University of Ljubljana

About: University of Ljubljana is a education organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 17210 authors who have published 47013 publications receiving 1082684 citations. The organization is also known as: Univerza v Ljubljani.

Eigenvalues, diameter, and mean distance in graphs

Abstract: It is well-known that the second smallest eigenvalue? 2 of the difference Laplacian matrix of a graphG is related to the expansion properties ofG. A more detailed analysis of this relation is given. Upper and lower bounds on the diameter and the mean distance inG in terms of? 2 are derived.

A survey of processors with explicit multithreading

Abstract: Hardware multithreading is becoming a generally applied technique in the next generation of microprocessors. Several multithreaded processors are announced by industry or already into production in the areas of high-performance microprocessors, media, and network processors.A multithreaded processor is able to pursue two or more threads of control in parallel within the processor pipeline. The contexts of two or more threads of control are often stored in separate on-chip register sets. Unused instruction slots, which arise from latencies during the pipelined execution of single-threaded programs by a contemporary microprocessor, are filled by instructions of other threads within a multithreaded processor. The execution units are multiplexed between the thread contexts that are loaded in the register sets.Underutilization of a superscalar processor due to missing instruction-level parallelism can be overcome by simultaneous multithreading, where a processor can issue multiple instructions from multiple threads each cycle. Simultaneous multithreaded processors combine the multithreading technique with a wide-issue superscalar processor to utilize a larger part of the issue bandwidth by issuing instructions from different threads simultaneously.Explicit multithreaded processors are multithreaded processors that apply processes or operating system threads in their hardware thread slots. These processors optimize the throughput of multiprogramming workloads rather than single-thread performance. We distinguish these processors from implicit multithreaded processors that utilize thread-level speculation by speculatively executing compiler- or machine-generated threads of control that are part of a single sequential program.This survey paper explains and classifies the explicit multithreading techniques in research and in commercial microprocessors.

Forest microclimate dynamics drive plant responses to warming

Abstract: Climate warming is causing a shift in biological communities in favor of warm-affinity species (i.e., thermophilization). Species responses often lag behind climate warming, but the reasons for such lags remain largely unknown. Here, we analyzed multidecadal understory microclimate dynamics in European forests and show that thermophilization and the climatic lag in forest plant communities are primarily controlled by microclimate. Increasing tree canopy cover reduces warming rates inside forests, but loss of canopy cover leads to increased local heat that exacerbates the disequilibrium between community responses and climate change. Reciprocal effects between plants and microclimates are key to understanding the response of forest biodiversity and functioning to climate and land-use changes.

Tissue engineered bone grafts: biological requirements, tissue culture and clinical relevance.

Abstract: The tremendous need for bone tissue in numerous clinical situations and the limited availability of suitable bone grafts are driving the development of tissue engineering approaches to bone repair. In order to engineer viable bone grafts, one needs to understand the mechanisms of native bone development and fracture healing, as these processes should ideally guide the selection of optimal conditions for tissue culture and implantation. Engineered bone grafts have been shown to have capacity for osteogenesis, osteoconduction, osteoinduction and osteointegration - functional connection between the host bone and the graft. Cells from various anatomical sources in conjunction with scaffolds and osteogenic factors have been shown to form bone tissue in vitro. The use of bioreactor systems to culture cells on scaffolds before implantation further improved the quality of the resulting bone grafts. Animal studies confirmed the capability of engineered grafts to form bone and integrate with the host tissues. However, the vascularization of bone remains one of the hurdles that need to be overcome if clinically sized, fully viable bone grafts are to be engineered and implanted. We discuss here the biological guidelines for tissue engineering of bone, the bioreactor cultivation of human mesenchymal stem cells on three-dimensional scaffolds, and the need for vascularization and functional integration of bone grafts following implantation.