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View original: http://arxiv.org/abs/1209.0766
We highlight the impact of cluster-mass-dependent evolutionary rates upon the evolution of the cluster mass function during violent relaxation, that is, while clusters dynamically respond to the expulsion of their residual star-forming gas. Mass-dependent evolutionary rates arise when the mean volume density of cluster-forming regions is mass-dependent. In that case, even if the initial conditions are such that the cluster mass function at the end of violent relaxation has the same shape as the embedded-cluster mass function (i.e. infant weight-loss is mass-independent), the shape of the cluster mass function does change transiently {\it during} violent relaxation. In contrast, for cluster-forming regions of constant mean volume density, the cluster mass function shape is preserved all through violent relaxation since all clusters then evolve at the same mass-independent rate. On the scale of individual clusters, we model the evolution of the ratio between the dynamical mass and luminous mass of a cluster after gas expulsion. Specifically, we map the radial dependence of the time-scale for a star cluster to return to equilibrium. We stress that fields-of-view a few pc in size only, typical of compact clusters with rapid evolutionary rates, are likely to reveal cluster regions which have returned to equilibrium even if the cluster experienced a major gas expulsion episode a few Myr earlier. We provide models with the aperture and time expressed in units of the initial half-mass radius and initial crossing-time, respectively, so that our results can be applied to clusters with initial densities, sizes, and apertures different from ours.
View original: http://arxiv.org/abs/1209.0865
Generally, there are two distinct effects in modifying the properties of low-dimensional nanostructures: surface effect (SS) due to increased surface-volume ratio and quantum size effect (QSE) due to quantum confinement in reduced dimension. The SS has been widely shown to affect the elastic constants and mechanical properties of nanostructures. Here, using Pb nanofilm and graphene nanoribbon as model systems, we demonstrate the QSE on the elastic constants of nanostructures by first-principles calculations. We show that generally QSE is dominant in affecting the elastic constants of metallic nanostructures while SS is more pronounced in semiconductor and insulator nanostructures. Our findings have broad implications in quantum aspects of nanomechanics.
Aug 31, 2012 PembeRehber
Sonbahar geliyor… Ama biz tatil planlarımızı Eylül ayı üzerine yaptık. Yurt içi ve yurt dışı gezeceğiz biraz. Bilgisayarımı yanıma almayacağım. Artık neredeyse onunla yatıp kalktığım izin biraz özleyeyim dedim 
Klasik kremalı patatesi, biraz dağ kekiği, karabiber ve bol mısır ile lezzetlendirdim. İnce bir katman halinde cam kaba dizdim ve fırınladım. Leziz mi leziz oldu…
Malzemeler:
- 2 adet patates (mandolin rende ile ince ince dilimlenmiş)
- 1 paket krema (200 mlt)
- 1 tatlı kaşığı tuz
- 1 su bardağı donmuş mısır
- Az karabiber
- Bir tutam dağ kekiği
Yapılışı:
1- Patateslerin kabukların soyup, ince ince dilimleyin (ben mandolin rende kullandım).
2- Derin bir kapta aldığınız patates dilimlerinin üzerine krema, tuz, baharatlar ve mısırı koyun karıştırın.
3- 30 cm lik bir cam kaba, ince bir katman halinde yaydığınız malzemeyi 190 dereceye ayarlanmış fırında 30-40 dk. pişirin.
Afiyet olsun.
