pengembangan sosial pada anak usia dini adalah agar anak dapat mengembangkan pola-pola interaksi sosial secara sukses, terjadi keselarasan antara nilai-nilai social control dan internal control, sehingga mampu berkembang sebagai manusia sosial. Berhasil tidaknya perkembangan sosial anak usia dini akan ditentukan oleh kualitas proses sosialisasinya dalam keluarga, yang menjadi awal penentu keberhasilan perkembangan sosialnya
UBE2QL1 is Disrupted by a Constitutional Translocation Associated with Renal Tumor Predisposition and is a Novel Candidate Renal Tumor Suppressor Gene
Investigation of rare familial forms of renal cell carcinoma (RCC) has led to the identification of genes such as VHL and MET that are also implicated in the pathogenesis of sporadic RCC. In order to identify a novel candidate renal tumor suppressor gene, we characterized the breakpoints of a constitutional balanced translocation, t(5;19)(p15.3;q12), associated with familial RCC and found that a previously uncharacterized gene UBE2QL1 was disrupted by the chromosome 5 breakpoint. UBE2QL1 mRNA expression was downregulated in 78.6% of sporadic RCC and, although no intragenic mutations were detected, gene deletions and promoter region hypermethylation were detected in 17.3% and 20.3%, respectively, of sporadic RCC. Reexpression of UBE2QL1 in a deficient RCC cell line suppressed anchorage-independent growth. UBE2QL1 shows homology to the E2 class of ubiquitin conjugating enzymes and we found that (1) UBE2QL1 possesses an active-site cysteine (C88) that is monoubiquitinated in vivo, and (2) UBE2QL1 interacts with FBXW7 (an F box protein providing substrate recognition to the SCF E3 ubiquitin ligase) and facilitates the degradation of the known FBXW7 targets, CCNE1 and mTOR. These findings suggest UBE2QL1 as a novel candidate renal tumor suppressor gen
Spinodal Instabilities in Nuclear Matter in a Stochastic Relativistic Mean-Field Approach
Spinodal instabilities and early growth of baryon density fluctuations in
symmetric nuclear matter are investigated in the basis of stochastic extension
of relativistic mean-field approach in the semi-classical approximation.
Calculations are compared with the results of non-relativistic calculations
based on Skyrme-type effective interactions under similar conditions. A
qualitative difference appears in the unstable response of the system: the
system exhibits most unstable behavior at higher baryon densities around
in the relativistic approach while most unstable
behavior occurs at lower baryon densities around in
the non-relativistic calculationsComment: 18 pages, 7 figure
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