نتایج جستجو برای: primordial nature
تعداد نتایج: 326570 فیلتر نتایج به سال:
Observational constraints on the primordial lithium abundance are important for the evaluation of the baryonic density of the universe. Its precise determination however suffers from uncertainties due to the possible depletion of this element inside the stars. Here we present and discuss new results on the lithium abundances in Pop II stars obtained with most recent stellar models including the...
Observational Cosmology has indeed made very rapid progress in recent years. The ability to quantify the universe has largely improved due to observational constraints coming from structure formation Measurements of CMB anisotropy and, more recently, polarization have played a very important role. Besides precise determination of various parameters of the ‘standard’ cosmological model, observat...
The idea that dark matter in the form of small compact bodies (most plausibly planetary mass primordial black holes) betrays its presence by the microlensing of quasars, has been stimulated by statistical studies of quasar light curves and gravitationally lensed quasar systems. In this paper we review this evidence, and discuss the significance of the recent detection of a planetary mass microl...
The simplest models of inflation based on slow roll produce nearly scale invariant primordial power spectra (PPS). But there are also numerous models that predict radically broken scale invariant PPS. In particular, markedly cuspy dips in the PPS correspond to nulls where the perturbation amplitude, hence PPS, goes through a zero at a specific wavenumber. Near this wavenumber, the true quantum ...
Background: With all the recent advances in cancer treatments, many young cancer patients find themselves facing the prospect of losing their fertility after aggressive chemotherapy or radiotherapy. Cryopreservation of ovarian cortical tissue has emerged as a potential option to restore fertility in these young women. Materials and Methods: Because autotransplantation of cryopreserved ovarian c...
Coal, like most materials found in nature, contain trace quantities of the naturally occurring primordial radionuclides. Therefore, the combustion of coals results in the release into the environment of some natural radioactive elements and in a redistribution of these radioactive elements in the surface soil particularly in the vicinity of coal-fired power plants, where it can modify ambient r...
Precision measurements of anisotropies in the cosmic microwave background and of the clustering of largescale structure have supposedly confirmed that the primordial density perturbation has a (nearly) scale-invariant spectrum. However this conclusion is based on assumptions about the world model and the nature of the dark matter. Physical models of inflation suggest that the spectrum may not i...
Since time began, humanity has sought to manipulate their environment to minimize the impact of the unpleasant forces of nature upon the frailty of the human body. It began with primordial man learning inductively through discovery rather than applying known laws or theorems. Today the inductive process is largely lost in the field of electronics where complete circuits are provided in school l...
The assembly of the developmentally arrested primordial follicle and the subsequent transition of the primordial follicle to the primary follicle are critical processes in normal ovarian physiology that remain to be elucidated. Ovarian follicles do not proliferate and the primordial follicles present in the neonate represent the total number of gametes available to a female throughout her repro...
We consider the hypothesis of the primordial nature of the non-enzymatic reverse tricarboxylic acid (rTCA) cycle and describe a modeling approach to quantify the uncertainty of this hypothesis due to the combinatorial aspect of the constituent chemical transformations. Our results suggest that a) rTCA cycle belongs to a degenerate optimum of auto-catalytic cycles, and b) the set of targets for ...
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