315 research outputs found
Sediment transport at river contractions
No full textRiver contractions might occur because of either natural controls or hydraulic works. This paper aims to provide new insights on the temporal evolution of the morphological patterns at river contractions based on experiments at laboratory scale. Laboratory tests were performed in a 20 m long straight channel having a rectangular cross section, 1.0 m wide and 1.0 m deep. The erodible bed reach was made by almost uniform sediment consisting of either rough sand or medium gravel. The contraction model was 0.5,1.0, 2.0, or 3.0 m long. Three contraction ratios β=b/B=0.9, 0.8, and 0.7 were considered, with b width of the contracted reach and B width of the approach channel. The experiments were performed in clear-water scour regime and steady flow conditions. Typically, they were of long duration (up to 15 days) to achieve conditions of dynamic equilibrium, but runs of short duration were also carried out to acquire suitable experimental data at the earlier stages of the bed forms development. Compared to previous studies by the author on the same topic, new results are provided on bed morphology characteristics, also considering literature data, and predictive models on the time-dependent development of the bed degradation in and downstream of the contracted area
Le origini di Monte Oliveto nella storiografia: dalle Cronache Quattrocentesche alle recenti ricerche
No full textIL saggio esamina l'apporto che i cronisti medievali e della prima età moderna hanno fornito in rapporto alle origini della Congregazione di Monte Oliveto. Importante il confronto con gli studi del Novecento, che hanno ricostruito in modo filologico i testi medievali
eIF6
No full textGenetic and biochemical studies demonstrate that eIF6 controls the availability of 60S ribosomal subunits and does it in two ways. First, it regulates the biogenesis of 60S in the nucleolus through an unknown mechanism. Second, it prevents improper binding of free 60S to 40S subunits in the cytoplasm, keeping them available for translation. Total loss of eIF6 is lethal due to loss of 60S biogenesis. Fifty percent reduction of eIF6 results in impairment of growth factor-induced translation, and is accompanied by increased survival in tumor models. It is becoming increasingly clear that eIF6 levels and activity are rate-liming for tumor growth in various models. However, our understanding of the connection between eIF6 and tumorigenesis is still in its infancy. Uncovering oncogenic pathways regulating eIF6 and its downstream targets will provide further clues as to the likely role of this protein in cancer biology
Role of microRNAs in translation regulation and cancer
No full textMicroRNAs (miRNAs) are pervasively expressed and regulate most biological functions. They function by modulating transcriptional and translational programs and therefore they orchestrate both physiological and pathological processes, such as development, cell differentiation, proliferation, apoptosis and tumor growth. miRNAs work as small guide molecules in RNA silencing, by negatively regulating the expression of several genes both at mRNA and protein level, by degrading their mRNA target and/or by silencing translation. One of the most recent advances in the field is the comprehension of their role in oncogenesis. The number of miRNA genes is increasing and an alteration in the level of miRNAs is involved in the initiation, progression and metastases formation of several tumors. Some tumor types show a distinct miRNA signature that distinguishes them from normal tissues and from other cancer types. Genetic and biochemical evidence supports the essential role of miRNAs in tumor development. Although the abnormal expression of miRNAs in cancer cells is a widely accepted phenomenon, the cause of this dysregulation is still unknown. Here, we discuss the biogenesis of miRNAs, focusing on the mechanisms by which they regulate protein synthesis. In addition we debate on their role in cancer, highlighting their potential to become therapeutic targets
Bed morphology changes at river contractions
No full textContraction scour is a significant problem of engineering concern which might occur when the stream encounters a reduction in flow area because of either natural constraints or hydraulic works. This paper is a part of ongoing investigations by the authors on the spatial and temporal variations in bed morphology at both short and long river contractions based on experimental investigations at laboratory scale. Experiments were carried out at University of Basilicata, Italy, in a 1 m wide and 20 m long rectangular channel. The working section was up to 16 m, depending on the length of the contraction model. Two nearly-uniform sediments were used as mobile bed, sand with median grain size d50=1.7 mm and gravel with d50=9.0 mm. The contrac-tion length was either 0.5,1.0, 2.0 or 3.0 m. Runs were carried out under steady flow and clear-water approach flow conditions. Typically they were of long duration (up to 15 days) to achieve conditions of dynamic equi-librium. New results on the effects of contraction ratio, densimetric Froude number, and relative contraction length are given. Moreover, insights on the spatial and temporal changes in bed morphology are provided with emphasis on the thalweg profile at contracted sections and bed degradation processes downstream of the contracted area
Preliminary experiments on the evolution of river dunes
No full textDunes are common large-scale bedforms in sand-bed rivers that can affect significantly hydraulic roughness and water levels. This paper is a part of ongoing investigations by the authors on the evolution of river dunes. Here the spatial and temporal development of solitary sand dunes is investigated experimentally. Experiments were carried out at University of Basilicata, Italy, in a 1 m wide and 20 m long rectangular channel. A nearly-uniform sand with median grain size d50=1.7 mm was used as mobile bed. The working section was 16 m long. Each run was performed in two phases. Phase 1 aimed to generate the typical shape of the dune starting from an arc-shaped sand bar, of the same material as the mobile bed, set in a cross section perpendicular to the longitudinal channel axis. Phase 2 aimed to promote the downstream propagation of dunes generated in Phase 1 by either lowering the tailwater level or increasing the discharge. Based on the experimental data new insights are provided on the equilibrium morphology and the rate of migration of solitary sand dunes
The power of microRNA regulation-insights into immunity and metabolism
No full textMicroRNAs (miRNAs) are a prominent class of small non-coding RNAs that control gene expression. This comprehensive review explores the intricate roles of miRNAs in metabolism and immunity, as well as the emerging field of immunometabolism. The core of this work delves into the functional and regulatory capabilities of miRNAs, examining their complex influence on glucose and lipid metabolism, as well as their pivotal roles in shaping T-cell development and function. Specifically, this review addresses how miRNAs orchestrate the complex interaction between cellular metabolic processes and immune responses, underscoring the essential nature of these small regulatory molecules in maintaining homeostasis. Finally, we examine the emerging role of Artificial Intelligence (AI) in miRNA research, focusing on how machine learning techniques are revolutionizing the identification and validation of potential miRNA biomarkers. By integrating these diverse aspects, this review underscores the multifaceted roles of miRNAs in biological processes and their significant potential in advancing biomedical research and clinical applications
Parametri di qualità del suolo in un oliveto lavorato e in uno abbandonato
No full textL’abbandono degli oliveti è un fenomeno di rilevante importanza innescato essenzialmente da cause di natura economico-sociale. In un oliveto abbandonato gli alberi tendono a riassumere la loro originaria forma cespugliosa, le chiome diventano dense e compatte, la vegetazione spontanea colonizza gli spazi liberi secondo successioni ecologiche che conducono gradualmente, in tempi lunghissimi, verso una formazione naturale ove le componenti ‘suolo’ e ‘vegetazione’ sono in equilibrio. Tali agro-ecosistemi sono ormai molto rari. Con questa ricerca si è voluto indagare su alcuni parametri chimici e microbiologici del suolo di un oliveto pugliese abbandonato dal 1985 per definirne il livello di recupero della fertilità. Come riferimento è stato preso in considerazione un oliveto attiguo dalle stesse caratteristiche, condotto secondo le pratiche colturali tradizionalmente utilizzate nella zona. Campioni compositi di terreno sono stati prelevati a luglio 2010 dagli strati 0-20 e 20-40 cm. Il processo di recupero dei parametri di qualità nel suolo dell’oliveto abbandonato da 25 anni, innescato dall’assenza di gestione antropica, è apparso evidente. Esso ha presentato valori di C organico e N totale significativamente superiori a quelli dell’oliveto coltivato. Le conte microbiche hanno evidenziato un minor numero di batteri e funghi totali nel sistema non gestito. Le attività di alcuni degli enzimi coinvolti nel ciclo del carbonio (glicosidasi e cellulasi) sono risultate essere significativamente maggiori nel sistema non gestito, anche se l’alta attività della cellulasi non è stata accompagnata da un maggior numero di batteri cellulosolitici. Lo studio dei profili di utilizzazione dei substrati carboniosi (CLPP), mediante il metodo Biolog®, ha rilevato differenze significative fra i due oliveti per alcuni indici metabolici del microbiota del suolo. In generale, il sistema abbandonato ha mostrato una maggiore complessità e diversità microbica
Influence of cohesion on scour at piers founded in clay-sand-gravel mixtures
No full textAn accurate prediction of scour depth around bridge piers is crucial for economical and safe design of bridge pier foundations. The main objective of the present study is to identify the influencing cohesive parameters and their effects on the local scour processes around bridge piers, depending on various proportions of clay-sand-gravel mixtures. Twenty experimental tests were performed in a channel 25 m long and 1.0 m wide for this purpose. Runs lasted from 16 to 40 h. It was noted from the experimental work that an increment of clay fraction significantly reduces the scour depth around bridge piers. It was also observed that the initiation of scour occurred at the sides of the pier where separation of flow occurred. Typically, the maximum scour depth at the equilibrium stage was still observed at the sides of the pier. A dimensional analysis was used to propose mathematical relationships assessing the temporal scour depth variation at the wake and sides of the pier. The developed relationships yielded reasonable results with maximum error of two folds for 95.22% of total data sets for scour depth at the wake and 92.57% of the total data sets for scour depth at the sides of the pier
Improving IR-based Traceability Recovery via Noun-based Indexing of Software Artifacts
No full textOne of the most successful applications of textual analysis in software engineering is the use of information retrieval (IR) methods to reconstruct traceability links between software artifacts. Unfortunately, because of the limitations of both the humans developing artifacts and the IR techniques any IR-based traceability recovery method fails to retrieve some of the correct links, while on the other hand it also retrieves links that are not
correct. This limitation has posed challenges for researchers that have proposed several methods to improve the accuracy of IR-based traceability recovery methods by removing the ‘noise’ in the textual content of software artifacts (e.g., by removing common words or increasing the importance of critical terms). In this paper, we propose a heuristic to remove the ‘noise’ taking into account the linguistic nature of words in the software artifacts. In particular, the language used in software documents can be classified as a technical language, where the words that provide more indication on the semantics of a document are the nouns. The results of a case study conducted on five software artifact repositories indicate that characterizing the context
of software artifacts considering only nouns significantly improves the accuracy of IR-based traceability recovery methods
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