1,385 research outputs found
A Redesigned Benders Decomposition Approach for Large-Scale In-Transit Freight Consolidation Operations
The growth in online shopping and third party logistics has caused a revival
of interest in finding optimal solutions to the large scale in-transit freight
consolidation problem. Given the shipment date, size, origin, destination, and
due dates of multiple shipments distributed over space and time, the problem
requires determining when to consolidate some of these shipments into one
shipment at an intermediate consolidation point so as to minimize shipping
costs while satisfying the due date constraints. In this paper, we develop a
mixed-integer programming formulation for a multi-period freight consolidation
problem that involves multiple products, suppliers, and potential consolidation
points. Benders decomposition is then used to replace a large number of integer
freight-consolidation variables by a small number of continuous variables that
reduces the size of the problem without impacting optimality. Our results show
that Benders decomposition provides a significant scale-up in the performance
of the solver. We demonstrate our approach using a large-scale case with more
than 27.5 million variables and 9.2 million constraints
Validation of the organizational justice scale in a portuguese context
This article presents a Portuguese translation and cultural modification of
the Organizational Justice Scale of Niehoff and Moorman (1993). The scale
was tested in two correlational studies, one with 115 employees from the
technical staff of a Portuguese organization and a second with 59 Portuguese
teachers, testing the scale’s discriminant validity through comparison with
other measures such as psychological contract violation, organizational
identification, work motivation, job satisfaction and perceived ability–job fit.
The scale showed satisfying consistency and in a factorial analysis of the
Portuguese version; the item distribution per factor was the same as that of
the original scale (Niehoff & Moorman, 1993). The Portuguese Organizational
Justice scale showed adequate reliability and validity. Therefore, this
Portuguese version can be considered a suitable instrument to assess organizational
justice among the Portuguese population.info:eu-repo/semantics/acceptedVersio
Educación Musical Escolar en las Américas: Condiciones, Prácticas, y PolÃticas desde una Perspectiva Socio-Ecológica
La educación musical formal está presente en un gran número de escuelas primarias y secundarias a lo largo de las Américas, aunque tanto las polÃticas educativas, planes de estudios y su implementación varÃan según regiones, estados e instituciones educativas. El conocimiento de las condiciones actuales de la educación musical en un hemisferio, cada vez más interconectado e interdependiente, podrÃa ofrecer ideas para resolver desafÃos de acceso, igualdad, y equidad hacia una educación artÃstica de calidad. Este artÃculo ha sido escrito para proporcionar una sintaxis general, no exhaustiva, de la investigación sobre programas y polÃticas de música escolar a lo largo de las Américas. Más especÃficamente, dentro de un marco socioeconómico, hemos tratado de determinar de qué manera factores externos afectan las prácticas docentes asà como el impacto de los docentes de aula en estas fuerzas. Se espera que esta examinación ofrezca ideas a quienes elaboran y promueven polÃticas educativas en artes, para asegurar que los estudiantes tengan igualdad de oportunidades y acceso a una educación musical escolar de calidad
Distribution of phytoplankton pigments in nine European estuaries and implications for an estuarine typology
Phytoplankton pigments were studied by LiquidChromatography (HPLC) in nine West Europeanestuaries. Three estuaries, i.e. the Rhine,Scheldt and the Gironde were sampled four timesto cover the different seasons, whereas theother six estuaries were sampled once. Pigmentdistributions in estuaries reflect bothriverine inputs as well as autochthonousblooms. Fucoxanthin was the most commonaccessory photosynthetic pigment showing thatDiatoms were the most common group in thestudied estuaries and were particularlydominant during autumn and winter. In the veryturbid Gironde estuary, degradation processeswere predominant between salinities 1 and 20,while Diatoms, Dinoflagellates and Cryptophytesbloomed above 20 salinity during spring andsummer. This contrasted with the highlyeutrophic but less turbid Scheldt, wherephytoplanktonic blooms occurred at lowsalinities close to the city of Antwerp. In theScheldt, we observed both a tenfold fluctuationof phytoplankton biomass and a fluctuatingpigment diversity index. In contrast,chlorophyll a was always low in theGironde, but we observed large variations ofpigment diversity among samplings duringdifferent seasons. Distribution of pheopigmentsshowed that the maximum turbidity zone (MTZ)was a highly reactive region for heterotrophicphytoplankton degradation. The Scheldt and theThames were the most anthropogenic influencedestuaries contrasting with the Gironde estuarythat has a less urbanised watershed. Anestuarine typology is proposed based on threeclusters emerging from a correspondenceanalysis of pigment variables and variablescharacterising the anthropogenic impact andphysical forcing
A bioprinted 3D gut model with crypt-villus structures to mimic the intestinal epithelial-stromal microenvironment
The intestine is a complex tissue with a characteristic three-dimensional (3D) crypt-villus architecture, which plays a key role in the intestinal function. This function is also regulated by the intestinal stroma that actively supports the intestinal epithelium, maintaining the homeostasis of the tissue. Efforts to account for the 3D complex structure of the intestinal tissue have been focused mainly in mimicking the epithelial barrier, while solutions to include the stromal compartment are scarce and unpractical to be used in routine experiments. Here we demonstrate that by employing an optimized bioink formulation and the suitable printing parameters it is possible to produce fibroblast-laden crypt-villus structures by means of digital light projection stereolithography (DLP-SLA). This process provides excellent cell viability, accurate spatial resolution, and high printing throughput, resulting in a robust biofabrication approach that yields functional gut mucosa tissues compatible with conventional testing techniques.Copyright © 2023 Elsevier B.V. All rights reserved
Middle Ordovician harknessellid brachiopods (Dalmanellidina) from the Mediterranean margin of Gondwana
The family Harknessellidae Bancroft, 1928 (Orthida, Dalmanellidina) was designed to embrace an assemblage of species referred previously to Harknessella Reed, 1917, and included five genera known mainly from the Middle and Upper Ordovician of England. Herein, we suggest reassigning to this family the genus Cacemia Mitchell, 1974, widespread in the middle Darriwilian (upper Middle Ordovician) of the Iberian and Armorican massifs. Since its designation, Cacemia was placed among the dalmanellidin heterorthids, in spite of its strongly mucronate hinge line, which is totally unknown within this Mediterranean family. A new harknessellid has been identified from the upper Darriwilian beds of the Central Iberian Zone (Central Spain): Isabelella fascicostellata Reyes-Abril Villas gen. et sp. nov. It is similar to Horderleyella Bancroft, 1928 for its coarsely fascicostellate radial ornamentation and obtuse cardinal angles, although its convexoplane to convexoconcave profile allows discrimination from the typically dorsibiconvex Horderleyella. A phylogenetic analysis of the family places both Cacemia and Isabelella in basal positions of their clades, which fits with their early stratigraphic record. Based on our study, the family Harknessellidae appears to have originated in the high latitude Mediterranean margins of Gondwana during pre-Darriwilian times, before the detachment of Avalonia from Gondwana. The family reached its highest diversification in Avalonia throughout the Late Ordovician, keeping connections with the Mediterranean and Proto-Andean margins of Gondwana, as well as with the mid-latitude palaeocontinents of Baltica and South China.Peer Reviewe
Computational Fluid Dynamics simulations of the Late Pleistocene Lake Bonneville Flood
At approximately 18.0 ka, pluvial Lake Bonneville reached its maximum level. At its northeastern extent it was impounded by alluvium of the Marsh Creek Fan, which breached at some point north of Red Rock Pass (Idaho), leading to one of the largest floods on Earth. About 5320 km3 of water was discharged into the Snake River drainage and ultimately into the Columbia River. We use a 0D model and a 2D non-linear depth-averaged hydrodynamic model to aid understanding of outflow dynamics, specifically evaluating controls on the amount of water exiting the Lake Bonneville basin exerted by the Red Rock Pass outlet lithology and geometry as well as those imposed by the internal lake geometry of the Bonneville basin. These models are based on field evidence of prominent lake levels, hypsometry and terrain elevations corrected for post-flood isostatic deformation of the lake basin, as well as reconstructions of the topography at the outlet for both the initial and final stages of the flood. Internal flow dynamics in the northern Lake Bonneville basin during the flood were affected by the narrow passages separating the Cache Valley from the main body of Lake Bonneville. This constriction imposed a water-level drop of up to 2.7 m at the time of peak-flow conditions and likely reduced the peak discharge at the lake outlet by about 6%. The modeled peak outlet flow is 0.85·106 m3 s−1. Energy balance calculations give an estimate for the erodibility coefficient for the alluvial Marsh Creek divide of ∼0.005 m y−1 Pa−1.5, at least two orders of magnitude greater than for the underlying bedrock at the outlet. Computing quasi steady-state water flows, water elevations, water currents and shear stresses as a function of the water-level drop in the lake and for the sequential stages of erosion in the outlet gives estimates of the incision rates and an estimate of the outflow hydrograph during the Bonneville Flood: About 18 days would have been required for the outflow to grow from 10% to 100% of its peak value. At the time of peak flow, about 10% of the lake volume would have already exited; eroding about 1 km3 of alluvium from the outlet, and the lake level would have dropped by about 10.6 m
Middle Ordovician harknessellid brachiopods (Dalmanellidina) from the Mediterranean margin of Gondwana
The family Harknessellidae Bancroft, 1928 (Orthida, Dalmanellidina) was designed to embrace an assemblage of species referred previously to Harknessella Reed, 1917, and included five genera known mainly from the Middle and Upper Ordovician of England. Herein, we suggest reassigning to this family the genus Cacemia Mitchell, 1974, widespread in the middle Darriwilian (upper Middle Ordovician) of the Iberian and Armorican massifs. Since its designation, Cacemia was placed among the dalmanellidin heterorthids, in spite of its strongly mucronate hinge line, which is totally unknown within this Mediterranean family. A new harknessellid has been identified from the upper Darriwilian beds of the Central Iberian Zone (Central Spain): Isabelella fascicostellata Reyes-Abril Villas gen. et sp. nov. It is similar to Horderleyella Bancroft, 1928 for its coarsely fascicostellate radial ornamentation and obtuse cardinal angles, although its convexoplane to convexoconcave profile allows discrimination from the typically dorsibiconvex Horderleyella. A phylogenetic analysis of the family places both Cacemia and Isabelella in basal positions of their clades, which fits with their early stratigraphic record. Based on our study, the family Harknessellidae appears to have originated in the high latitude Mediterranean margins of Gondwana during pre-Darriwilian times, before the detachment of Avalonia from Gondwana. The family reached its highest diversification in Avalonia throughout the Late Ordovician, keeping connections with the Mediterranean and Proto-Andean margins of Gondwana, as well as with the mid-latitude palaeocontinents of Baltica and South China
Surgical treatment of type 2 giant mesenteric cyst: case report and literature review
Mesenteric lesions, including cysts, are rare abdominal tumours and in most cases non-neoplastic. They may have an asymptomatic course or present with pain, abdominal distension or intestinal obstruction. The suggested management is surgical resection of the lesions by laparotomy or minimally invasive surgery. We presented the case of a 48-year-old patient with progressive abdominal distension attributed to liver cirrhosis. Ultrasound and computed tomography of the abdomen showed evidence of a giant cyst of the mesentery with no evidence of tumor activity. We therefore decided to perform an exploratory laparotomy with cystectomy and omentectomy, follow-up and pathology report negative for malignancy
Bose-Einstein condensate dark matter phase transition from finite temperature symmetry breaking of Klein-Gordon fields
In this paper the thermal evolution of scalar field dark matter particles at
finite cosmological temperatures is studied. Starting with a real scalar field
in a thermal bath and using the one loop quantum corrections potential, we
rewrite Klein-Gordon's (KG) equation in its hydrodynamical representation and
study the phase transition of this scalar field due to a Z_2 symmetry breaking
of its potential. A very general version of a nonlinear Schr\"odinger equation
is obtained. When introducing Madelung's representation, the continuity and
momentum equations for a non-ideal SFDM fluid are formulated, and the
cosmological scenario with the SFDM described in analogy to an imperfect fluid
is then considered where dissipative contributions are obtained in a natural
way.Additional terms appear compared to those obtained in the classical version
commonly used to describe the \LambdaCDM model, i.e., the ideal fluid. The
equations and parameters that characterize the physical properties of the
system such as its energy, momentum and viscous flow are related to the
temperature of the system, scale factor, Hubble's expansion parameter and the
matter energy density. Finally, some details on how galaxy halos and smaller
structures might be able to form by condensation of this SF are given.Comment: Substantial changes have been made to the paper, following the
referees recommendations. 16 pages. Published in Classical and Quantum
Gravit
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