Heteroepitaxy of deposited amorphous layer by pulsed electron-beam irradiation

We demonstrate that a single short pulse of electron irradiation of appropriate energy is capable of recrystallizing epitaxially an amorphous Ge layer deposited on either or Si single-crystal substrate. The primary defects observed in the case were dislocations, whereas stacking faults were observed in samples

Epitaxial growth of deposited amorphous layer by laser annealing

We demonstrate that a single short pulse of laser irradiation of appropriate energy is capable of recrystallizing in open air an amorphous Si layer deposited on a (100) single-crystal substrate into an epitaxial layer. The laser pulse annealing technique is shown to overcome the interfacial oxide obstacle which usually leads to polycrystalline formation in normal thermal annealing

Regulatory networks and connected components of the neutral space

The functioning of a living cell is largely determined by the structure of its regulatory network, comprising non-linear interactions between regulatory genes. An important factor for the stability and evolvability of such regulatory systems is neutrality - typically a large number of alternative network structures give rise to the necessary dynamics. Here we study the discretized regulatory dynamics of the yeast cell cycle [Li et al., PNAS, 2004] and the set of networks capable of reproducing it, which we call functional. Among these, the empirical yeast wildtype network is close to optimal with respect to sparse wiring. Under point mutations, which establish or delete single interactions, the neutral space of functional networks is fragmented into 4.7 * 10^8 components. One of the smaller ones contains the wildtype network. On average, functional networks reachable from the wildtype by mutations are sparser, have higher noise resilience and fewer fixed point attractors as compared with networks outside of this wildtype component.Comment: 6 pages, 5 figure

Gas chromatography mass spectrometry assay for ketamine and its metabolites in plasma

A highly sensitive and specific method for quantitation of ketamine and two of its metabolites found in monkey, dog and human plasma was developed using a gas chromatography selected ion monitoring assay operated in both electron impact and chemical ionization modes. This technique yields excellent precision, reproducibility and accuracy. From 1 ng to 3 μg of ketamine or its metabolites in 1 ml of plasma can be detected. The technique of electron capture gas chromatography is compared. All three assays were found to be quite useful but the gas chromatography mass spectrometry techniques were more specific.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144691/1/bms1200040508.pd

Frequency of oscillations of an error term related to the Euler function

Let φ be the Euler function, and consider the error term H in the asymptotic formul

Analytic structure of radiation boundary kernels for blackhole perturbations

Exact outer boundary conditions for gravitational perturbations of the Schwarzschild metric feature integral convolution between a time-domain boundary kernel and each radiative mode of the perturbation. For both axial (Regge-Wheeler) and polar (Zerilli) perturbations, we study the Laplace transform of such kernels as an analytic function of (dimensionless) Laplace frequency. We present numerical evidence indicating that each such frequency-domain boundary kernel admits a "sum-of-poles" representation. Our work has been inspired by Alpert, Greengard, and Hagstrom's analysis of nonreflecting boundary conditions for the ordinary scalar wave equation.Comment: revtex4, 14 pages, 12 figures, 3 table

Helical Tubes in Crowded Environments

When placed in a crowded environment, a semi-flexible tube is forced to fold so as to make a more compact shape. One compact shape that often arises in nature is the tight helix, especially when the tube thickness is of comparable size to the tube length. In this paper we use an excluded volume effect to model the effects of crowding. This gives us a measure of compactness for configurations of the tube, which we use to look at structures of the semi-flexible tube that minimize the excluded volume. We focus most of our attention on the helix and which helical geometries are most compact. We found that helices of specific pitch to radius ratio 2.512 to be optimally compact. This is the same geometry that minimizes the global curvature of the curve defining the tube. We further investigate the effects of adding a bending energy or multiple tubes to begin to explore the more complete space of possible geometries a tube could form.Comment: 10 page

Identifikasi Fitokimia Ekstrak Metanol Daun Paliasa (Melochiaumbellata (Houtt) Stapf) Dari Desa Renggarasi Dengan Metode Kromatografi Lapis Tipis (Klt)

Telah dilakukan penelitian mengenai Identifikasi fitokimia ekstrak metanol daun paliasa (Melochia umbellate (Houtt) stapf) dari Desa Renggarasi dengan Metode Kromatografi Lapis Tipis. Penelitian ini bertujuan untuk mengetahui senyawa sekunder yang terkandung pada daun paliasa melalui skrining fitokimia dan metode kromatografi lapis-tipis (KLT). Ekstraksi dilakukan menggunakan pelarut metanol 70% dengan cara maserasi, dan diperoleh rendemene kstrak sebanyak 0,057%. Pengujian kandungan metabolit sekunder pada ekstrak daun paliasa dilakukan secara skrining fitokimia. Hasil identifikasi positif diantaranya saponin, tanin, dan terpenoid. Selanjutnya dilakukan uji KLT dilakukan untuk melihat noda yang terbentuk pada daun paliasa dimana uji KLT ini untuk eleuen polar yaitu metanol : n-heksan (7:3) untuk noda 1 nilai Rf 0,02, noda 2 nilai Rf 0,04, noda 3 nilai Rf 0,06, dan noda 4 nilai Rf 0,1, untuk eluen non polar metanol: n-heksan (3:7) hanya terbentuk 1 noda dengan nilai Rf 0,06