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POR: Juan Tolentino Morales VENTAJAS. Michel Pozas Lucic, de A.P. Moller-Maersk, señala las oportunidades que genera México para la empresa. (FOTO: RAFA MONTIEL) La premisa de que el transporte aéreo [...]

POR: Juan Tolentino Morales La recuperación hotelera luego de la pandemia no es ningún secreto. En México, la apertura de fronteras y el dinamismo de los mercados de sol y [...]

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THE CASE A woman, aged 44 years, presented at the general oncology outpatient clinic with bloating, abdominal pain, and significant unintended weight loss. Her past medical history included a bilateral [...]

A Sub-Nyquist Radio Frequency Pulse Width Modulation (RFPWM) technique, which extends the concept of Sub-Nyquist DACs to RFPWM, is introduced in this paper. The carrier frequency is selected as the ${k}$ -th order harmonic of the PWM switching frequency. This choice enables operation within an extended frequency range for a particular switching transistor in contrast to the conventional RFPWM approach, where the carrier and switching frequencies are identical. The feasibility of this methodology is verified by both extensive simulations and experimental measurements. While there is a reduction in output power proportional to the harmonic number, this approach has the potential to set the transmitted power to these fixed steps in an all-digital format without compromising spectral performance, as evidenced by comprehensive simulations. Furthermore, the method exhibits strong spectral performance within and outside the desired frequency bands across different quantization scenarios, covering carrier frequencies up to four times the switching frequency. The proof of concept for Sub-Nyquist RFPWM transmitter is a fully digital field-programmable gate array (FPGA) implementation, enabling adaptability to multistandard signals. The pulse position/pulse-width modulation is based on an outphasing approach, using the FPGA transceivers to generate the high-speed binary waveform. Measurements were carried out using a 1.4-MHz LTE 64-QAM signal with a PWM switching frequency of 311 MHz, achieving ACPR values below −39 dBc when the second and third harmonics were used as carrier frequencies (622 MHz and 933 MHz, respectively).

Security and transient stability (TS) constrained OPFs do not include network switching and often require excessive computation time due to discretization of the TS model. This paper proposes a non-simulation methodology to optimize active power dispatching and network switching to ensure TS and system security in the preventive control mode. Network switching is introduced in the security constrained OPF and classical TS models, giving a general dynamic security and TS constrained OPF. To ensure TS constraints are manageable in the optimization framework, TS is assessed by using proposed non-simulation based proxy measures. To this end, the key factors impacting TS are investigated and new composite robustness metrics for TS assessment are proposed; they consist of two terms, the nodal and network topology metrics. The former models generator features just before a fault, whilst the second considers impact of a fault on units. The general problem is then decomposed into two stages, the first being economic dispatching and the second optimization of network topology for TS via developed network robustness metrics. The minimum cost topology solutions are ranked by the TS performance. The proposed approach is tested on the IEEE68 Bus test system and compared with time-domain TS results.

The increased uncertainty due to the integration of stochastic renewable energy sources necessitates solving Optimal Power Flow (OPF) problems repeatedly and with greater granularity. Machine learning methods hold significant potential to reduce the computing time for OPF problems by learning a mapping from varying input loads to decisions, thus bypassing the need for an optimization solver during inference. However, current machine learning methods for OPF lack interpretability and may produce infeasible decisions, which impedes their adoption by industry stakeholders. To this end, we propose a novel approach for interpretable learning of OPF solutions with feasibility guarantees. Specifically, we develop prescriptive decision trees that learn a piecewise affine mapping from input data to the solutions of a constrained optimization problem, using robust optimization to ensure that decisions are feasible. One important contribution of our work is the development of a tree-based learning method that utilizes non-orthogonal splits informed by domain knowledge, including network congestion and the merit order curve. By incorporating this information, we enhance both the interpretability and performance of the model. We further present a surrogate learning algorithm to handle large-scale problems. The proposed approach is evaluated on several test networks, up to 300 buses, under different types of uncertainty and operating conditions, and is compared to neural network-based models, which do not guarantee feasibility. Notably, our results demonstrate that interpretable, shallow prescriptive trees perform comparably to neural network-based models, which are considered the current state of the art. To the best of our knowledge, this work is the first to introduce an interpretable machine learning approach for directly learning OPF solutions.

AbstractBirding specialization can be measured alongside a continuum from the beginner to the specialist. The structure of birding specialization has three dimensions: (1) skill/knowledge, (2) behavior, and (3) psychological commitment. We tested the factorial structure and factorial invariance of the birding specialization scale in traditional and simplified Chinese, Finnish, German, Italian, Polish, Portuguese, and Spanish birders. A total of 2,913 (32% women) birdwatchers participated in this study. In all languages, the hierarchical factorial structure with three sub-factors and one general factor was satisfactory. We found support for configural invariance in all languages, metric invariance in some language comparisons, but no support for scalar invariance. Therefore, the construct can be applied in all languages, but comparisons of means should be done with caution. Further translation should try to seek the same configural invariance, but also aim for metric and scalar invariance.

THE BENEFITS OF implementing Lean manufacturing philosophy are higher throughput and elimination of the variation that can introduce defects into a process. In a static environment, implementing Lean philosophy creates [...]

A novel pulse-width modulation (PWM) architecture for all-digital transmitters (ADT) that achieves good in-band and out-band performance with a very low ratio between the modulated signal frequency and the carrier frequency is presented in this paper. The proposed scheme reduces the harmonics leaving only those corresponding to multiples of the carrier frequency, overcoming the spectral limitations of other PWM implementations and relaxing the filter requirements. The binary signal is obtained using a table-based approach with very low computational complexity, mapping the complex I/Q baseband signal to duty cycles of a square wave with low distortion. In addition, a new parallelized noise shaping circuit to reduce the distortion caused by the discretization of the duty-time intervals is presented. The digital radio frequency signal is generated using a high-speed serializer and a standard pulse former. The ADT is simulated under different scenarios to evaluate the influence of time resolution in terms of Adjacent Channel Power Ratio (ACPR) and Error Vector Magnitude (EVM). The transmitter performance is verified by an FPGA implementation using 64-QAM modulated signals, achieving values of ACPR1, ACPR2, and EVM better than −47 dBc, −53 dBc, and −35 dB, respectively, using 64 quantization levels for the PWM signal.

The health system in Chile is well developed, with broad national coverage. However, organizational limitations necessitate urgent structural reform due to a lack of resources and poor performance, with segmentation and inequity. The government's program for 2022-2026 proposes substantial reforms aimed at creating a universal health system. Other reform proposals formulated by various government programs and commissions, as well as think tanks, provide useful inputs to contextualize the government proposal. Different types of models coexist in the health system: public insurance is based on a social security model, the public system provides free care to the insured population, and private insurance and private care providers work on a market basis. The proposed system would function on the national health system model, combining a predominant national health service (Beveridge model) with a complementary social security system (Bismarck model), depending on the need for funding. With a focus on social project evaluation, the relevance (internal coherence and external alignment) and political and economic feasibility of the contents of the government program were reviewed. The proposal has internal coherence, but limited external alignment with the prevailing political and economic system, and little State capacity to increase the financing of public enterprises and their coverage. The contents of the proposal do not show sufficient facilitating conditions to reasonably suggest political and economic feasibility in terms of legal approval and effective implementation of the proposed reform. [ABSTRACT FROM AUTHOR]

In an attempt to speed up the solution of the unit commitment (UC) problem, both machine-learning and optimization-based methods have been proposed to lighten the full UC formulation by removing as many superfluous line-flow constraints as possible. While the elimination strategies based on machine learning are fast and typically delete more constraints, they may be over-optimistic and result in infeasible UC solutions. For their part, optimization-based methods seek to identify redundant constraints in the full UC formulation by exploring the feasibility region of an LP-relaxation. In doing so, these methods only get rid of line-flow constraints whose removal leaves the feasibility region of the original UC problem unchanged. In this paper, we propose a procedure to substantially increase the line-flow constraints that are filtered out by optimization-based methods without jeopardizing their appealing ability of preserving feasibility. Our approach is based on tightening the LP-relaxation that the optimization-based method uses with a valid inequality related to the objective function of the UC problem and hence, of an economic nature. The result is that the so strengthened optimization-based method identifies not only redundant line-flow constraints but also inactive ones, thus leading to more reduced UC formulations.

Conocer las características de la violencia de género que subyace entre los jóvenes en contextos de ocio, sus actitudes y cómo resuelven estos conflictos en los contextos de ocio donde consumen alcohol.

Despite the importance of both user and healthcare worker considerations to the achievement of a comprehensive understanding of dignified care in organizations, most studies in this regard have mainly considered patient aspects. This study aims to address this gap by designing and psychometrically validating a scale of organizational dignified treatment (ODT) toward healthcare workers. The sample consists of 442 healthcare workers from Colombia. We use a psychometric analytics framework comprising six processes that incorporate exploratory factor analysis, structural equation modeling, and machine learning methods. The final ODT scale contains six items and satisfies the requirements for reliability (Cronbach’s alpha, omega total, and composite reliability), goodness-of-fit, convergent and discriminant validity, equity (examining gender, age, education, and socioeconomic stratum using confirmatory factor analysis with control factors, differential item functioning, and satisficing analysis), criterion validity (considering healthcare worker well-being as the criterion), and predictive validity. Moreover, we identify and discuss six essential facets of ODT toward healthcare workers, namely, amiability, explained procedures, enjoyment in the workplace, security in the workplace, understandable information, and voice of healthcare workers.

ABSTRACTThis analysed the impact of high-press oriented rules during soccer small-sided games on players’ physical and physiological responses and to analyse whether integrating multiple informational constraints – rules – would increase the effect compared to the control game. Thirty-two U-20 elite soccer players engaged in this study. All players engaged in all the four conditions: control (no additional rules), 1-rule games (A, in which the defending team scores two points every time they regained the ball possession in their offensive midfield, and B, in which the attacking team scores two points every time they achieve a shot on goal in their offensive midfield), and 2-rules game (integrating both rules A and B) in random and balanced order. Physical and physiological variables were collected through a GPS device and a chest strap. A MANOVA was adopted to analyse the main effect of protocol on players’ responses. Results indicated that 1-rule games presented higher physical and physiological demands. In addition, high-press games elicited higher physiological and physical responses than free-play. Combining rules decreased the physical and physiological responses compared to applying the rules separately.

We develop a robust optimization framework for dynamic empty repositioning problems modeled using time-space networks. In such problems, uncertainty arises primarily from forecasts of future supplies and demands for assets [...]

In the era of antimicrobial resistance, the identification of new compounds with strong antimicrobial activity and the development of alternative therapies to fight drug-resistant bacteria are urgently needed. Here, we have used resveratrol, a safe and well-known plant-derived stilbene with poor antimicrobial properties, as a scaffold to design several new families of antimicrobials by adding different chemical entities at specific positions. We have characterized the mode of action of the most active compounds prepared and have examined their synergistic antibacterial activity in combination with traditional antibiotics. Some alkyl- and silyl-resveratrol derivatives show bactericidal activity against Gram-positive bacteria in the same low micromolar range of traditional antibiotics, with an original mechanism of action that combines membrane permeability activity with ionophore-related activities. No cross-resistance or antagonistic effect was observed with traditional antibiotics. Synergism was observed for some specific general-use antibiotics, such as aminoglycosides and cationic antimicrobial peptide antibiotics. No hemolytic activity was observed at the active concentrations or above, although some low toxicity against an MRC-5 cell line was noted.

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It's hard for Carmen Electra to remember a time when she wasn't intrigued by the opposite sex. 'I was always boy crazy,' admits Carmen, 36, who grew up in the [...]

Over the past two years, our favorite funny actress has faced some of the toughest personal and professional challenges in her life: heartbreak, divorce, Broadway on a broken foot. But [...]

Background: Vision depends on the interplay between photoreceptor cells of the neural retina and the underlying retinal pigment epithelium (RPE). Most genes involved in inherited retinal diseases display specific spatiotemporal expression within these interconnected retinal components through the local recruitment of cis-regulatory elements (CREs) in 3D nuclear space. Results: To understand the role of differential chromatin architecture in establishing tissue-specific expression at inherited retinal disease loci, we mapped genome-wide chromatin interactions using in situ Hi-C and H3K4me3 HiChIP on neural retina and RPE/choroid from human adult donor eyes. We observed chromatin looping between active promoters and 32,425 and 8060 candidate CREs in the neural retina and RPE/choroid, respectively. A comparative 3D genome analysis between these two retinal tissues revealed that 56% of 290 known inherited retinal disease genes were marked by differential chromatin interactions. One of these was ABCA4, which is implicated in the most common autosomal recessive inherited retinal disease. We zoomed in on retina- and RPE-specific cis-regulatory interactions at the ABCA4locus using high-resolution UMI-4C. Integration with bulk and single-cell epigenomic datasets and in vivo enhancer assays in zebrafish revealed tissue-specific CREs interacting with ABCA4. Conclusions: Through comparative 3D genome mapping, based on genome-wide, promoter-centric, and locus-specific assays of human neural retina and RPE, we have shown that gene regulation at key inherited retinal disease loci is likely mediated by tissue-specific chromatin interactions. These findings do not only provide insight into tissue-specific regulatory landscapes at retinal disease loci, but also delineate the search space for non-coding genomic variation underlying unsolved inherited retinal diseases. Graphical Abstract:

Abstract: Recently, it has been shown that a truncated HCV core (HCcAg) variant, covering the first 120 aa (HCcAg.120), interacts with plasmid DNA vaccine (pIDKE2), encoding the HCV structural proteins [...]

Minutes into a lively conversation over an early-morning breakfast of scrambled eggs and fruit, Tyra Banks, makeup-free and curled up beneath a turquoise shawl in the dressing room of her […]

Helen Hunt made two films while harboring a wonderful secret: She was pregnant with a long-awaited child. These days, the Oscar-winning actress can't keep quiet about her love for her [...]

When you're a Hollywood actress who has spent most of your career playing sex kittens, transitioning to more grownup roles can be a bitter pill to swallow. But for Heather [...]

LIKE TRACY AND HEPBURN, SAM AND DIANE. AND HARRY AND SALLY BEFORE THEM, DAVID DUCHOVNY AND TEA LEONI EXPRESS THEIR AFFECTION THROUGH GOOD-NATURED TEASING. Over lunch at a popular restaurant [...]

ABSTRACT. Many classes of drugs have been implicated in drug-induced lung diseases. The agents most commonly associated with bronchospasm are aspirin, NSAIDs, and nonselective β-blockers, while alveolar hemorrhage is most [...]

WE FIRST MET HER as a rebellious schoolgirl in an Aerosmith video, a twisted young temptress in the movie The Crush, and a bubbly valley girl in Clueless. Since then, [...]