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Exploring the reproductive ecology of the tropical semifossorial snake Ninia atrata

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Zoological Research 2020年第2期41卷 157-171页

作者： Teddy Angarita-Sierra Cesar Alejandro Lopez-hurtado Tropical Organism Biology Research Group Universidad Nacional de ColombiaBogota111321Colombia Yoluka ONG Fundacion de Investigacion en Biodiversidad y ConservacionBogota110931Colombia Vicerrectoria de Investigacion Universidad Manuela BeltranBogota110231Colombia

Based on histological analyses and field studies,this research describes the reproductive ecology of a population of Ninia atrata snakes inhabiting an oil palm ***,through a multivariate approach,we explored the main drivers of reproductive output in *** showed that prey abundance and food intake were crucial variables contributing to reproductive *** linear regression models showed that neonates had high sensitivity(R2=55.29%)to extreme changes in climate,which was strongly related to slug and snail abundance variability and microhabitat *** cycles were markedly different between the sexes,being continuous in males and cyclical in *** this variation,reproductive cycles at the population level were seasonal *** recruitment of neonates all year,multiple clutches,high mating frequency,and continuous sperm production characterized the reproductive phenology of *** addition,a significant number of previtellogenic females presented oviductal sperm as well as uterine scars,suggesting a high precocity in the *** main drivers of reproductive output also differed between the *** females,clutch size and secondary follicle variability were highly related to stomach bolus volume,fat body area,and body *** males,height of piles of palm leaves and body mass,rather than intrinsic reproductive traits,were the main drivers of sperm ***,in both cases,the relationship between body mass,prey abundance,and food intake suggests that *** follows the income breeding strategy to compensate for reproductive costs and to maximize fitness.

关键词： Continuous male reproduction Clutch mass Income breeding Iteroparity Spermatogenesis Oogenesis Reproductive effort El Nino-Southern Oscillation(ENSO)

Effect of grain recrystallization on stir zone and mechanical property behavior of TRIP 780 steel

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Journal of Iron and Steel Research International 2020年第2期27卷 188-196页

作者： Gladys Perez-Medina Hugo Lopez Argelia Miranda-Perez Eduardo hurtado-Delgado Postgraduate Studies Mexican Corporation in Materials ResearchSaltillo Coahuila 25290Mexico Materials Department University of Wisconsin-MilwaukeeMilwaukeeWI 53201USA

Electron backscatter diffraction(EBSD)and transmission electron microscopy were used to determine the presence of retained austenite and displacive-type phase transformation in the stir zone of friction stir welding(FSW).Severe plastic deformations occurred in the stir zone where there was an increase in the temperature attributed to the FSW process and subsequently a grain *** the recrystallization phenomena,the formation of grain evolution development in steels was resolved using *** addition,a tensile test was carried out in order to reveal the results of mechanical *** was found that the fracture zone occurred in the stir zone with an ultimate tensile strength of 587 MPa,a decrease of 267 MPa compared with that of the base *** this result,it is evident that the fracture exhibits numerous elongated dimples,distributed homogeneously,and certain locations contain cleavage fractures due to differences in the microstructure of the base *** profile tests of the welding regions were conducted,and the results showed that the stir zone was present with elevated hardness(near 350 HV).Characterization techniques revealed that the austenite-to-martensite transformation occurred in the stir zone,resulting in a loss of mechanical properties in the joint.

关键词： Friction welding Transformation-induced plasticity steel Stir zone Mechanical property Tensile test

Discovery of gargantulides B and C,new 52-membered macrolactones from Amycolatopsis *** absolute stereochemistry of the gargantulide family

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Organic Chemistry Frontiers 2022年第2期9卷 462-470页

作者： Daniel Carretero-Molina Francisco Javier Ortiz-López Tetiana Gren Daniel Oves-Costales Jesús Martín fernando Román-hurtado Tue Sparholt Jorgensen Mercedes de la Cruz Caridad Díaz Francisca Vicente Kai Blin fernando Reyes Tilmann Weber Olga Genilloud Fundación MEDINA Centro de Excelencia en Investigación de Medicamentos Innovadores en AndalucíaAvda.del Conocimiento 3418016 ArmillaGranadaSpain The Novo Nordisk Foundation Center for Biosustainability Technical University of DenmarkKemitorvetbuilding 2202800 Kgs.LyngbyDenmark

Gargantulides B and C,two new and highly complex 52-membered glycosylated macrolactones,were isolated from Amycolatopsis *** CA-230715 during an antibacterial screening *** structures of these giant macrolides were elucidated by 2D NMR spectroscopy and shown to be related to gargantulide A,although containing additional β-glucopyranose and/orα-arabinofuranose monosaccharides separately attached to their *** sequencing allowed the identification of a strikingly large 216 kbp biosynthetic gene cluster,among the largest type Ⅰ PKS clusters described so far,and the proposal of a previously unreported biosynthetic pathway for gargantulides *** absolute configurations of gargantulides B and C were assigned based on a combination of NMR and bioinformatics analysis of ketoreductase and enoylreductase domains within the multimodular type Ⅰ *** addition,the absolute stereochemistry of gargantulide A has now been revised and *** B and C display potent antibacterial activity against a set of drug-resistant Gram-positive bacteria and moderate activity against the clinically relevant Gram-negative pathogen Acinetobacter baumannii.

关键词： absolute membered backbone

Experimental investigation of gaseous solvent huff-n-puff in the Middle Bakken Formation

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Petroleum Science 2023年第6期20卷 3488-3497页

作者： Samuel Asante Afari Kegang Ling Demetrius Maxey Billel Sennaoui Jerjes hurtado Porlles Department of Petroleum Engineering University of North Dakota2844 Campus RdStop 8154Grand ForksND58202-6116USA

The efficacy of gaseous solvents in enhancing oil recovery(EOR)in unconventional reservoirs and the influence of operational and design parameters are still debated among the oil recovery research *** work investigated the recovery-enhancing capabilities of two potent gaseous solvents,CO_(2) and ethane,in tight core *** huff-n-puff(H-n-P)experiments were conducted under three miscibility conditions to investigate the influence of the key operating parameters and the dependency of their impact on the miscibility conditions and gas *** results show that oil recovery increased with increasing pressure from below(BM)to above(AM)miscibility pressure in a non-linear trend,irrespective of the gas ***,the influence of the soak period was noticeably dependent on the miscibility condition,specifically more remarkable under AM conditions and less apparent under BM ***,the effect of the production period was more pronounced at AM conditions for both ***,the impact of rock surface area-to-volume(SA/V)was only observed at BM,where both gases recovered more oil in the core samples with high SA/*** general,ethane showed a higher efficacy for oil recovery than CO_(2);CO_(2) recovered 21%–70%of oil in small core samples,while ethane could recover 32%–88%.The highest recovery was achieved with ethane injected under AM conditions,with a prolonged soak time,a short production period and into a core sample with a high SA/*** believe the findings from this work will help better understand and design H-n-P EOR projects.

关键词： Unconventional reservoirs Huff-n-puff Gas solvent Ethane CO_(2)miscibility

Foreign exchange trading and management with the stochastic dual dynamic programming method

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Financial Innovation 2023年第1期9卷 583-620页

作者： Lorenzo Reus Guillermo Alexander Sepulveda‑hurtado Escuela de Negocios Universidad Adolfo IbanezDiagonal Las Torres2640 SantiagoChile

We present a novel tool for generating speculative and hedging foreign exchange(FX)trading *** solution provides a schedule that determines trades in each rebalancing period based on future currency prices,net foreign account positions,and incoming(outgoing)flows from business *** obtain such policies,we construct a multistage stochastic programming(MSP)model and solve it using the stochastic dual dynamic programming(SDDP)numerical method,which specializes in solving high-dimensional MSP *** construct our methodology within an open-source SDDP package,avoiding implementing the method from *** measure the performance of our policies,we model FX prices as a mean-reverting stochastic process with random events that incorporate stochastic *** calibrate this price model on seven currency pairs,demonstrating that our trading policies not only outperform the benchmarks for each currency,but may also be close to ex-post optimal *** also show how the tool can be used to generate more or less conservative strategies by adjusting the risk tolerance,and how it can be used in a vari-ety of contexts and time scales,ranging from intraday speculative trading to monthly hedging for business ***,we examine the impact of increasing trade policy uncertainty(TPU)levels on our *** findings show that the volatility of currencies from emerging economies rises in comparison to currencies from devel-oped *** discover that an increase in the TPU level has no effect on the aver-age profit obtained by our ***,the risk exposure of the policies increases(decreases)for the group of currencies from emerging(developed)markets.

关键词： FX trading FX risk SDDP Multistage stochastic programming Julia Trade policy uncertainty

Gut microbiota-related complications in cirrhosis

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World Journal of Gastroenterology 2014年第42期20卷 15624-15631页

作者： Isabel Gómez-hurtado José Such Yolanda Sanz Rubén Francés CIBERehd-Liver Unit Hospital General Universitario Alicante Instituto de Agroquímica y Tecnología de los Alimentos Consejo Superior de Investigaciones Científicas (IATACSIC) Carrer Catedràtic Agustín Escardino Benlloch

Gut microbiota plays an important role in cirrhosis. The liver is constantly challenged with commensal bacteria and their products arriving through the portal vein in the so-called gut-liver axis. Bacterial translocation from the intestinal lumen through the intestinal wall and to mesenteric lymph nodes is facilitated by intestinal bacterial overgrowth, impairment in the permeability of the intestinal mucosal barrier, and deficiencies in local host immune defences. Deranged clearance of endogenous bacteria from portal and systemic circulation turns the gut into the major source of bacterialrelated complications. Liver function may therefore be affected by alterations in the composition of the intestinal microbiota and a role for commensal flora has been evidenced in the pathogenesis of several complications arising in end-stage liver disease such as hepatic encephalopathy, splanchnic arterial vasodilatation and spontaneous bacterial peritonitis. The use of antibioticsis the main therapeutic pipeline in the management of these bacteria-related ***,other strategies aimed at preserving intestinal homeostasis through the use of pre-,pro-or symbiotic formulations are being studied in the last *** this review,the role of intestinal microbiota in the development of the most frequent complications arising in cirrhosis and the different clinical and experimental studies conducted to prevent or improve these complications by modifying the gut microbiota composition are summarized.

关键词： Cirrhosis Encephalopathy Portal hypertension Spontaneous bacterial peritonitis Microbiota Bacterial translocation

Limitations in tracking systems

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控制理论与应用（英文版） 2010年第3期8卷 351-358页

作者： Ivan Lopez hurtado Chaouki T.ABDALLAH Sudharman K.JAYAWEERA Department of Engineering Northern New Mexico College Department of Electrical & Computer Engineering University of New Mexico

In this paper, we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mutual information rate between the feedback signal and the reference input signal is used to quantify information about the reference signal that is available for feedback. This mutual information rate must be maximized in order to improve the tracking performance. The mutual information is shown to be upper bounded by a quantity that depends on the unstable eigenvalues of the plant and on the channel capacity. If the channel capacity reaches a lower limit, the feedback signal becomes completely uncorrelated with the reference signal, rendering feedback useless. We also find a lower bound on the expected squared tracking error in terms of the entropy of a random reference signal. We show a misleading case where the mutual information rate does not predict the expected effect of nonminimum phase zeros. However, mutual information rate helps generalize the concept that there is a tradeoff when tracking and disturbance rejection are simultaneous goals, and a constraint communication channel is present in the feedback loop. Examples and simulations are provided to demonstrate some of the results.

关键词： Limited channel capacity Tracking systems Constraint feedback

Rheological characterization of A201 aluminum alloy

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1638-1642页

作者： A.BLANCO Z.AZPILGAIN J.LOZ ARES P.KAPRANOS I.hurtado Mechanical and Manufacturing Department Faculty of EngineeringMondragon Unibertsitatea

The thermodynamic characterization as well as the rheological characterization of the A201 alloy were *** simulations (CALPHAD method) and calorimetric experiments were performed to determine the solidus and liquidus temperatures, the melting range and the sensitivity of the solid fraction at the thixoforming *** rheology of aluminium alloy A201 was examined using a high temperature Searle *** flow behaviour was analyzed with concentric cylinders of graphite to avoid chemical interactions with the liquid or semi-solid *** rotational body was grooved to prevent a phenomenon called wall *** cooling experiment was used to observe the shear rate effects on the flow *** can be seen that the viscosity level decreases at higher shear *** rate jump experiment was carried out to evaluate the steady state flow curve within the analyzed shear rate range from 60 s-1 to 260 *** is found that the power law indexes are-1.35 and-1.49 for 35% and 45% solid fraction, ***, some mechanical property data of as-cast and as-thixoformed A201 alloy are included indicating the potential for high strength applications.

关键词： aluminum alloys rheology mechanical properties semi-solid metal tixotropy shear-thinning

Kentish Plover(Charadrius alexandrinus) and Little Tern(Sternula albifrons) prefer shells for nesting:A field experiment

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Avian Research 2024年第1期15卷 55-59页

作者： Macarena Castro Andrés De la Cruz Nuria Martin-Sanjuan Alejandro Pérez-hurtado Instituto Universitario de Investigacion Marina(INMAR) Campus de Excelencia Internacional del Mar(CEIMAR)Departamento de BiologíaUniversidad de CadizPuerto RealSpain Servicios centrales de Investigacion Salinas de la Esperanza Universidad de CadizPuerto RealSpain

Shorebird populations are declining worldwide,mainly due to human disturbances and loss of coastal ***,supratidal habitats as saltpans could play a role in buffering human *** have shown to be important as feeding or breeding sites of some shorebird species.A potential conservation strategy to increase shorebird populations in saltpans is to manipulate the cues that birds use to select optimal breeding *** it is hypothesized that shorebirds are attracted to bivalve shells due to the advantages they *** this hypothesis,we supplemented a restored saltpan in 2019 and 2021 with bivalve shells,expecting an increase in the number of breeding birds’ *** than 75% of Kentish Plover(Charadrius alexandrinus) and Little Tern(Sternula albifrons) nests were found in patches with shells in both *** best model for both species indicates that the presence of shells is the factor that most correlates with the location of *** probability of choosing one place over another to settle their nest increases in areas with an abundance of shells,double in the case of the Kentish Plover and triple in the case of the Little *** result of this study may constitute a valuable tool for attracting birds to restored saltpans and could contribute to the success of expensive restoration projects where time is usually a constraint.

关键词： Habitat management Nest site selection Saltpan restoration Shell supplementation Shorebirds