A variable neighborhood search heuristic algorithm for the double vehicle routing problem with multiple stacks

This paper addresses the double vehicle routing problem with multiple stacks (DVRPMS) in which a fleet of vehicles must collect items in a pickup region and then travel to a delivery region where all items are delivered. The load compartment of all vehicles is divided into rows (horizontal stacks) of fixed profundity (horizontal heights), and on each row, the unloading process must respect the last‐in‐first‐out policy. The objective of the DVRPMS is to find optimal routes visiting all pickup and delivery points while ensuring the feasibility of the vehicle loading plans. We propose a new integer linear programming formulation, which was useful to find inconsistencies in the results of exact algorithms proposed in the literature, and a variable neighborhood search based algorithm that was able to find solutions with same or higher quality in shorter computational time for most instances when compared to the methods already present in the literature.     

A Spontaneous 3D Bone‐On‐a‐Chip for Bone Metastasis Study of Breast Cancer Cells

Bone metastasis occurs at ≈70% frequency in metastatic breast cancer. The mechanisms used by tumors to hijack the skeleton, promote bone metastases, and confer therapeutic resistance are poorly understood. This has led to the development of various bone models to investigate the interactions between cancer cells and host bone marrow cells and related physiological changes. However, it is challenging to perform bone studies due to the difficulty in periodic sampling. Herein, a bone‐on‐a‐chip (BC) is reported for spontaneous growth of a 3D, mineralized, collagenous bone tissue. Mature osteoblastic tissue of up to 85 µm thickness containing heavily mineralized collagen fibers naturally formed in 720 h without the aid of differentiation agents. Moreover, co‐culture of metastatic breast cancer cells is examined with osteoblastic tissues. The new bone‐on‐a‐chip design not only increases experimental throughput by miniaturization, but also maximizes the chances of cancer cell interaction with bone matrix of a concentrated surface area and facilitates easy, frequent observation. As a result, unique hallmarks of breast cancer bone colonization, previously confirmed only in vivo, are observed. The spontaneous 3D BC keeps the promise as a physiologically relevant model for the in vitro study of breast cancer bone metastasis.     

Nitrous oxide emissions from enhanced-efficiency nitrogen fertilizers applied to annual crops in a subtropical ecosystem

Nutrient Cycling in Agroecosystems - In this study, we assessed the potential of enhanced-efficiency nitrogen (EEN) fertilizers for mitigating nitrous oxide (N2O) emissions and compared it with...     

Data Plane Programmability Beyond OpenFlow: Opportunities and Challenges for Network and Service Operations and Management

SDN and OpenFlow reshaped the way we configure forwarding devices and determine network behavior, by offering an open interface upon which apps like routing, monitoring, etc. can be built. SDN/OpenFlow helped break network “ossification” and unleash evolution, by enabling one to effectively think networking from top-down. It evidenced, however, a subtle but important problem: networking evolution is also hampered by the inability to change switch behavior, which forces one to build systems constrained from the bottom up. This scenario can change dramatically with the re-emergence of programmable data planes, and languages like POF and P4. Although recent, these languages proved to be very influential, powering several contributions towards flexible and customizable forwarding devices. In this paper, we survey the literature on data plane programmability, from early concepts (like Active Networks) to state-of-the-art solutions. We then dive into research questions that more recent work (especially P4) have uncovered: how to deploy and manage custom switch programs in large-scale networks? Can we improve services like monitoring and security with programmable data planes? Can we make network operation more dependable? As another contribution, we organize and discuss opportunities and challenges with potential to influence research in the field, from the perspective of network and service operations and management.     

<Emphasis Type="Italic">Bidens pilosa</Emphasis> L. Exhibits High Sensitivity to Coumarin in Comparison with Three Other Weed Species

Nine natural plant compounds were screened for phytotoxicity to Bidens pilosa L. a troublesome weed in field and plantation crops. The sensitivity of three other weed species to coumarin, the most active identified compound, was also evaluated. Coumarin, at a concentration of 500 μM, had little effect on germination and growth of Senna obtusifolia L., Euphorbia heterophylla L., and Ipomoea grandifolia L. when compared with its effects on B. pilosa L. In a concentration range of 10–100 μM, coumarin caused a dose-dependent inhibition of germination and growth of B. pilosa L. The measurements of some parameters of energy metabolism revealed that coumarin-treated root tissues exhibited characteristics of seedlings in an earlier stage of growth, including higher respiratory activity and higher activities of alcohol dehydrogenase and lipoxygenase. These results suggest that coumarin inhibition of germination and growth of B. pilosa L. was not a consequence of an impairment of energy metabolism. Rather, it seems to act as a cytostatic agent, retarding germination. At concentrations above 50 μM, coumarin increased lipoxygenase activity and the level of conjugated dienes of root extracts, suggesting that it may induce oxidative stress in seedling roots.     

Virtual Harlem [learning environment]

The paper discusses Virtual Harlem, a learning environment that lets students experience the Harlem Renaissance of the 1920s and 1930s as a cultural field trip. Virtual Harlem is a collaborative virtual reality (VR) tour of Harlem in which participants can travel back 80 years to see and hear historical figures, speeches, and music from that period     

Synthesis and characterization of manganese oxide-doped dicalcium silicates obtained from rice hull ash

This work describes the synthesis and hydration behavior of dicalcium silicates doped with manganese. The syntheses were performed using silica obtained from rice hull ash. The solids (SiO₂, CaO and MnO) were weighed in stoichiometric proportions to prepare silicates having a ratio (Ca + Mn)/Si = 2. Insertion of manganese varied from 1 to 10% (mol). Solids were grounded and water was added rendering aqueous suspensions. The suspensions were sonicated for 60 min in an ultrasonic bath. After drying, the resulting solids were grounded and burned at 800 °C. The preparation of calcium silicates containing up to 10% of manganese oxide was observed.Hydration degree of a dicalcium silicate and calcium silicate containing 5% of manganese was determined by thermal analysis. Both materials present similar behavior. Hydration degree reaches approximately 70% after 60 days.     

Calcium silicate cements obtained from rice hull ash: A comparative study

This work describes the utilization of rice hull as raw-material for the preparation of two calcium silicates namely, β-Ca_1.91Ba_0.04SiO₄ and β-Ca_1.96Ba_0.04SiO₄. The synthesis was completed at 800°C. Hydration rate and compressive strength of mortars prepared with the two calcium silicates were studied and compared to mortars prepared with commercial Portland cement. Hydration rates for both silicates, studied by thermogravimetric and FTIR analysis are very similar; after 60 days the hydration rates are around 42–43% and reaches 75% after 270 days. Compressive strength experiments were performed using test specimen prepared with commercial Portland cement as reference, and blends of Portland cement and the two calcium silicates, at replacement levels of 10 and 20%. Results have shown that after a 90 days curing period, the compressive strength of the reference and the blends containing 10% of each of the calcium silicates show the same behavior. Using a replacement level of 20% there is a small decrease in compressive strength. This behavior is attributed to the lower hydration rate of these calcium silicates.