فهرست مطالب

  • Volume:1 Issue:2, 2007
  • تاریخ انتشار: 1385/10/11
  • تعداد عناوین: 6
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  • Construction of some Join Spaces from Boolean Algebras
    Ali Reza Ashrafi Page 1
    The aim of this paper is to construct an algebraic hyperstructure over a set G corresponding to a Boolean algebra B and a function S:G® B. In order to accomplish this goal we will need to define a hyperoperation * s on the set G. We define, a* s b ={g ÎG s(g) £ s(a) Ú s(b)} and prove that if the image of G is a Ú-semilattice or constitute apartition of 1 in B, then (G, *s) is a hypergroup.
  • Deformational Behavior of Quartz and Feldspar in Quartzites within Shear Zones in the Adelaide Hills Area, South Australia
    Ali Yassaghi Page 2
    Observations on the deformational behavior of quartz and feldspargrains in the Stonyfell Quartzite within the shear zones in Adelaide Hills area show that quartz grains exhibit mainly intracrystalline deformation features while feldspar grains show mainly internalfracturing. In grains with greater dislocation density, however, quartz grains show evidence of dynamic recrystallisation and feldspar grains display only weak intracrystalline deformation features. From these observations it appears that strain and displacement along the shear zones was accommodated mainly by dislocation creep (crystal plastic)deformation mechanism. This can be constrain by the greater reduction in the lengths of short axes of quartz grains with respect to their long axes. Moreover, quantitative evaluation of the quartz-grain configuration data on a number of quartzite samples from within shear zones indicates that from the upper transitional zones toward the baseof shear zones the grain size decreases, the aspect ratio increases, and the shape-preferred orientation of grains is modified due to shearing process. Similarly, the intensity of intracrystalline deformation features in quartz grains increases from the upper transitional zones towards the base of shear zones. Along the base of shear zones, softening mechanisms reduced the work-hardening process and increased theductility of the quartzite which can be evidenced by the development of core and mantle structures
  • Theoretical and Experimental Investigation on Back-scattered Low Energy Gamma Radiation from Different Metals
    A.Pazirandeh, N.Sobhkhiz Page 3
    Gamma-ray and X-ray are powerful tools for analysis of internal material micro-structure. The technique is based on studying the leakage spectrum. Two basic phenomena are involved in this work, namely photo-electric effect and Compton scattering. We derived the fundamental equations to calculate four components contributed in building up the leakage spectrum, which are Compton-Compton, Rayleigh-Compton, Compton-Rayleigh and Rayleigh -Rayleigh scattering. Results of our calculation and measurements for aluminum target showed very good agreement.
  • Characterization of Certain Infinitely Divisible Distributions
    M. Hossein Alamatsaz Page 4
    The aim of this note is to characterize a class of distributions whose characteristic functions (t) for all a > 0 satisfy the relation [?•(t)]? ‡? •(?• t), H? ‡ H?‡? ‡t?•Rwhere H and H?‹are positive real constants. First, it is observed that these distributions turn out to belong to the well-known class of infinitely divisible distributions. More specifically, they are strictly stable and thus absolutely continuous, self-decomposable andunimodal. But they are not strongly unimodal except for the case of H=2H. Then some representations are obtained for? ž(t). Finally, some characterizations are arrived at for the Cauchy and N (0,? °2); 0
  • Occurrence and Distribution of Aquatic Saprolegniaceae in Northwest and South of Tehran
    T. Nejadsattari Page 5
    Twelve aquatic sites in northwest and south of Tehran were sampled at monthly intervals form June through February 1996–1997 for members of Saprolegniaceae. In this study 12 genera and species were isolated.Saprolegnia with five species and Achlya with two species were more common whereas, Isoachlya, Leptolegniella, Protoachlya and Pythiopsis all had low frequencies. Species of S.ferax was abundant in cool waters of winter and fall, whereas species of S.litolaris hadhighest frequency during summer months. Species of Achlya chlorata was more abundant during summer months. A.debaryana was isolated during summer and fall with almost the same frequency. Occurrence of species of this family was comparable withoccurrence of those in other temperate zones, although, there was some differences in comparison with findings of other workers
  • Effect of Pectic Acid and? l-Glucan on Prolactin Secretion by Ovine Pituitary Explants
    Houri Sepehri, Roya Zoraghi, Ali, Haeri Rouhani Page 6
    Recent studies have indicated that several plant extracts reputed to be lactogenic are capable of inducing -casein synthesis in mammary epithelial cells. This enhancement is mediated through a stimulation of prolactin release from lactotropes in anterior pituitary. Therefore it is admitted that these extracts are capable of stimulating prolactinsecretion from hypophysis. A partial purification of these extracts, revealed that their active compounds are pectin in most cases and - glucan in other cases. In this work, the effect of various concentrations of both pure pectic acid and -glucan on prolactin secretion from ewe hypophysis fragments is investigated. It is shown that pectic acid in the 50-150? (g/ml range concentration and -glucan in the 200-400? (g/mlrange concentration are capable of stimulating prolactin secretion significantly (P<0.05, P<0.01), from hypophysis explants