719 research outputs found
Contemporary landscape and the archaeological record. An integrated approach to the study of the Etruscan-Samnite site of Pontecagnano (SA)
Pontecagnano is a large Etruscan-Samnite settlement located 8 km SE of Salerno, at the northern edge of the Sele plain. The well-investigated necropolis provided data that made it possible to analyse the structure of the ancient community and reconstruct its long-term development. Over the last few years, after archaeological investigations carried out during roadwork to widen the Salerno-Reggio Calabria highway, a more systematic study of the site was begun. The analysis of archaeological data was combined with environmental and landscape studies, shedding light on the reasons behind the spatial organisation of the settlement, which was influenced by natural or man-made landscape elements such as streams, non-uniform dislocation of geological formations, terraces, roads, canals, etc. The aim of this paper is to illustrate the methods and instruments we used to develop a system that can dynamically combine archaeological and geomorphological data. The paper focuses particularly on the reconstruction of paleo-topographical areas of the ancient settlement. Our investigation outlined the physical and environmental limits within which the old town developed, especially as regards the archaic and classical period. Part of the work was devoted to reconstructing in detail the connections between the modern and the ancient landscape, not only by reading and interpreting the aerial photographs from 1945 to the present-day, but also by analyzing the evidence from the excavations. This approach allowed us to draw up a detailed geomorphologic map of the area of the ancient settlement - part of the GIS platform - and develop a three-dimensional model of the ground (DEM)
Planning and management of actions on transportation system to address extraordinary events in post-emergency situations. A multidisciplinary approach
The main aim of the work is the design and implementation of an integrated procedure for the identification of optimum action plans (satisfying expenditure constraints) on a road transportation system to minimize the impact produced on it by extraordinary events, in particular earthquakes. The attention is focused particularly on post-emergency situations related to effects on transportation networks caused by extraordinary events; the effects are considered with reference to bridges. Addressing the transition from physical effects to functional effects (relating to mobility) on the single infrastructure element calls for a commitment which has appeared challenging in view of the strongly innovative content involved. The analysis process consists in different steps. At the first step an effort must be made in order to acquire knowledge about the characteristics of the set of infrastructures (bridges) and about a set of possible seismic scenarios. By using fragility curves of bridges, the damage state of the network links (in which bridges are included) can be obtained. By making a series of hypotheses on how a bridge damage state can influence linksâ functionality, a set of âdamagedâ (lower capacity) road network models has been carried out. At the next step of the process, interaction between transportation supply and demand, by way of static or dynamic traffic assignment models, allows to measure the performance of the system, or rather, its overall response to extraordinary events using suitable performance indexes. Then, the network risk curve (probability of the seismic action vs. transportation system performance indexes) is derived. At the end of the process a cost-effective retrofit strategy has been identified. The procedure has been applied to a test network at regional scale in the north-east of Italy
Anterolateral Ligament of the Knee: Back to the Future in Anterior Cruciate Ligament Reconstruction
Although the importance of the anterolateral stabilizing structures of the knee in the setting of anterior cruciate ligament (ACL) injuries has been recognized since many years, most of orthopedic surgeons do not take into consideration the anterolateral structures when performing an ACL reconstruction. Anatomic single or double bundle ACL reconstruction will improve knee stability, but a small subset of patients may experience some residual anteroposterior and rotational instability. For this reason, some researchers have turned again towards the anterolateral aspect of the knee and specifically the anterolateral ligament. The goal of this review is to summarize the existing knowledge regarding the anterolateral ligament of the knee, including anatomy, histology, biomechanics and imaging. In addition, the most common anterolateral reconstruction/tenodesis techniques are described together with their respective clinical outcomes
Meniscal root tear repair: why, when and how?
The integrity of the meniscal root insertions is fundamental to preserve correct knee kinematics and avoid degenerative changes of the knee. Injuries to the meniscal attachments can lead to meniscal extrusion, decreased contact surface, increased cartilage stress, and ultimately articular degeneration. Recent and well designed studies have clarified the anatomy and biomechanics of the medial and lateral meniscal roots. Although the treatment of meniscal root tears is still controversial, many different techniques have been described for root repair. The goal of this review is to summarize the existing knowledge regarding meniscal root tears, including anatomy, biomechanics and imaging. In addition, the most common surgical techniques, together with the clinical outcomes, are described
A surge of late-occurring meiotic double-strand breaks rescues synapsis abnormalities in spermatocytes of mice with hypomorphic expression of SPO11
Meiosis is the biological process that, after a cycle of DNA replication, halves the cellular chromosome complement, leading to the formation of haploid gametes. Haploidization is achieved via two successive rounds of chromosome segregation, meiosis I and II. In mammals, during prophase of meiosis I, homologous chromosomes align and synapse through a recombination-mediated mechanism initiated by the introduction of DNA double-strand breaks (DSBs) by the SPO11 protein. In male mice, if SPO11 expression and DSB number are reduced below heterozygosity levels, chromosome synapsis is delayed, chromosome tangles form at pachynema, and defective cells are eliminated by apoptosis at epithelial stage IV at a spermatogenesis-specific endpoint. Whether DSB levels produced in Spo11 +/â spermatocytes represent, or approximate, the threshold level required to guarantee successful homologous chromosome pairing is unknown. Using a mouse model that expresses Spo11 from a bacterial artificial chromosome, within a Spo11 â/â background, we demonstrate that when SPO11 expression is reduced and DSBs at zygonema are decreased (approximately 40 % below wild-type level), meiotic chromosome pairing is normal. Conversely, DMC1 foci number is increased at pachynema, suggesting that under these experimental conditions, DSBs are likely made with delayed kinetics at zygonema. In addition, we provide evidences that when zygotene-like cells receive enough DSBs before chromosome tangles develop, chromosome synapsis can be completed in most cells, preventing their apoptotic elimination
Stochastic Multi-Objective Evacuation Model Under Managed and Unmanaged policies
Abstract Natural and man-created disasters, such as hurricanes, earthquakes, tsunamis, accidents and terrorist attacks, require evacuation and assistance routes. Evacuation routes are mostly based on the capacities of the road network. However, in extreme cases, such as earthquakes, road network infrastructure may adversely be affected, and may not supply their required capacities. If for various situations, the potential damage for critical roads can be identified in advance, it is possible to develop an evacuation model, that can be used in various situations. This paper focuses on the development of a model for the design of an optimal evacuation network which simultaneously minimizes retrofit costs of critical links (bridges, tunnels, etc.) and evacuation time. The model considers infrastructures' vulnerability (as a stochastic function which is dependent on the event location and magnitude), road network, transportation demand and evacuation areas. Furthermore, the model evaluates the benefits of managed evacuation (system optimum) when compared to unmanaged evacuation (user equilibrium). The paper presents a mathematic model for the presented problem. However, since an optimal solution cannot be found within a reasonable timeframe, a heuristic model is presented as well. This heuristic model is based on evolutionary algorithms, which also provides a mechanism for solving the problem as a multi-objective stochastic problem. Using a real-world data, the algorithm is evaluated and compared to the unmanaged evacuation conditions. The results clearly demonstrate the advantages of managed evacuation, as the average travel time can be reduced by 5% to 30%
A nuclear factor 1 binding site mediates the transcriptional activation of a type I collagen promoter by transforming growth factor-beta
Transforming growth factor-beta (TGF-beta) increases the steady-state RNA levels of several fibroblast extracellular matrix proteins. Using DNA transfection, we show that TGF-beta stimulates the activity of the mouse alpha 2(l) collagen promoter 5- to 10-fold in mouse NIH 3T3 and rat osteosarcoma cells. Deletion analysis indicates that a segment of this promoter between -350 and -300, overlapping a nuclear factor 1 (NF1) binding site, is needed for TGF-beta stimulation. A 3 bp substitution mutation abolishing NF1 binding to this site inhibits TGF-beta activation. Insertion of this NF1 binding site 5' to the SV40 early promoter makes the promoter TGF-beta inducible, but the 3 bp substitution does not. Similarly, when the NF1 binding site at the replication origin of adenovirus 2 and 5 is inserted 5' to the SV40 promoter, the promoter responds to TGF-beta. Therefore an NF1 binding site mediates the transcriptional activation of the mouse alpha 2(l) collagen promoter by TGF-beta
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