240 research outputs found
Peripheral fillings of relatively hyperbolic groups
A group theoretic version of Dehn surgery is studied. Starting with an
arbitrary relatively hyperbolic group we define a peripheral filling
procedure, which produces quotients of by imitating the effect of the Dehn
filling of a complete finite volume hyperbolic 3--manifold on the
fundamental group . The main result of the paper is an algebraic
counterpart of Thurston's hyperbolic Dehn surgery theorem. We also show that
peripheral subgroups of 'almost' have the Congruence Extension Property and
the group is approximated (in an algebraic sense) by its quotients obtained
by peripheral fillings. Various applications of these results are discussed.Comment: The difference with the previous version is that Proposition 3.2 is
proved for quasi--geodesics instead of geodesics. This allows to simplify the
exposition in the last section. To appear in Invent. Mat
Twisted Conjugacy Classes in Abelian Extensions of Certain Linear Groups
Given an automorphism , one has an action of
on itself by -twisted conjugacy, namely, . The orbits
of this action are called -twisted conjugacy classes. One says that
has the -property if there are infinitely many
-twisted conjugacy classes for every automorphism of . In
this paper we show that SL and its congruence subgroups have
the -property. Further we show that any (countable) abelian extension
of has the -property where is a torsion free
non-elementary hyperbolic group, or SL, Sp or
a principal congruence subgroup of SL or the fundamental group
of a complete Riemannian manifold of constant negative curvature
Dynamics and Heating of the Magnetic Network on the Sun: Efficiency of mode transformation
We aim to identify the physical processes which occur in the magnetic network
of the chromosphere and which contribute to its dynamics and heating.
Specifically, we study the propagation of transverse (kink) MHD waves which are
impulsively excited in flux tubes through footpoint motions. When these waves
travel upwards, they get partially converted to longitudinal waves through
nonlinear effects (mode coupling). By solving the nonlinear, time-dependent MHD
equations we find that significant longitudinal wave generation occurs in the
photosphere typically for Mach numbers as low as 0.2 and that the onset of
shock formation occurs at heights of about 600 km above the photospheric base.
We also investigate the compressional heating due to longitudinal waves and the
efficiency of mode coupling for various values of the plasma , that
parameterises the magnetic field strength in the network. We find that this
efficiency is maximum for field strengths corresponding to ,
when the kink and tube wave speeds are almost identical. This can have
interesting observational implications. Furthermore, we find that even when the
two speeds are different, once shock formation occurs, the longitudinal and
transverse shocks exhibit strong mode coupling.Comment: 8 pages, 3 figure
The pathology of familial breast cancer: Immunohistochemistry and molecular analysis
Extensive studies of BRCA1- and BRCA2-associated breast tumours have been carried out in the few years since the identification of these familial breast cancer predisposing genes. The morphological studies suggest that BRCA1 tumours differ from BRCA2 tumours and from sporadic breast cancers. Recent progress in immunohistochemistry and molecular biology techniques has enabled in-depth investigation of molecular pathology of these tumours. Studies to date have investigated issues such as steroid hormone receptor expression, mutation status of tumour suppressor genes TP53 and c-erbB2, and expression profiles of cell cycle proteins p21, p27 and cyclin D(1). Despite relative paucity of data, strong evidence of unique biological characteristics of BRCA1-associated breast cancer is accumulating. BRCA1-associated tumours appear to show an increased frequency of TP53 mutations, frequent p53 protein stabilization and absence of imunoreactivity for steroid hormone receptors. Further studies of larger number of samples of both BRCA1- and BRCA2-associated tumours are necessary to clarify and confirm these observations
Resilien usahawan makanan tradisi skala mikro di Beaufort-Membakut sepanjang tempoh Perintah Kawalan Pergerakan (PKP)
Keusahawanan makanan tradisi di Beaufort-Membakut adalah berasaskan makanan suku kaumnya seperti produk makanan tuhau, jeruk bambangan, ambuyat, kuih jala dan kuih sapit. Sejak negara dilanda pandemik COVID-19, pelbagai sektor ekonomi kian merudum sekali gus merencatkan ekonomi skala mikro di daerah ini. Penjualan serta permintaan terhadap produk makanan tradisi kian terjejas memberikan cabaran kepada pengusaha untuk terus bertahan, apatah lagi selepas pelaksanaan Perintah Kawalan Pergerakan (PKP) oleh kerajaan Malaysia. Justeru, timbul persoalan terhadap sejauh manakah pengusaha di daerah ini resilien sepanjang tempoh PKP dilaksanakan. Makalah ini bertujuan untuk mengenal pasti resilien usahawan makanan tradisi skala mikro di Beaufort-Membakut dalam meningkatkan permintaan produk sepanjang tempoh Perintah Kawalan Pergerakan (PKP) dilaksanakan. Reka bentuk kajian yang digunakan ialah pendekatan penerokaan dengan mengaplikasikan kaedah kualitatif sebagai kaedah utama penyelidikan. Teknik pengumpulan data yang digunakan ialah temu bual secara mendalam dengan menggunakan panduan soalan temu bual, temu bual secara tidak langsung dan pemerhatian. Dapatan kajian menunjukkan resilien usahawan makanan tradisi skala mikro sepanjang tempoh PKP adalah (i) berjimat-cermat dalam perbelanjaan, (ii) mengubah norma strategi pemasaran, (iii) tidak membuat pinjaman wang, (iv) menghadkan pengeluaran produk. Sebagai rumusan, usahawan makanan tradisi mempunyai peranan yang signifikan dalam meningkatkan taraf hidup penduduk luar bandar dan melestarikan makanan tradisi suku kaum di negeri Sabah. Secara tidak langsung ia berupaya meningkatkan sumbangan golongan usahawan makanan tradisi kepada ekonomi rumahtangga, kepada komuniti setempat dan akhirnya kepada pembangunan keusahawanan makanan tradisi di peringkat tempatan dan kebangsaan
Maintenance of <I>Francisella tularensis</I> 15 RIEH and <I>Brucella abortus</I> 19 BA Strains in a Viable State by Means of Deep Freezing
Assessed are the methods for storage of microorganisms in a viable state under various technological conditions for a period of two years. Compared is the survivability of the test-strains of tularemia and brucellosis agents (exemplified by Francisella tularensis 15 RIEH and Brucella abortus 19 BA) when stored on the nutrient media at temperatures raging 0 °C up +8 °C and at -70 °C for over a year. Made has been an estimate of survivability of the vaccine strains stored at -70 °C within two years term. It is determined that optimum media for storing the stated above microorganisms with no changes in their morphological characteristics at -70 °C are sucrose-gelatin agar and Albimi broth with 10 % glycerin. Demonstrated is the fact that it is more efficient to conserve microorganisms stored in working collections by way of deep freezing
Normal subgroups in the Cremona group (long version)
Let k be an algebraically closed field. We show that the Cremona group of all
birational transformations of the projective plane P^2 over k is not a simple
group. The strategy makes use of hyperbolic geometry, geometric group theory,
and algebraic geometry to produce elements in the Cremona group that generate
non trivial normal subgroups.Comment: With an appendix by Yves de Cornulier. Numerous but minors
corrections were made, regarding proofs, references and terminology. This
long version contains detailled proofs of several technical lemmas about
hyperbolic space
Hydrazides of glycine-containing decasubstituted pillar[5]arenes: Synthesis and encapsulation of Floxuridine
© 2018 Elsevier Ltd Hydrazides of glycine-containing decasubstituted pillar[5]arenes were synthesized and characterized. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that self-assembly into monodisperse spherical nanoparticles (28 nm) was typical in water for pillarene hydrazides containing glycylglycide fragments (1 × 10−3 M). Binding of the antitumor drug Floxuridine in water by the substituents of the macrocycle was established by NMR spectroscopy. It was shown by DLS and TEM, that heating the macrocycle-Floxuridine system in a 1:1 ratio at 1 × 10−4 M led to its self-organization into monodisperse spherical particles 132 nm in diameter
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