Effect of Osteoactivin and Bone Morphogenetic Protein-2 on soft tissue in Rat Spinal Fusion Model

Osteoinductive therapeutic strategies are essential for the bone healing process and are applicable in multiple orthopaedic procedures. The novel protein Osteoactivin (OA) has proven to stimulate osteoblast differentiation and function in vitro and bone regeneration in vivo in the rat model. More recently, OA has shown significant bone regeneration ability in sheep. The goal of this study is the comparison of osteoactivin with bone morphogenetic protein-2 (BMP-2) in the rat spinal fusion model

Solving frustration-free spin systems

We identify a large class of quantum many-body systems that can be solved exactly: natural frustration-free spin-1/2 nearest-neighbor Hamiltonians on arbitrary lattices. We show that the entire ground state manifold of such models can be found exactly by a tensor network of isometries acting on a space locally isomorphic to the symmetric subspace. Thus, for this wide class of models real-space renormalization can be made exact. Our findings also imply that every such frustration-free spin model satisfies an area law for the entanglement entropy of the ground state, establishing a novel large class of models for which an area law is known. Finally, we show that our approach gives rise to an ansatz class useful for the simulation of almost frustration-free models in a simple fashion, outperforming mean field theory.Comment: 5 pages, 1 figur

Efficient measurement-based quantum computing with continuous-variable systems

We present strictly efficient schemes for scalable measurement-based quantum computing using continuous-variable systems: These schemes are based on suitable non-Gaussian resource states, ones that can be prepared using interactions of light with matter systems or even purely optically. Merely Gaussian measurements such as optical homodyning as well as photon counting measurements are required, on individual sites. These schemes overcome limitations posed by Gaussian cluster states, which are known not to be universal for quantum computations of unbounded length, unless one is willing to scale the degree of squeezing with the total system size. We establish a framework derived from tensor networks and matrix product states with infinite physical dimension and finite auxiliary dimension general enough to provide a framework for such schemes. Since in the discussed schemes the logical encoding is finite-dimensional, tools of error correction are applicable. We also identify some further limitations for any continuous-variable computing scheme from which one can argue that no substantially easier ways of continuous-variable measurement-based computing than the presented one can exist.Comment: 13 pages, 3 figures, published versio

The allspice [Pimenta dioica (L.) Merrill, Myrtaceae] in the Sierra Norte de Puebla (México)

13 páginas, 9 figuras, 3 tablas.[ES] Pimenta dioica es una miliacea neotropical de distribución mesoamericana y caribeña. En México vive hacia el este y sudeste. Sus frutos secos se utilizan como condimento, y se trata de un producto del mercado nacional mexicano que también se exporta a Alemania, Estados Unidos, Jamaica y Reino Unido. Aunque la mayoría de la cosecha proviene de la recolección de los frutos en árboles silvestres del bosque tropical, últimamente se tiende a cultivar esta especie en un proceso actual de domesticación. Se exponen datos sobre propagación, domesticación, cosecha, procesado, mercado e importancia socioeconómica de la pimienta de Jamaica en la Sierra Norte de Puebla (México), a partir de los datos de campo obtenidos principalmente en una comunidad indígena totonaca, en donde se usa como medicinal, en alimentación y en tecnología. Además se reseña una obra de carácter histórico sobre la pimienta de Gómez Ortega, que ofrece datos históricos, botánicos, de cultivo y de comercio de esta especie.[EN] Pimenta dioica, allspice, is a neotropical Myrtaceae distributed in Mesoamerica and the Caribbean region. Its área of distribution in México ranges along East and Southeast parts of the country. The main use of its dried fruits is as spice, being sold in Mexican nacional markets as well as exported to Germany, the United States, Jamaica and Great Britain. Most of the harvest comes from trees growing wild in tropical forests, although lately there is a trend to domesticate and cultivate the plant. This paper describes the propagation, domestication, harvesting, processing, marketing and socioeconomic importance of allspice in the Sierra Norte de Puebla (México). The fieldwork has been focused on Totonaca indigenous communities from this area. In these communities, allspice has medicinal use, and is used as a condiment for food; other technological and cultural uses have been also recorded. A historical monograph from Casimiro Gómez Ortega is reviewed. It includes information of the history, botany, cultivation and commerce of allspice.Este estudio se realizó dentro del período de disfrute de una Beca Intercampus E.AL./96 núm. 0384 de la Agencia Española de Cooperación Internacional (AECI).Peer reviewe

Limitations of quantum computing with Gaussian cluster states

We discuss the potential and limitations of Gaussian cluster states for measurement-based quantum computing. Using a framework of Gaussian projected entangled pair states (GPEPS), we show that no matter what Gaussian local measurements are performed on systems distributed on a general graph, transport and processing of quantum information is not possible beyond a certain influence region, except for exponentially suppressed corrections. We also demonstrate that even under arbitrary non-Gaussian local measurements, slabs of Gaussian cluster states of a finite width cannot carry logical quantum information, even if sophisticated encodings of qubits in continuous-variable (CV) systems are allowed for. This is proven by suitably contracting tensor networks representing infinite-dimensional quantum systems. The result can be seen as sharpening the requirements for quantum error correction and fault tolerance for Gaussian cluster states, and points towards the necessity of non-Gaussian resource states for measurement-based quantum computing. The results can equally be viewed as referring to Gaussian quantum repeater networks.Comment: 13 pages, 7 figures, details of main argument extende

Fundamental and practical limits to image acceleration in parallel magnetic resonance imaging

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2005.Includes bibliographical references (leaves 152-160).Imaging speed in conventional magnetic resonance imaging (MRI) is limited by the performance of magnetic field gradients and the rate of power deposition in tissue. Parallel MRI techniques overcome these constraints by exploiting information stored within the spatial sensitivity patterns of radiofrequency detector arrays to substitute for some of the spatial information that would normally be obtained using magnetic field gradients. Parallel MRI strategies have been applied clinically to increase patient comfort, enhance spatial resolution, expand anatomical coverage, and reduce image artifacts. The effectiveness of parallel MRI techniques is largely determined by the amount of spatial information that is stored in the detector coil sensitivities. This dissertation investigates the spatial encoding properties of coil arrays from three practical and fundamental perspectives. First, a novel array design is presented that enables spatial encoding in multiple directions simultaneously. Second, the impact of inductive coupling between array elements in parallel MRI is investigated theoretically and experimentally. Finally, electromagnetic calculations are described that permit computation of the ultimate intrinsic signal-to-noise ratio available to any physically realizable coil array for parallel MR. These calculations help to establish fundamental limits to the image accelerations that may be achieved using parallel MRI techniques. These limits are intrinsically related to the wavelengths of the electromagnetic fields at MR imaging frequencies. The sensitivity patterns that correspond to the ultimate intrinsic SNR also represent potential starting points for new coil designs.by Michael A. Ohliger.Ph.D

Integration und Migration in Berlin

INTEGRATION UND MIGRATION IN BERLIN Integration und Migration in Berlin / Ohliger, Rainer (Rights reserved) ( -