191 research outputs found
Constructive Analysis of Maya Vaulted Architecture from Photogrammetric Survey
[EN] Studying Maya architecture from a constructive perspective reveals new insights into the ancient building techniques and processes. Gaining deep knowledge of these structures is key to assessing the current conservation state of the buildings and to designing strategies for the excavation and preservation of this heritage. In order to study the Maya vault system, considering its regional variants and technical development over time, we performed field data collections at 48 Maya Lowlands archaeological sites with the aim of documenting and comparing constructive techniques from different areas and chronological periods. Surveying some of these buildings with digital photogrammetry made it possible to obtain geometrically accurate models with a high-quality texture that were used to measure, analyze and compare the features of the vaults in detail. The main advantage of this survey methodology is that it permits to achieve a high amount of information with affordable instruments. From the models obtained, a thorough analysis of stonemasonry techniques, stereotomy solutions and building processes was carried out, considering their implications for the stability and conservation of the structures. This paper presents the survey methodology used and an example of the constructive analysis of a vaulted building from a photogrammetric model.This work was funded by the Spanish Ministry of Science,
Innovation and Universities through the Aid Program for pre-doc
contracts for training of doctors (ref. BES-2015-071296); by the
Universitat Politècnica de València through the Research and
Development Grants Program (PAID-01-17) and by Generalitat
Valenciana through the Santiago Grisolía grants Program
(GRISOLIAP/2018/139). The study is part of the research project
Arquitectura Maya: Sistemas Constructivos, Estética Formal,
Simbolismo y Nuevas Tecnologías (PGC2018-098904-B-C21-
AR), funded by the Spanish Ministry of Science, Innovation and
Universities.Gilabert Sansalvador, L.; Montuori, R.; Rosado-Torres, AL. (2020). Constructive Analysis of Maya Vaulted Architecture from Photogrammetric Survey. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (Online). 44:357-363. https://doi.org/10.5194/isprs-archives-XLIV-M-1-2020-357-2020S3573634
3D Printing for Dissemination of Maya Architectural Heritage: The Acropolis of La Blanca (Guatemala)
[EN] This paper focuses on the use of 3D printing as a tool for the dissemination of Maya architectural heritage. The case study is the Acropolis of La Blanca, the main complex of this archaeological site located in the Peten department, Guatemala. One of the objectives of La Blanca Project was to create a model of the Acropolis as part of the strategy for dissemination and as a didactical resource for the Visitor Center. The documentation of this architectural complex with digital survey techniques allowed to obtain a high-fidelity model of the Acropolis¿ buildings. In order to achieve this goal, it was necessary to develop a methodology for the reverse modelling of the Acropolis, starting from the data obtained by laser scanning. We developed a workflow to create a virtual replica of the Acropolis optimized for 3D printing. This model was first printed in 17 parts by using the FDM technology. Then, it was transported to Guatemala and, finally, it was reassembled and placed at the Visitor Center. Today, this physical replica of the Acropolis is an important resource that allows the visitors to have a complete view of the main complex of the site, which is not easy in the Guatemalan jungle. It also provides an exclusive view of some parts of the Acropolis, already studied by researchers and now protected with a soil layer to ensure their preservation. Moreover, it is a useful resource for supporting dissemination and also serves as a teaching resource for student visitors.This work was funded by the Universitat Politècnica de
València through the Research and Development Grants
Program (PAID-01-17); by the Spanish Ministry of Science,
Innovation and Universities through the Aid Program for predoc contracts for the training of doctors (ref. BES-2015-
071296) and by Generalitat Valenciana through the Santiago
Grisolía grants Program (GRISOLIAP/2018/139).
This study is also part of the research project Arquitectura
Maya: Sistemas Constructivos, Estética Formal, Simbolismo y
Nuevas Tecnologías (PGC2018-098904-B-C21-AR), funded
by the Spanish Ministry of Science, Innovation and
Universities.Montuori, R.; Gilabert Sansalvador, L.; Rosado-Torres, AL. (2020). 3D Printing for Dissemination of Maya Architectural Heritage: The Acropolis of La Blanca (Guatemala). International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (Online). 44:481-488. https://doi.org/10.5194/isprs-archives-XLIV-M-1-2020-481-2020S4814884
Transformations in the Architecture of E-Groups: The Cases of Tikal and Uaxactun
[ES] Los grupos E son una tipología muy singular en la arquitectura maya. Estos conjuntos están formados por una plaza central delimitada a un costado por un edificio piramidal, y al otro por una plataforma alargada que generalmente soporta tres estructuras. Esta denominación se originó en Uaxactún, por la nomenclatura otorgada al primer conjunto identificado con tales características. En 1924, Frans Blom observó que, mirando desde la pirámide, era posible ver la alineación del sol sobre las tres estructuras al este durante los solsticios y los equinoccios, y sugirió que podría tratarse de un complejo de observación del ciclo solar. Después, se han realizado diversos estudios arqueológicos y arqueo-astronómicos que han llevado a la formulación de hipótesis diferentes, incluso a veces conflictivas, sobre la posible función de estos conjuntos. Los edificios que forman parte de los grupos E fueron sometidos en el tiempo a varias transformaciones, una práctica muy común en la arquitectura maya que, en muchos casos, comprendía la clausura y el rellenado de las estructuras preexistentes para ser después incorporadas en el volumen del nuevo edificio. Las remodelaciones que los constructores mayas aportaron en el tiempo alteraron tanto las dimensiones como las relaciones espaciales entre los edificios de estos conjuntos, generando una compleja superposición de fases constructivas. En este trabajo analizamos y comparamos desde un punto de vista arquitectónico los edificios de los grupos E de Mundo Perdido en Tikal, y de Uaxactún, centrándonos en su evolución constructiva.[EN] E-Groups are a unique typology in Maya architecture. These complexes consist of a central plaza delimited by a pyramidal building on the one side and by an elongated platform supporting three structures on the other side. Originated in Uaxactun, this denomination came from the nomenclature given to the first group ever identified with such characteristics. The interpretation of E-Groups began in 1924, with Frans Blom¿s studies of what seemed to be a solar cycle observation complex. He observed that, looking from the pyramid, it was possible to see the alignment of the sun over the three structures to the east during the solstices and equinoxes. Several archaeological and archaeoastronomical studies have been carried out ever since, which have led to the formulation of different, sometimes even controversial hypotheses about their possible function.
E-Groups¿ buildings suffered various transformations over time, a very common practice in Maya architecture, which in many cases involved the filling and closure of pre-existing structures, later incorporated in the new building. The modifications that Maya builders brought about over time altered both the dimensions and the spatial relations between the buildings in these complexes, thus creating a complex superposition of constructive phases. In this paper, we analyze and compare, from an architectural point of view, the buildings of E-Groups in Mundo Perdido in Tikal and in Uaxactún, focusing on their constructive evolution.Los autores agradecen expresamente el apoyo
del Ministerio de Ciencia, Innovación y Universidades
de España a través de la financiación del proyecto
de investigación "Arquitectura maya. Sistemas
constructivos, estética formal, simbolismo y nuevas
tecnologías" (PGC2018-098904-B-C21-AR), así como
de la Universitat Politècnica de València a través del
Programa de Ayudas de Investigación y Desarrollo para
la Formación de Personal Investigador (PAID-01-17) y
de la Generalitat Valenciana a través del Programa
de ayudas Santiago Grisolía (GRISOLIAP/2018/139),
que han contribuido de forma determinante a hacer
posibles las investigaciones y la obtención de los
resultados que se exponen en esta publicación.Montuori, R.; Rosado-Torres, AL. (2021). Transformaciones en la arquitectura de los grupos E: los casos de Tikal y Uaxactún. Gremium. 8(15):113-130. http://hdl.handle.net/10251/176532S11313081
Digitizing an Excavation: A Laser Scanning Database of Maya Architectural Remains
Excavating an ancient Maya city requires a long-term archaeological project that entails adequate documentation procedures for the unearthed remains, frequently of monumental scale and with difficult preservation conditions. A digital laser scanner survey methodology was designed and implemented to document the exposed architecture and to follow-up the archaeological excavation of the Maya site of La Blanca (Peten, Guatemala). All scans collected during the different field seasons were stored and aligned in a common reference system. Thus, an accurate digital three-dimensional database was obtained, including all the architectural remains found, some of which had to be reburied to ensure their preservation. The resulting database is a helpful repository that facilitates to extract all the graphic outputs required for: planning the next excavation campaigns, monitoring the preservation of the buildings, studying the architecture and construction technology in detail, and disseminating the excavation results. This paper describes the methodology and procedures used to build-up this database
Effectiveness of Fosfomycin for the Treatment of Multidrug-Resistant Escherichia coli Bacteremic Urinary Tract Infections
IMPORTANCE The consumption of broad-spectrum drugs has increased as a consequence of the spread of multidrug-resistant (MDR) Escherichia coli. Finding alternatives for these infections is critical, for which some neglected drugs may be an option. OBJECTIVE To determine whether fosfomycin is noninferior to ceftriaxone or meropenem in the targeted treatment of bacteremic urinary tract infections (bUTIs) due to MDR E coli. DESIGN, SETTING, AND PARTICIPANTS This multicenter, randomized, pragmatic, open clinical trial was conducted at 22 Spanish hospitals from June 2014 to December 2018. Eligible participants were adult patients with bacteremic urinary tract infections due to MDR E coli; 161 of 1578 screened patients were randomized and followed up for 60 days. Data were analyzed in May 2021. INTERVENTIONS Patients were randomized 1 to 1 to receive intravenous fosfomycin disodium at 4 g every 6 hours (70 participants) or a comparator (ceftriaxone or meropenem if resistant; 73 participants) with the option to switch to oral fosfomycin trometamol for the fosfomycin group or an active oral drug or pa renteral ertapenem for the comparator group after 4 days. MAIN OUTCOMES AND MEASURES The primary outcome was clinical and microbiological cure (CMC) 5 to 7 days after finalization of treatment; a noninferiority margin of 7% was considered. RESULTS Among 143 patients in the modified intention-to-treat population (median [IQR] age, 72 [62-81] years; 73 [51.0%] women), 48 of 70 patients (68.6%) treated with fosfomycin and 57 of 73 patients (78.1%) treated with comparators reached CMC (risk difference, -9.4 percentage points; 1-sided 95% CI, -21.5 to infinity percentage points; P = .10). While clinical or microbiological failure occurred among 10 patients (14.3%) treated with fosfomycin and 14 patients (19.7%) treated with comparators (risk difference, -5.4 percentage points; 1-sided 95% CI. -infinity to 4.9; percentage points; P = .19), an increased rate of adverse event-related discontinuations occurred with fosfomycin vs comparators (6 discontinuations [8.5%] vs 0 discontinuations; P = .006). In an exploratory analysis among a subset of 38 patients who underwent rectal colonization studies, patients treated with fosfomycin acquired a new ceftriaxone-resistant or meropenem-resistant gram-negative bacteria at a decreased rate compared with patients treated with comparators (0 of 21 patients vs 4 of 17 patients [23.5%]; 1-sided P = .01). CONCLUSIONS AND RELEVANCE This study found that fosfomycin did not demonstrate noninferiority to comparators as targeted treatment of bUTI from MDR E coli; this was due to an increased rate of adverse event-related discontinuations. This finding suggests that fosfomycin may be considered for selected patients with these infections
Role of age and comorbidities in mortality of patients with infective endocarditis
[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality.
[Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk.
[Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality.
[Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group
Ciencia Odontológica 2.0
Libro que muestra avances de la Investigación Odontológica en MéxicoEs para los integrantes de la Red de Investigación en Estomatología (RIE) una enorme alegría presentar el segundo de una serie de 6 libros sobre casos clínicos, revisiones de la literatura e investigaciones. La RIE está integrada por cuerpos académicos de la UAEH, UAEM, UAC y UdeG
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study
Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research
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