Small cosmological constants in string theory

We construct supersymmetric AdS4 vacua of type IIB string theory in compactifications on orientifolds of Calabi-Yau threefold hypersurfaces. We first find explicit orientifolds and quantized fluxes for which the superpotential takes the form proposed by Kachru, Kallosh, Linde, and Trivedi. Given very mild assumptions on the numerical values of the Pfaffians, these compactifications admit vacua in which all moduli are stabilized at weak string coupling. By computing high-degree Gopakumar-Vafa invariants we give strong evidence that the α′ expansion is likewise well-controlled. We find extremely small cosmological constants, with magnitude < 10−123 in Planck units. The compactifications are large, but not exponentially so, and hence these vacua manifest hierarchical scale-separation, with the AdS length exceeding the Kaluza-Klein length by a factor of a googol.

COVID-19 and public transport demand trends in Sicily: analyzing external factors and governmental recommendations

The year 2020 has brought changes in transport services and travel demand globally due to restrictions related to the spread of the COVID-19 pandemic, especially in public transport. The present work focuses on Sicily (Southern Italy). Through the elaboration and administration of an online questionnaire, a sample of 700 regular public transport users was characterized from a socio-demographic point of view, identifying their travel habits, and their opinion on governmental and public transport company initiatives. Eight (8) national government strategies were evaluated on a Likert scale, and ten (10) pandemic mitigation factors were assessed in different phases of the pandemic, highlighting which of these factors were most preferred by the sample on a hierarchical scale. The results lay the groundwork for identifying critical challenges when dealing with such severely restricted mobility conditions and suggesting improvements for public transport agencies and local authorities.

Elongated Small Object Detection from Remote Sensing Images Using Hierarchical Scale-Sensitive Networks

The detection of elongated objects, such as ships, from satellite images has very important application prospects in marine transportation, shipping management, and many other scenarios. At present, the research of general object detection using neural networks has made significant progress. However, in the context of ship detection from remote sensing images, due to the elongated shape of ship structure and the wide variety of ship size, the detection accuracy is often unsatisfactory. In particular, the detection accuracy of small-scale ships is much lower than that of the large-scale ones. To this end, in this paper, we propose a hierarchical scale sensitive CenterNet (HSSCenterNet) for ship detection from remote sensing images. HSSCenterNet adopts a multi-task learning strategy. First, it presents a dual-direction vector to represent the posture or direction of the tilted bounding box, and employs a two-layer network to predict the dual direction vector, which improves the detection block of CenterNet, and cultivates the ability of detecting targets with tilted posture. Second, it divides the full-scale detection task into three parallel sub-tasks for large-scale, medium-scale, and small-scale ship detection, respectively, and obtains the final results with non-maximum suppression. Experimental results show that, HSSCenterNet achieves a significant improved performance in detecting small-scale ship targets while maintaining a high performance at medium and large scales.

Women and glass ceilings in the construction industry: a review

ABSTRACT At the global level, the representation of men and women in the hierarchical scale within the labor market manifests itself unevenly, generally concentrating the occupations of women in the lower scales. An explanation for this phenomenon is the glass ceilings, invisible barriers faced by women during the development of their careers, which do not allow them to progress towards higher positions. This phenomenon is not indifferent to the construction sector, where a relatively unknown situation is observed for women; This situation has prompted a series of investigations with the shared concern to identify the obstacles that prevent women from developing in the construction sector. This article carries out a bibliographic review of the subject using the technique of documentary analysis, which has made it possible to obtain the state of the art and identify the dimensions that make up glass ceilings in the construction sector. The results point to the presence and constancy of glass ceilings due to the nature of the sector, the walls that begin in the hiring activity and persist throughout all professional development; thus, perpetuating inequalities between women and men from one generation to another within the sector. RESUMEN A nivel mundial, la representación de hombres y mujeres en la escala jerárquica dentro del mercado laboral se manifiesta de forma desigual, concentrando generalmente las ocupaciones de las mujeres en las escalas inferiores. Una explicación de este fenómeno son los techos de cristal, barreras invisibles a las que se enfrentan las mujeres durante el desarrollo de sus carreras, que no les permiten progresar hacia posiciones más altas. Este fenómeno no es indiferente al sector de la construcción, donde se observa una situación relativamente desconocida para las mujeres; esta situación ha impulsado una serie de investigaciones con la preocupación compartida de identificar los obstáculos que impiden a las mujeres desarrollarse en el sector de la construcción. En este artículo se realiza una revisión bibliográfica del tema mediante la técnica del análisis documental, que ha permitido obtener el estado del arte e identificar las dimensiones que conforman los techos de cristal en el sector de la construcción. Los resultados apuntan a la presencia y constancia de los techos de cristal debido a la naturaleza del sector, muros que se inician en la actividad de contratación y persisten a lo largo de todo el desarrollo profesional; perpetuando así las desigualdades entre mujeres y hombres de una generación a otra dentro del sector.

Hierarchical scaling within the spaces Syntax of the Mosulian house

Hierarchical Scaling is one of the Architectural Engineering principles. this principle isdetermined by the apparent scales within the basic elements of architectural design and the nature of thehierarchy in its dimensions. This principle was discussed in previous studies in terms of its relation tonature, its types in different levels of architecture and city.The property of the hierarchical scale wasdiscussed in the previous knowledge in terms of its relation to nature, its types and its general bases at thelevel of architecture and city. Therefore, the need to study this principle appeared at the level of house layoutthrough studying its space syntax in different time periods and its reflection on several aspects.Thus, theresearch problem was determined by "the need to explore the levels of the hierarchical scale within thespace syntax of the houses especially Mosulian house, and its variation within different time periods."The research adopted the quantitative approach consisting of three steps, after introducing generalknowledge base of the concept of the hierarchical scale and the studies that dealt with it in architecture, first:building a theoretical framework on the vocabulary associated with measuring the spatial hierarchical scalewithin the space syntax, second: conducting a practical study on an elected group of Mosulian houses withinfour periods, (20 houses distributed through, traditional, traditional-heritage, transitional andcontemporary),third: analysis of results and identification of conclusions.The research found that theMosulian houses within (the traditional -heritage period) was distinguished by its having a deep spatialhierarchical scale, unlike the Mosulian houses (with a transitional period) that entails many indicators at thelevel of the social dimension in achieving social isolation.

Compositional turnover in ecto- and endoparasite assemblages of an African bat, Miniopterus natalensis (Chiroptera, Miniopteridae): effects of hierarchical scale and host sex

We studied the compositional turnover in infracommunities and component communities of ecto- and endoparasites infesting a bat, Miniopterus natalensis (Chiroptera, Miniopteridae), across seven sampling sites using the zeta diversity metric (measuring similarity between multiple communities) and calculating zeta decline and retention rate (both scales) and zeta decay (component communities). We asked whether the patterns of zeta diversity differ between (a) infracommunities and component communities; (b) ecto- and endoparasites and (c) subsets of communities infecting male and female bats. The pattern of compositional turnover differed between infracommunities and component communities in endoparasites only. The shape of zeta decline for infracommunities indicated that there were approximately equal probabilities of ecto- and endoparasitic species to occur on/in any bat individual within a site. The shape of zeta decline for component communities suggested the stochasticity of ectoparasite turnover, whereas the turnover of endoparasites was driven by niche-based processes. Compositional turnover in component communities of ectoparasites was more spatially dependent than that of endoparasites. Spatial independence of compositional turnover in endoparasites was due to subcommunities harboured by female bats. We conclude that the patterns of compositional turnover in infracommunities were similar in ecto- and endoparasites, whereas the patterns of turnover in component communities differed between these groups.

Mean first passage time on a family of weighted directed hierarchical scale-free networks

Random walks on binary scale-free networks have been widely studied. However, many networks in real life are weighted and directed, the dynamic processes of which are less understood. In this paper, we firstly present a family of directed weighted hierarchical scale-free networks, which is obtained by introducing a weight parameter [Formula: see text] into the binary (1, 3)-flowers. Besides, each pair of nodes is linked by two edges with opposite direction. Secondly, we deduce the mean first passage time (MFPT) with a given target as a measure of trapping efficiency. The exact expression of the MFPT shows that both its prefactor and its leading behavior are dependent on the weight parameter [Formula: see text]. In more detail, the MFPT can grow sublinearly, linearly and superlinearly with varied [Formula: see text]. Last but not least, we introduce a delay parameter p to modify the transition probability governing random walk. Under this new scenario, we also derive the exact solution of the MFPT with the given target, the result of which illustrates that the delay parameter p can only change the coefficient of the MFPT and leave the leading behavior of MFPT unchanged. Both the analytical solutions of MFPT in two distinct scenarios mentioned above agree well with the corresponding numerical solutions. The analytical results imply that we can get desired transport efficiency by tuning weight parameter [Formula: see text] and delay parameter p. This work may help to advance the understanding of random walks in general directed weighted scale-free networks.