Self-Assembly of Polyhedral Hybrid Colloidal Particles

We have developed a new method to produce hybrid particles with polyhedral shapes in very high yield (liter quantities at up to 70% purity) using a combination of emulsion polymerization and inorganic surface chemistry. The procedure has been generalized to create complex geometries, including hybrid line segments, triangles, tetrahedra, octahedra, and more. The optical properties of these particles are tailored for studying their dynamics and self-assembly. For example, we produce systems that consist of index-matched spheres allowing us to define the position of each elementary particle in three-dimensional space. We present some preliminary studies on the self-assembly of these complex shaped systems based on electron and optical microscopy.Engineering and Applied SciencesPhysic

Regulatory T-cells in chronic lymphocytic leukemia: actor or innocent bystander?

Abstract: Regulatory T (Treg) cells are now under extensive investigation in chronic lymphocytic leukemia (CLL). This small subset of T-cells has been, in fact, considered to be involved in the pathogenesis and progression of CLL. However, whether Treg dysregulation in CLL plays a key role or it rather represents a simple epiphenomenon is still matter of debate. In the former case, Treg cells could be appealing for targeting therapies. Finally, Treg cells have also been proposed as a prognostic indicator of the disease clinical course

The DNA Damage Response Pathway Contributes to the Stability of Chromosome III Derivatives Lacking Efficient Replicators

In eukaryotic chromosomes, DNA replication initiates at multiple origins. Large inter-origin gaps arise when several adjacent origins fail to fire. Little is known about how cells cope with this situation. We created a derivative of Saccharomyces cerevisiae chromosome III lacking all efficient origins, the 5ORIΔ-ΔR fragment, as a model for chromosomes with large inter-origin gaps. We used this construct in a modified synthetic genetic array screen to identify genes whose products facilitate replication of long inter-origin gaps. Genes identified are enriched in components of the DNA damage and replication stress signaling pathways. Mrc1p is activated by replication stress and mediates transduction of the replication stress signal to downstream proteins; however, the response-defective mrc1AQ allele did not affect 5ORIΔ-ΔR fragment maintenance, indicating that this pathway does not contribute to its stability. Deletions of genes encoding the DNA-damage-specific mediator, Rad9p, and several components shared between the two signaling pathways preferentially destabilized the 5ORIΔ-ΔR fragment, implicating the DNA damage response pathway in its maintenance. We found unexpected differences between contributions of components of the DNA damage response pathway to maintenance of ORIΔ chromosome derivatives and their contributions to DNA repair. Of the effector kinases encoded by RAD53 and CHK1, Chk1p appears to be more important in wild-type cells for reducing chromosomal instability caused by origin depletion, while Rad53p becomes important in the absence of Chk1p. In contrast, RAD53 plays a more important role than CHK1 in cell survival and replication fork stability following treatment with DNA damaging agents and hydroxyurea. Maintenance of ORIΔ chromosomes does not depend on homologous recombination. These observations suggest that a DNA-damage-independent mechanism enhances ORIΔ chromosome stability. Thus, components of the DNA damage response pathway contribute to genome stability, not simply by detecting and responding to DNA template damage, but also by facilitating replication of large inter-origin gaps

Design and implementation of a fully transparent partial abort support for software transactional memory

Software transactional memory (STM) provides synchronization support to ensure atomicity and isolation when threads access shared data in concurrent applications. With STM, shared data accesses are encapsulated within transactions automatically handled by the STM layer. Hence, programmers are not requested to use code-synchronization mechanisms explicitly, like locking. In this article, we present our experience in designing and implementing a partial abort scheme for STM. The objective of our work is threefold: (1) enabling STM to undo only part of the transaction execution in the case of conflict, (2) designing a scheme that is fully transparent to programmers, thus also allowing to run existing STM applications without modifications, and (3) providing a scheme that can be easily integrated within existing STM runtime environments without altering their internal structure. The scheme we designed is based on automated software instrumentation, which injects into the application capabilities to undo the required portions of transaction executions. Further, it can correctly undo also non-transactional operations executed on the stack and the heap during a transaction. This capability allows programmers to write transactional code without concerns about the side effects of aborted transactions on both shared and thread-private data. We integrated and evaluated our partial abort scheme within the TinySTM open-source library. We analyze the experimental results we achieved with common STM benchmark applications, focusing on the advantages and disadvantages of the proposed solutions for implementing our scheme's different components. Hence, we highlight the appropriate choices and possible solutions to improve partial abort schemes further

Effective Runtime Management of Tasks and Priorities in GNU OpenMP Applications

OpenMP has become a reference standard for the design of parallel applications. This standard is evolving very fast, thus offering ever new opportunities to the application programmers. However, OpenMP runtime environments are often not fully aligned to the actual requirements imposed by the evolution of such standard. Among the main lacks, we find: (a) a limited capability to effectively cope with task priorities, and (b) the inadequacy in guaranteeing core properties while processing tasks such as the so called extit{work-conservativeness}---the ability of the OpenMP runtime environment to fully exploit the underlying multi-processor/multi-core machine through the avoidance of thread-blocking phases. In this article we present the design of extensions to the GNU OpenMP ({ t GOMP}) implementation, integrated into { t gcc}, which allow the effective management of tasks and their priorities. Our proposal is based on a user-space library---modularly combined with the one already offered by { t GOMP}---and an external kernel-level Linux module---offering the opportunity to exploit raising hardware facilities for the purpose of task/priority management. We also provide experimental results showing the effectiveness of our proposal, achieved by running either OpenMP common benchmarks or a new benchmark application (named {sc Hashtag-Text}) that we explicitly devised in order to stress the OpenMP runtime environment in relation to the above-mentioned task/priority management aspects

Osservambiente - a project for territorial governance

Osservambiente is an innovative project aiming at developing an information system for territorial governance. This system supports monitoring activities of several territorial and environmental elements. Also, by means of integrated tools it is possible to define the needs of data collection, to plan the required missions, and to manage various kinds of spatial-temporal correlated data. Data are geolocated (for both position and orientation), and can be collected by means of vehicles equipped with suitable data capture devices, which (periodically) follow precalculated routes to cover all orparts of the monitored area. The system provides desktop and web applications to manage captured data through virtual and cartographic navigation techniques. Theproject is funded by Regione Campania and developed in cooperation with Nergal s.r.l

Adaptive Model-based Scheduling in Software Transactional Memory

Software Transactional Memory (STM) stands as powerful concurrent programming paradigm, enabling atomicity and isolation while accessing shared data. On the downside, STM may suffer from performance degradation due to excessive conflicts among concurrent transactions, which cause waste of CPU-cycles and energy because of transaction aborts. An approach to cope with this issue consists of putting in place smart scheduling strategies which temporarily suspend the execution of some transaction in order to reduce the transaction conflict rate. In this article, we present an adaptive model-based transaction scheduling technique relying on a Markov Chain-based performance model of STM systems. Our scheduling technique is adaptive in a twofold sense: (i) it controls the execution of transactions depending on throughput predictions by the model as a function of the current system state, (ii) it re-tunes on-line the Markov Chain-based model to adapt it-and the outcoming transaction scheduling decisions-to dynamic variations of the workload. We have been able to achieve the latter target thanks to the fact that our performance model is extremely lightweight. In fact, to be recomputed, it requires a reduced set of input parameters, whose values can be estimated via a few on-line samples related to the current workload dynamics. We also present a scheduler that implements our adaptive technique, which we integrated within the open source TinySTM package. Further, we report the results of an experimental study based on the STAMP benchmark suite, which has been aimed at assessing both the accuracy of our performance model in predicting the actual system throughput and the advantages of the adaptive scheduling policy over literature techniques