Standards für Trusted Clouds

Die aktuellen Entwicklungen von Cloud Services werden haupts?chlich von gro?en Unternehmen vorangetrieben, dies ist aus unterschiedlichen Gründen für das Vertrauen in die Cloud Computing nicht nur f?rderlich. Ein wichtiges Werkzeug für die Vertrauenswürdigkeit sind Standards. Doch in welchen Bereichen sind welche (neuen) Standards erforderlich? Der Artikel gibt einen ersten überblick.     

A New Public-Key Cryptosystem over a Quadratic Order with Quadratic Decryption Time

We present a new cryptosystem based on ideal arithmetic in quadratic orders. The method of our trapdoor is different from the Diffie—Hellman key distribution scheme or the RSA cryptosystem. The plaintext m is encrypted by mp ^r , where p is a fixed element and r is a random integer, so our proposed cryptosystem is a probabilistic encryption scheme and has the homomorphy property. The most prominent property of our cryptosystem is the cost of the decryption, which is of quadratic bit complexity in the length of the public key. Our implementation shows that it is comparably as fast as the encryption time of the RSA cryptosystem with e=2 ¹⁶ +1 . The security of our cryptosystem is closely related to factoring the discriminant of a quadratic order. When we choose appropriate sizes of the parameters, the currently known fast algorithms, for example, the elliptic curve method, the number field sieve, the Hafner—McCurley algorithm, are not applicable. We also discuss that the chosen ciphertext attack is not applicable to our cryptosystem. Received 29 June 1998 and revised 15 November 1998     

Electrical transport properties of hydrogen-exposed n-type InSb films

Hall coefficients and d.c. conductivities were measured for polycrystalline n-type InSb films exposed to H₂ gas at different pressures. It was found that H₂ gas molecules act as donor impurities for the films and the donor action increases with increasing pressure of the gas. The mobility, however, was found to decrease, showing the increasing contribution of ionized impurity scattering with increasing pressure of the gas.     

Electrical transport properties of heavily indium- doped polycrystalline CdS films

CdS was doped with up to 1.5 at.% In by means of a chemical method. Films were produced from the chemically prepared charge by evaporation onto glass. Measurements of the d.c. conductivity and the Hall effect were made on these films. It was observed that the carrier concentration in the films increases by two orders of magnitude on the addition of 1.0 at.% In. The carrier concentration remains almost constant, however, on further addition of indium. In contrast, the mobility increases on the addition of indium up to 1.0 at.% but it decreases when further indium is added.     

Electrokinetics in nanochannels grafted with poly-zwitterionic brushes

In this paper, we compute the electrokinetic transport in soft nanochannels grafted with poly-zwitterionic (PZI) brushes. The transport is induced by an external pressure gradient, which drives the ionic cloud (in the form of an electric double layer or EDL) at the brush surfaces to induce an electric field that drives an induced electroosmotic transport. We characterize the overall transport by quantifying this electric field, overall flow velocity, and the energy conversion associated with the development of the electric field and a streaming current. We specially focus on how the ability of the PZI to ionize and demonstrate a significant charge at both large and small pH can be efficiently maneuvered to develop a liquid transport, an electric field, and an electrokinetically induced power across a wide range of pH values.     

Enterolithiasis, refractory anemia, and strictures of Crohn''s disease

It has been recently shown that NGF is not only involved in the survival and development of sympathetic and neural crest-derived sensory neurons, but also in some mechanisms of the immune system. For this reason, we studied the content of NGF in CSF samples from patients with diseases in which neuroimmunological mechanisms seem to be involved (multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer disease, chronic relapsing polyradiculoneuritis, Guillain-Barré syndrome, and tumors of the nervous system), as well as from a number of normal control subjects. We setup an ELISA aimed at the beta subunit of NGF, obtaining good validation tests and a detection limit of 28 pg beta NGF per ml. None of the samples was found to contain detectable levels of NGF and, when a concentration method for sample enrichment was used, only one patient was NGF-positive. This suggests that NGF is probably not involved in the neuroimmunological mechanisms underlying some inflammatory and degenerative diseases of the nervous system.     

3D self-assembled plasmonic superstructures of gold nanospheres: synthesis and characterization at the single-particle level

The synthesis of 3D self-assembled plasmonic superstructures of gold nanospheres as well as the characterization of their structural and optical properties at the single-particle level is presented. This experimental work is complemented by FEM (finite element method) simulations of elastic scattering spectra and the spatial |E|(4) distribution for establishing structure-activity correlations in these complex 3D nanoclusters.