Negative potentials and collapsing universes

Hidden negative energies in strongly accelerated universes

where u is the velocity of an observer while "u is the energy density and P is the pressure measured by the observer and we use the (þ ) convention for the metric. The equation-of-state parameter is then defined as w P="u. In cosmological setups, one then considers homogeneous and isotropic Friedmann universes. In such a case, even for more general, imperfect-fluid DE models, the configuration ...

Cosmology With Negative Potentials

We investigate cosmological evolution in models where the effective potential V (φ) may become negative for some values of the field φ. Phase portraits of such theories in space of variables (φ, φ̇,H) have several qualitatively new features as compared with phase portraits in the theories with V (φ) > 0. Cosmological evolution in models with potentials with a “stable” minimum at V (φ) < 0 is sim...

diagnostic and developmental potentials of dynamic assessment for writing skill

این پایان نامه بدنبال بررسی کاربرد ارزیابی مستمر در یک محیط یادگیری زبان دوم از طریق طرح چهار سوال تحقیق زیر بود: (1) درک توانایی های فراگیران زمانیکه که از طریق برآورد عملکرد مستقل آنها امکان پذیر نباشد اما در طول جلسات ارزیابی مستمر مشخص شوند; (2) امکان تقویت توانایی های فراگیران از طریق ارزیابی مستمر; (3) سودمندی ارزیابی مستمر در هدایت آموزش فردی به سمتی که به منطقه ی تقریبی رشد افراد حساس ا...

Setoids and universes

Setoids commonly take the place of sets when formalising mathematics inside type theory. In this note, the category of setoids is studied in type theory with as small universes as possible (and thus, the type theory as weak as possible). Particularly, we will consider epimorphisms and disjoint sums. It is shown that, given the minimal type universe, all epimorphisms are surjections, and disjoin...

Cognition and event-related potentials. I. The relation of negative potentials and cognitive processes.