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Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia characterized by an abnormal proliferation of promyelocytes. It is often associated with an aggressive clinical presentation involving complex coagulopathies including disseminated intravascular coagulation, with a significant risk of bleeding and/or thrombosis if treatment with all-trans-retinoic acid (ATRA) is not rapidly initiated. Here we present a unique case of APL which was isolated to femoral bone lesions, without definitive evidence of peripheral blood or bone marrow involvement, and without systemic sequelae.

IntroductionFluorescence in situ hybridization (FISH) is an essential ancillary study used to identify clinically aggressive subsets of large B-cell lymphomas that have MYC, BCL2, or BCL6 rearrangements. Small-volume biopsies such as fine needle aspiration biopsy (FNAB) and core needle biopsy (CNB) are increasingly used to diagnose lymphoma and obtain material for ancillary studies such as FISH. However, the performance of FISH in small biopsies has not been thoroughly evaluated or compared to surgical biopsies.MethodsWe describe the results of MYC, BCL2, and BCL6 FISH in a series of 222 biopsy specimens, including FNAB with cell blocks, CNBs, and surgical excisional or incisional biopsies from 208 unique patients aggregated from 6 academic medical centers. A subset of patients had FNAB followed by a surgical biopsy (either CNB or excisional biopsy) obtained from the same or contiguous anatomic site as part of the same clinical workup; FISH results were compared for these paired specimens.ResultsFISH had a low hybridization failure rate of around 1% across all specimen types. FISH identified concurrent MYC and BCL2 rearrangements in 20 of 197 (10%) specimens and concurrent MYC and BCL6 rearrangements in 3 of 182 (1.6%) specimens. The paired FNAB and surgical biopsy specimens did not show any discrepancies for MYC or BCL2 FISH; of the 17 patients with 34 paired cytology and surgical specimens, only 2 of the 49 FISH probes compared (4% of all comparisons) showed any discrepancy and both were at the BCL6 locus. One discrepancy was due to necrosis of the CNB specimen causing a false negative BCL6 FISH result when compared to the FNAB cell block that demonstrated a BCL6 rearrangement.DiscussionFISH showed a similar hybridization failure rate in all biopsy types. Ultimately, MYC, BCL2, or BCL6 FISH showed 96% concordance when compared across paired cytology and surgical specimens, suggesting FNAB with cell block is equivalent to other biopsy alternatives for evaluation of DLBCL or HGBCL FISH testing.

Whole slide imaging is revolutionizing the field of pathology and is currently being used for clinical, educational, and research initiatives by an increasing number of institutions. Pathology departments have distinct needs for digital pathology systems, yet the cost of digital workflows is cited as a major barrier for widespread adoption by many organizations. Memorial Sloan Kettering Cancer Center (MSK) is an early adopter of whole slide imaging with incremental investments in resources that started more than 15 years ago. This experience and the large-scale scan operations led to the identification of required framework components of digital pathology operations. The cost of these components for the 2021 digital pathology operations at MSK were studied and calculated to enable an understanding of the operation and benchmark the accompanying costs.This paper describes the unique infrastructure cost and the costs associated with the digital pathology clinical operation use cases in a large, tertiary cancer center. These calculations can serve as a blueprint for other institutions to provide the necessary concepts and offer insights towards the financial requirements for digital pathology adoption by other institutions.

The implementation of Digital Pathology has allowed the development of computational Pathology. Digital image-based applications that have received FDA Breakthrough Device Designation have been primarily focused on tissue specimens. The development of Artificial Intelligence-assisted algorithms using Cytology digital images has been much more limited due to technical challenges and a lack of optimized scanners for Cytology specimens. Despite the challenges in scanning whole slide images of cytology specimens, there have been many studies evaluating CP to create decision-support tools in Cytopathology. Among different Cytology specimens, thyroid fine needle aspiration biopsy (FNAB) specimens have one of the greatest potentials to benefit from machine learning algorithms (MLA) derived from digital images. Several authors have evaluated different machine learning algorithms focused on thyroid cytology in the past few years. The results are promising. The algorithms have mostly shown increased accuracy in the diagnosis and classification of thyroid cytology specimens. They have brought new insights and demonstrated the potential for improving future cytopathology workflow efficiency and accuracy. However, many issues still need to be addressed to further build on and improve current MLA models and their applications. To optimally train and validate MLA for thyroid cytology specimens, larger datasets obtained from multiple institutions are needed. MLAs hold great potential in improving thyroid cancer diagnostic speed and accuracy that will lead to improvements in patient management.

Introduction: For patients with advanced NSCLC, cytologic samples may be the only diagnostic specimen available for molecular profiling. Although both rapid and comprehensive assessment are essential in this setting, an integrated multitest approach remains an important strategy in many laboratories, despite the risks and challenges when working with scant samples. In this study, we describe our experience and high success rate in using a multitest approach, focusing on the clinical validation and incorporation of ultrarapid EGFR testing using the Idylla system followed by comprehensive next-generation sequencing (NGS). Methods: Cytology samples received for routine molecular testing were included in this study. The performance characteristics of the EGFR Idylla assay were assessed; tissue suitability parameters and interpretation criteria to supplement automated mutation calling were established. The assay performance was monitored for 1 year, comparing the results with those of concurrent NGS testing by MSK-IMPACT (primarily) or MSK-AmpliSeq and MSK-Fusion solid panel in a subset of cases. Results: Overall, 301 samples were studied; 83 samples were included in validation (60.2% [50 of 83] were positive for EGFR mutations). Concordance with the reference method was 96.4% (80 of 83) of the samples with excellent reproducibility. The limit of detection was variable depending on the total tissue input and the specific mutation tested. Unextracted tissue inputs that maintained total EGFR cycle of quantification at less than 23 allowed all mutations to be detected if present at greater than 5% variant allele frequency. Mutations could be detected at 1% variant allele frequency with total EGFR cycle of quantification of 18. During the clinical implementation phase, 218 NSCLC samples were tested by Idylla (24.3% [53 of 218] were EGFR mutation positive). Concurrent NGS testing was requested on 165 samples and successfully performed on 96.4% (159 of 165) of the samples. The Idylla automated results were concordant with those obtained by NGS in 96.2% (153 of 159) of cases and improved to 98.7% (157 of 159) after incorporation of manual review criteria to supplement automated calling, resulting in a diagnostic sensitivity of 95.6% (95% confidence interval: 84.9%–99.5%). In general, 9% (14 of 159) of the cases tested by NGS had EGFR mutations not covered by the Idylla assay, primarily insertions in exon 19 and 20 and minor mutations co-occurring with canonical sensitizing mutations. Conclusions: Comprehensive molecular testing is feasible and has a high success rate in NSCLC cytology samples when using a multitest approach. Testing with the Idylla system enables rapid and accurate determination of the EGFR status without compromising subsequent NGS testing.

Background: The first satellite center to offer interventional radiology procedures at Memorial Sloan Kettering Cancer Center opened in October 2014. Two of the procedures offered, fine needle aspirations and core biopsies, required rapid on-site cytologic evaluation of smears and biopsy touch imprints for cellular content and adequacy. The volume and frequency of such evaluations did not justify hiring on-site cytotechnologists, and therefore, a dynamic robotic telecytology (TC) solution was created. In this technical article, we present a detailed description of our implementation of robotic TC. Methods: Pathology devised the remote robotic TC solution after acknowledging that it would not be cost effective to staff cytotechnologists on-site at the satellite location. Sakura VisionTek was selected as our robotic TC solution. In addition to configuration of the dynamic robotic TC solution, pathology realized integrating the technology solution into operations would require a multidisciplinary effort and reevaluation of existing staffing and workflows. Results: Extensively described are the architectural framework and multidisciplinary process re-design, created to navigate the constraints of our technical, cultural, and organizational environment. Also reviewed are the benefits and challenges associated with available desktop sharing solutions, particularly accounting for information security concerns. Conclusions: Dynamic robotic TC is effective for immediate evaluations performed without on-site cytotechnology staff. Our goal is providing an extensive perspective of the implementation process, particularly technical, cultural, and operational constraints. Through this perspective, our template can serve as an extensible blueprint for other centers interested in implementing robotic TC without on-site cytotechnologists.

Background: The first satellite center to offer interventional radiology procedures at Memorial Sloan Kettering Cancer Center opened in October 2014. Two of the procedures offered, fine needle aspirations and core biopsies, required a rapid on-site cytologic evaluation of smears and biopsy touch imprints for cellular content and adequacy. The volume and frequency of such evaluations did not justify hiring on-site cytotechnologists, and therefore, a dynamic robotic telecytology (TC) solution was created. In this article, we provide data on our experience with this active implementation. Sakura VisionTek was selected as our robotic TC solution. Methods: A retrospective analysis of all TC evaluations from this satellite site was performed. Information was collected on demographics, lesion location, imaging modality; a comparison of TC-assisted adequacy with final adequacy was also conducted. Results: An analysis of 439 cases was performed over a period of 23 months with perfect correlation in 92.7% (407/439) of the cases. An adequacy upgrade (inadequate specimen becomes adequate) in 6.6% (29/439) of the cases. An adequacy downgrade (adequate specimen becomes inadequate), is near zero at 0.7% (3/439) of the cases. Conclusions: Dynamic robotic TC is effective for immediate evaluations performed without on-site cytotechnology staff. The overall intent of this article is to present data and concordance rates as outcome metrics. Thus far, such outcome metrics have exceeded our expectations. Our TC implementation shows high, perfect concordance. Adequacy upgrades are minor but more relevant and impressive is a near zero adequacy downgrade. Our full implementation has been so successful that plans are in place for configurations at future satellite sites.

Background: The use of minimally invasive procedures to obtain material for diagnostic purposes has become more prevalent in recent years. As such, there is increased demand for immediate cytologic adequacy assessment of minimally invasive procedures. The array of different locations in which rapid on-site evaluation (ROSE) is expected requires an ever-increasing number of cytology personnel to provide support for adequacy assessment. In our study, we describe the implementation process of a telecytology (TC) system in a high case volume setting and evaluate the performance of this activity. Methods: We performed retrospectively an analysis of all consecutive remote TC ROSE evaluations obtained for 15 months. The specimens were evaluated using a TC system. The ROSE adequacy assessment obtained at the time of the procedure was compared to the final cytopathologist-rendered adequacy assessment when all the material was available for review, including the alcohol-fixed preparations. Results: A total of 8106 distinct cases were analyzed. TC-assisted preliminary adequacy assessment was highly concordant with the final cytopathologist-rendered adequacy assessment. Perfect concordance or accuracy was at 93.1% (7547/8106). The adequacy upgrade rate (inadequate specimen became adequate) was 6.8% (551/8106), and the initial adequacy downgrade (adequate specimen became inadequate) was

BackgroundThe high mortality rate associated with epithelial ovarian carcinoma (EOC) reflects diagnosis commonly at an advanced stage, but improved early detection is hindered by uncertainty as to the histologic origin and early natural history of this malignancy.Methodology/principal findingsHere we report combined molecular genetic and morphologic analyses of normal human ovarian tissues and early stage cancers, from both BRCA mutation carriers and the general population, indicating that EOCs frequently arise from dysplastic precursor lesions within epithelial inclusion cysts. In pathologically normal ovaries, molecular evidence of oncogenic stress was observed specifically within epithelial inclusion cysts. To further explore potential very early events in ovarian tumorigenesis, ovarian tissues from women not known to be at high risk for ovarian cancer were subjected to laser catapult microdissection and gene expression profiling. These studies revealed a quasi-neoplastic expression signature in benign ovarian cystic inclusion epithelium compared to surface epithelium, specifically with respect to genes affecting signal transduction, cell cycle control, and mitotic spindle formation. Consistent with this gene expression profile, a significantly higher cell proliferation index (increased cell proliferation and decreased apoptosis) was observed in histopathologically normal ovarian cystic compared to surface epithelium. Furthermore, aneuploidy was frequently identified in normal ovarian cystic epithelium but not in surface epithelium.Conclusions/significanceTogether, these data indicate that EOC frequently arises in ovarian cystic inclusions, is preceded by an identifiable dysplastic precursor lesion, and that increased cell proliferation, decreased apoptosis, and aneuploidy are likely to represent very early aberrations in ovarian tumorigenesis.

Abstract Inferring causal relationships from observational data is a key challenge in understanding the interpretability of Machine Learning models. Given the ever-increasing amount of observational data available in many areas, Machine Learning algorithms used for forecasting have become more complex, leading to a less understandable path of how a decision is made by the model. To address this issue, we propose leveraging ensemble models, e.g., Random Forest, to assess which input features the trained model prioritizes when making a forecast and, in this way, establish causal relationships between the variables. The advantage of these algorithms lies in their ability to provide feature importance, which allows us to build the causal network. We present our methodology to estimate causality in time series from oil field production. As it is difficult to extract causal relations from a real field, we also included a synthetic oil production dataset and a weather dataset, which is also synthetic, to provide the ground truth. We aim to perform causal discovery, i.e., establish the existing connections between the variables in each dataset. Through an iterative process of improving the forecasting of a target’s value, we evaluate whether the forecasting improves by adding information from a new potential driver; if so, we state that the driver causally affects the target. On the oil field-related datasets, our causal analysis results agree with the interwell connections already confirmed by tracer information; whenever the tracer data are available, we used it as our ground truth. This consistency between both estimated and confirmed connections provides us the confidence about the effectiveness of our proposed methodology. To our knowledge, this is the first time causal analysis using solely production data is employed to discover interwell connections in an oil field dataset.

Extracellular synthesis of functional cyclodextrins (CDs) as intermediates of starch assimilation is a convenient microbial adaptation to sequester substrates, increase the half-life of the carbon source, carry bioactive compounds, and alleviate chemical toxicity through the formation of CD-guest complexes. Bacteria encoding the four steps of the carbohydrate metabolism pathway via cyclodextrins (CM-CD) actively internalize CDs across the microbial membrane via a putative type I ATP-dependent ABC sugar importer system, MdxEFG-(X/MsmX). While the first step of the CM-CD pathway encompasses extracellular starch-active cyclomaltodextrin glucanotransferases (CGTases) to synthesize linear dextrins and CDs, it is the ABC importer system in the second step that is the critical factor in determining which molecules from the CGTase activity will be internalized by the cell. Here, structure-function relationship studies of the cyclo⁄maltodextrin-binding protein MdxE of the MdxEFG-MsmX importer system from Thermoanaerobacter mathranii subsp. mathranii A3 are presented. Calorimetric and fluorescence studies of recombinant MdxE using linear dextrins and CDs showed that although MdxE binds linear dextrins and CDs with high affinity, the open-to-closed conformational change is solely observed after α- and β-CD binding, suggesting that the CM-CD pathway from Thermoanaerobacterales is exclusive for cellular internalization of these molecules. Structural analysis of MdxE coupled with docking simulations showed an overall architecture typically found in sugar-binding proteins (SBPs) that comprised two N- and C-domains linked by three small hinge regions, including the conserved aromatic triad Tyr193/Trp269/Trp378 in the C-domain and Phe87 in the N-domain involved in CD recognition and stabilization. Structural bioinformatic analysis of the entire MdxFG-MsmX importer system provided further insights into the binding, internalization, and delivery mechanisms of CDs. Hence, while the MdxE-CD complex couples to the permease subunits MdxFG to deliver the CD into the transmembrane channel, the dimerization of the cytoplasmatic promiscuous ATPase MsmX triggers active transport into the cytoplasm. This research provides the first results on a novel thermofunctional SBP and its role in the internalization of CDs in extremely thermophilic bacteria.

Bridges crossing rivers wider than 50 m are typically supported by piers. In a mobile riverbed, scour occurs around bridge piers, and it is the main cause of bridge collapses worldwide, especially during floods. While bridge pier scour has been extensively studied, there is still a lack of measuring systems for scour monitoring in the field. In this paper, we present existing devices for scour measurement and analyze their comparative advantages and disadvantages. A study case with a scoured bridge pier in supercritical flow is presented. Results show that supercritical flow patterns previously reported at the laboratory scale also occur in the field. The measured scour supports the hypothesis that supercritical flows, even when having high flow speeds, do not produce higher scour than subcritical flows. A possible explanation linked with the sediment sizes of rivers with supercritical flows is discussed. Further, field measurements of scour around bridge piers are needed to enhance our understanding of this complex and nearly unexplored situation.

Abstract Background Fragmentation (establishment of barriers e.g., hydropower dams, reservoirs for irrigation) is considered one of the greatest threats to conservation of river systems worldwide. In this paper we determine the fragmentation status of central Chilean river networks using two indices, namely Fragmentation Index (FI) and Longest Fragment (LF). These are based on the number of barriers and their placement as well as river length available for fish movement. FI and LF were applied to eight Andean river basins of central Chile in order to assess their natural, current (2018) and future (2050) fragmentation at the doorstep of a hydropower boom. Subsequently, we exemplify the use of these indices to evaluate different placement scenarios of new hydropower dams in order to maximize hydropower use and at the same time minimize impact on fish communities. Results In the natural scenario 4 barriers (waterfalls) were present. To these 4 barriers, 80 new ones of anthropogenic origin were added in the current (2018) scenario, whereas 377 new barriers are expected in near future (2050). Therefore, compared to the ‘natural’ scenario, in 2050 we expect 115-fold increase in fragmentation in analysed river systems, which is clearly reflected by the increase of the FI values in time. At the same time, the LF diminished by 12% on average in the future scenario. The fastest increase of fragmentation will occur in small and medium rivers that correspond to 1st, 2nd and 3rd Strahler orders. Finally, case study on configuration of potential hydropower plants in the Biobío basin showed that hydropower output would be maximized and negative effects on fish communities minimised if new hydropower plants would be located in tributaries of the upper basin. Conclusions Fragmentation of Chilean Andean river systems is expected to severely increase in near future, affecting their connectivity and ecological function as well as resilience to other anthropogenic stressors. Indices proposed here allowed quantification of this fragmentation and evaluation of different planning scenarios. Our results suggest that in order to minimise their environmental impact, new barriers should be placed in tributaries in the upper basin and river reaches above existing barriers.

Exact knowledge of the physical structures of different river sections that govern their ecological structure and function is essential for the efficient conservation and management of riverine ecosystems. Eleven Andean river basins (Maipo, Rapel, Mataquito, Maule, Itata, Biobío, Toltén, Valdivia, Bueno and Puelo) comprise large scale latitudinal and altitudinal gradients and accommodate 71% of the Chilean population that strongly depend on their ecosystem services. Here, based on 16 hydrogeomorphic variables (on basin, valley and channel scales), we assessed the riverine landscapes (Functional Process Zones; FPZs) of these river basins using a top-down multivariate statistical approach. Two steep valley and downstream slope FPZs, three sinuous FPZs and two braided FPZs emerged in 8906 river sections. The proportion of the occurrence of FPZs was characterised by a clear latitudinal pattern which is strongly related to the proportions of each river basin within the large morphostructural units of Chile. As such, the proportion of each river basin within the Andes Cordillera, Central Valley and Coastal Cordillera is a strong driver of the fluvial geomorphology and, thus, of the FPZs’ arrangement in each river network. FPZ classification captured geomorphic diversity that coincided with the latitudinal and altitudinal gradients of Chilean Andean river basins strongly related to the hydrological characteristics of the assessed river basins and large scale spatial distribution of fish fauna endemism. As such, the identified large geomorphic units (FPZs) that are strongly tied up with hydrology and ecology hierarchies of riverine landscape provide robust operational tools that can be instrumental for river ecosystem monitoring and management at a basin scale.

The Palais des Machines of the Paris Universal Exposition of 1889, designed by the architect Charles Louis Ferdinand Dutert (1845-1906) and the engineer Victor Contamin (1840-1893), is undoubtedly an icon of the 19th century architecture: its powerful spatiality, its portentous structure and its straightforward tectonics have rightly received high praise by critics and architects from the second half of the 20th century. However, critical tradition and historiography from the end of the last century have frequently offered a biased interpretation of this work, aimed at underlining certain architectonic values for then presenting them as a direct product of the author’s will. The aim of this article is to explain, altogether and with maximum transparency, how the conjunction between certain circumstantial issues and the will/ability of both authors made possible the construction of one of the most important works of the nineteenth-century architecture. To achieve this, the three most celebrated architectural aspects of the building are analysed: the huge scale of the central space, the particular structural system chosen and the uneven usage of ornament.

Bedforms-ATM (Bed forms analysis toolkit for multiscale modeling) is a software designed to hierarchize and quantify the dimensionality of natural bed forms fields. It comprises four modular applications, namely: (1) wavelet analysis, (2) Hovmöller analysis, (3) multiscale discrimination, and (4) three-dimensionality analysis. Bedforms-ATM also provides insights on bed form systems dynamics and their interrelationship with the surrounding hydrodynamic characteristics. The software structure encourages its expandability via the collaboration from the community of users. Both fluvial and synthetic bed form data accompany Bedforms-ATM. Keywords: Bed forms, Hierarchization, Dimensionality

Alloy 21-6-9 is an austenitic stainless steel with high strength, thermal stability at high temperatures, and retained toughness at cryogenic temperatures. This type of steel has been used for aerospace applications for decades, using traditional manufacturing processes. However, limited research has been conducted on this alloy manufactured using laser powder-bed fusion (LPBF). Therefore, in this work, a design of experiment (DOE) was performed to obtain optimized process parameters with regard to low porosity. Once the optimized parameters were established, horizontal and vertical blanks were built to investigate the mechanical properties and potential anisotropic behavior. As this alloy is exposed to elevated temperatures in industrial applications, the effect of elevated temperatures (room temperature and 750 °C) on the tensile properties was investigated. In this work, it was shown that alloy 21-6-9 could be built successfully using LPBF, with good properties and a density of 99.7%, having an ultimate tensile strength of 825 MPa, with an elongation of 41%, and without any significant anisotropic behavior.

There are many concepts for buildings with integrated renewable energy systems that have received increased attention during the last few years. However, these concepts only strive to streamline building-level renewable energy solutions. In order to improve the flexibility of decentralized energy generation, individual buildings and energy systems should be able to interact with each other. The positive energy district (PED) concept highlights the importance of active interaction between energy generation systems, energy consumers and energy storage within a district. This paper strives to inform the public, decision makers and fellow researchers about the aspects that should be accounted for when planning and implementing different types of PEDs in different regions throughout the European Union. The renewable energy environment varies between different EU regions, in terms of the available renewable energy sources, energy storage potential, population, energy consumption behaviour, costs and regulations, which affect the design and operation of PEDs, and hence, no PED is like the other. This paper provides clear definitions for different types of PEDs, a survey of the renewable energy market circumstances in the EU and a detailed analysis of factors that play an essential role in the PED planning process.

A new method for the optimization of seasonal energy storage is presented and applied in a case study. The optimization method uses an interval halving approach to solve computationally demanding mixed integer linear programming (MILP) problems with both integer and non-integer operation variables (variables that vary from time step to time step in during energy storage system operation). The seasonal energy storage in the case study uses a reversible solid oxide cell (RSOC) to convert electricity generated by solar photovoltaic (PV) panels into hydrogen gas and to convert hydrogen gas back to electricity while also generating some heat. Both the case study results and the optimization method accuracy are examined and discussed in the paper. In the case study, the operation of the RSOC and hydrogen storage system is compared with the operation of a reference system without energy storage. The results of the study show that installing an RSOC and hydrogen storage system could increase the utilization of onsite renewable energy generation significantly. Overall, the optimization method presents a relatively accurate solution to the case study optimization problem and a sensibility analysis shows a clear and logical pattern.

Scour, which represents a fascinating and complex engineering problem involving a number of physical mechanisms and interactions, has motivated a vast amount of research following different but complementary methodological approaches such as experimental, numerical, and field methods. Far from being completely understood, scour remains one of the main hazards for many structures such as bridges, submarine pipelines, offshore wind turbines, etc. Thus, scour is currently a very active field of research with important open questions that are unanswered and practical challenges to be tackled. This Special Issue aims to bridge knowledge gaps by collecting fourteen papers to provide a wide view of scour types and different research approaches, with innovative ideas and inferences.

El Pantheon de Adriano es una de las obras más celebradas de la historia de la arquitectura. Han sido muchas las cuestiones que han cautivado a cuantos han entrado en él, pero es la luz la que ha acaparado el mayor protagonismo: una vez despojado el edificio de su originaria carga simbólica, la manifestación de su luz interior parece ser el único fin de este inmenso espacio-luz que tanto ha fascinado a arquitectos, historiadores del arte, pintores y fotógrafos. Parece difícil poder aportar nada nuevo. Consciente de ello, el autor del presente artículo sólo pretende apuntar algunas cuestiones sobre distintos aspectos de la luz en el Pantheon que considera que no han sido aún suficientemente desarrolladas: el por qué de la orientación solar y urbana del templo con respecto al eje norte-sur; la reconstrucción de la secuencia de luz y sombra que debió de darse en el recorrido original de acceso al interior del templo; la interpretación del haz de luz ocular como reminiscencia inmaterial del soporte central de las falsas cúpulas etruscas, convertida en una columna de materia sutil que, sin alcanzar nunca la vertical, incide de manera variada sobre los paramentos que conforman el interior.

Se aplica el método de los volúmenes finitos para dar solución a las ecuaciones de Saint Venant 2D con términos fuente que gobiernan el escurrimiento de aguas someras, a fin de calcular el flujo inducido por el rompimiento de una presa. El modelo se verifica mediante el cálculo de siete casos con solución conocida, que son: (1) establecimiento del flujo normal a partir de una superficie libre horizontal; (2) establecimiento del flujo gradualmente variado en un canal con cambio de rugosidad; (3) escurrimiento sobre un obstáculo; (4) formación del salto hidráulico oblicuo; (5) oscilación amortiguada de la superficie libre en un estanque parabólico; (6) escurrimiento inducido por el rompimiento de una presa circular, y (7) escurrimiento inducido por el rompimiento parcial de una presa. El modelo se aplica para simular el flujo inducido por el rompimiento instantáneo de presas, a fin de analizar el efecto de la configuración geométrica del conjunto presa, embalse, valle y cauce sobre el hidrograma de salida. Se simularon 28 escenarios, considerando un valle con sección parabólica y un cauce con sección trapezoidal, donde se varió la altura y orientación del muro de la presa, el ancho de la brecha, la pendiente longitudinal y la rugosidad del cauce aguas abajo. Los resultados obtenidos muestran que la altura de la presa es la variable más influyente en el caudal máximo del hidrograma de salida y que el ancho de la brecha tiene un efecto importante en rompimientos parciales. La rugosidad del lecho atenúa de forma considerable el caudal máximo hacia aguas abajo y aumenta el tiempo de crecida. La orientación del muro y la pendiente longitudinal tienen un efecto menor sobre las crecidas provocadas por rompimiento. El modelo desarrollado predice de manera adecuada el complejo comportamiento que exhibe el flujo inducido por el rompimiento instantáneo de una presa, constituyendo una herramienta de simulación con capacidad predictiva.

The scour at bridge foundations caused by supercritical flows is reviewed and knowledge gaps are analyzed focusing on the flow and scour patterns, available measuring techniques for the laboratory and field, and physical and advanced numerical modeling techniques. Evidence suggests that the scour depth caused by supercritical flows is much smaller than expected, by an order of magnitude compared to that found in subcritical flows, although the reasons for this behavior remain still unclear. Important questions on the interaction of the horseshoe vortex with the detached hydraulic-jump and the wall-jet flow observed in supercritical flows arise, e.g., does the interaction between the flow structures enhance or debilitate the bed shear stresses caused by the horseshoe vortex? What is the effect of the Froude number of the incoming flow on the flow structures around the foundation and on the scour process? Recommendations are provided to develop and adapt research methods used in the subcritical flow regime for the study of more challenging supercritical flow cases.

To achieve sustainable development of hydroelectric resources, it is necessary to understand their availability, variability, and the expected impacts of climate change. Current research has mainly focused on estimating hydropower potential or determining the optimal locations for hydropower projects without considering the variability and historical trends of the resources. Herein, the hydropower potential variability from reconstructed streamflow series estimated with a non-parametric gap-filling method and geographic information systems (GIS) techniques are analyzed. The relationships between hydropower and large-scale climate variability, expressed by sea surface temperature, are explored. Finally, we project hydropower potential through 2050 using 15 global circulation models with representative concentration pathway (RCP) 4.5. We used four watersheds in central Chile as a case study. The results show significant interannual and inter-basin hydropower potential variability, with decreasing trends over time modulated by alternating positive and negative decadal trends; these modulations exhibit greater intensities than the general trends and are attributable to climatic oscillations such as El Niño. Future scenarios indicate high hydropower availability and a possible over-investment in hydroelectric plants in two of the four studied watersheds. Results show the need to improve the current policies that promote hydropower development including hydropower resource variability in order to achieve optimal, sustainable hydropower development worldwide.

Se aplica el método de los volúmenes finitos y se generaliza la estrategia ultimate para la solución de la ecuación advección-difusión-reacción con parámetros variables, a fin de obtener resultados con difusión numérica despreciable. El modelo se verifica mediante el cálculo de problemas con solución analítica conocida, mostrando su aptitud para simular el transporte difusivo y advectivo de propiedades escalares en el agua. Se aplica para calcular la temperatura en un tramo de 32 km del río Itata bajo, ubicado en Chile Central, donde se midió la temperatura del río y las variables que controlan el régimen térmico en varios puntos. Se presentan resultados para cuatro períodos de doce días de duración, correspondientes a escenarios de invierno, primavera, verano y otoño. La temperatura media medida en los escenarios de invierno y verano es constante, igual a 9.6 y 24.0°C, respectivamente, y no cambia a lo largo del tramo. En los escenarios medidos de otoño y primavera se observa un leve aumento a lo largo del tramo igual a 0.45 y 0.74°C, respectivamente. La amplitud de la oscilación térmica diaria medida en el escenario de invierno es despreciable, igual a 0.7°C y muy significativa en el de verano, igual a 8.4°C. Se observa que sólo en el escenario medido de verano dicha amplitud aumenta a lo largo del tramo de estudio, a razón de 0.175°C/km. El modelo desarrollado predice de manera adecuada el complejo comportamiento que exhibe la temperatura medida durante los cuatro escenarios analizados, constituyendo una herramienta de simulación con capacidad predictiva.

The manuscript reflects the opinion of the authors about the need for a hydromorphological approach for the management of Chilean rivers. A brief state-of-the-art of the recent scientific advances on hydromorphological approach to river management is presented, as well as a general overview of the conditions of Chilean rivers and the mayor disturbances they suffer. Moreover, the need to take into account both direct and indirect services provided by rivers in the decision making process on river management is underlined. Hydromorphology is claimed to be a main element to be considered while assessing the ecological state of rivers. Understanding how the hydrological and morphological variables interact dynamically is indeed key to assess the presence or absence of dynamic equilibrium, a condition that, in turn, promotes both habitat diversity and self-sustainable aquatic and riparian ecosystems. The authors also emphasized the need for a change of paradigm in current Chilean rivers management practices, by developing a unified framework to assess hydromorphological and ecological river conditions. In addition, the implementation of specific legislation aimed at promoting ecological and geomorphological standards in river management practice, and the strengthening and widening of the academic teaching of fluvial ecology and geomorphology is suggested.El manuscrito refleja la opinión de los autores acerca de la necesidad de aplicar un enfoque hidromorfológico para la gestión de los ríos chilenos. Se presenta una breve reseña de los últimos avances científicos sobre el enfoque hidromorfológico en la gestión de ríos, así como una visión general de las condiciones de los ríos chilenos y sus mayores perturbaciones. Por otra parte, se hace énfasis en la necesidad de incluir en la toma de decisiones los servicios directos como los indirectos proporcionados por los ríos. Se afirma que la hidromorfología es un elemento fundamental a considerar al determinar el estado ecológico de los ríos. La comprensión de cómo las variables hidrológicas y morfológicas interactúan de forma dinámica es sin duda clave para evaluar la presencia o ausencia de un equilibrio dinámico, una condición que, a su vez, fomenta tanto la diversidad de hábitat como el desarrollo sostenible de los ecosistemas acuáticos y ribereños. Los autores concluyen que es necesario cambiar el paradigma actual de gestión aplicado en los ríos chilenos desarrollando una estrategia que permita evaluar las condiciones hidromorfológicas y ecológicas de los ríos. Además, sugieren implementar legislación específica orientada a promover estándares ecológicos y geomorfológicos en la práctica de gestión, con el apoyo de un fortalecimiento y una ampliación de la enseñanza académica de la geomorfología y ecología fluvial.

Based on recent contributions regarding the treatment of unsteady hydraulic conditions in the state-of-the-art scour literature, theoretically derived probability distribution of bridge scour is introduced. The model has been derived assuming a rectangular hydrograph shape with a given duration, and a random flood peak, following a Gumbel distribution. A model extension for a more complex flood event has also been presented, assuming a synthetic exponential hydrograph shape. The mathematical formulation can be extended to any flood-peak probability distribution. The aim of the paper is to move forward the current approaches adopted for the bridge design, by coupling hydrological, hydraulic, and erosional models, in a mathematical closed form. An example of the application of the proposed distribution has been included with the aim to provide a guidance for the parameters estimation.

A cache appliance is a network terminal which provides cache memory functions, such as object queries service from a user; such objects could be stored in one cache or in a cache hierarchy, trying to avoid carry out service from an origin server. This cache appliance structure improves network performance and quality of service. These appliances use ICP protocol (Internet Cache Protocol) to support interoperation between existing cache hierarchies and web servers, through implementation of a message format to communicate web caches. One cache sends an ICP query to its neighbors. The neighbors send back ICP replies indicating "HIT" or "MISS". When one cache faces an excessive traffic situation, that is, a very high number of service queries from users, ICP protocol may allocate the service to cache which has the desired object. Because of traffic conditions, specific appliance may congests and the requests may be refused, which can decrease network's quality of service. So, a system designed for optimizing cache allocation, considering factors as traffic and priority could be useful. This paper presents a fuzzy inference system design, which uses entries such as number of queries over a time interval and traffic tendency, and as output, the web cache allocation decision that will provides the service; this design is proposed to optimize allocation of caches into a hierarchy for network services performance, so balancing out requesting among hierarchy members and improving services performance.