Enriching Summer Work: An Evaluation of the Summer Career Exploration Program

To determine the impact of the Summer Career Exploration Program (SCEP), a privately funded summer jobs program for low-income teens, P/PV examined the lives of over 1700 applicants. These youth were randomly assigned to participate or to not participate in SCEP in the summer of 1999, and their outcomes were compared at four and twelve months after program application. Researchers found that implementation was strong, but program impacts were less impressive. While SCEPs participants got summer jobs at a substantially higher rate (92%) than the control group (62%), the programs ability to translate this large and immediate summer employment impact into intermediate gains (in terms of future plans, college enrollment, work success, sense of self-efficacy or reduced criminal activity) proved to be negligible. Although impacts were short lived, the report concludes that SCEP and similar programs have an important place in the larger mosaic of supports, programs and opportunities for young people

Reactive scheduling using a multi-agent model: the SCEP framework

Multi-agent systems have been successfully applied to the scheduling problem for some time. However, their use often leads to poorly unsatisfactory disappointing results. A new multi-agent model, called supervisor, customers, environment, producers (SCEP), is suggested in this paper. This model, developed for all types of planning activities, introduces a dialogue between two communities of agents leading to a high level of co-operation. Its two main interests are the following: first it provides a more efficient control of the consequences generated by the local decisions than usual systems to each agent, then the adopted architecture and behaviour permit an easy co-operation between the different SCEP models, which can represent different production functions such as manufacturing, supply management, maintenance or different workshops. As a consequence, the SCEP model can be adapted to a great variety of scheduling/planning problems. This model is applied to the basic scheduling problem of flexible manufacturing systems, andit permits a natural co-habitation between infinite capacity scheduling processes, performedby the manufacturing orders, and finite capacity scheduling processes, performed by the machines. It also provides a framework in order to react to the disturbances occurring at different levels of the workshop

A distributed multi-agent framework for shared resources scheduling

Nowadays, manufacturers have to share some of their resources with partners due to the competitive economic environment. The management of the availability periods of shared resources causes a problem because it is achieved by the scheduling systems which assume a local environment where all resources are on the same site. Therefore, distributed scheduling with shared resources is an important research topic in recent years. In this communication, we introduce the architecture and behavior of DSCEP framework (distributed, supervisor, customer, environment, and producer) under shared resources situation with disturbances. We are using a simple example of manufacturing system to illustrate the ability of DSCEP framework to solve the shared resources scheduling problem in complex systems

Online Admission Control and Embedding of Service Chains

The virtualization and softwarization of modern computer networks enables the definition and fast deployment of novel network services called service chains: sequences of virtualized network functions (e.g., firewalls, caches, traffic optimizers) through which traffic is routed between source and destination. This paper attends to the problem of admitting and embedding a maximum number of service chains, i.e., a maximum number of source-destination pairs which are routed via a sequence of to-be-allocated, capacitated network functions. We consider an Online variant of this maximum Service Chain Embedding Problem, short OSCEP, where requests arrive over time, in a worst-case manner. Our main contribution is a deterministic O(log L)-competitive online algorithm, under the assumption that capacities are at least logarithmic in L. We show that this is asymptotically optimal within the class of deterministic and randomized online algorithms. We also explore lower bounds for offline approximation algorithms, and prove that the offline problem is APX-hard for unit capacities and small L > 2, and even Poly-APX-hard in general, when there is no bound on L. These approximation lower bounds may be of independent interest, as they also extend to other problems such as Virtual Circuit Routing. Finally, we present an exact algorithm based on 0-1 programming, implying that the general offline SCEP is in NP and by the above hardness results it is NP-complete for constant L.Comment: early version of SIROCCO 2015 pape

Shared resources scheduling using a multi-agent model: the DSCEP framework

Recently, multi-agent systems have been successfully applied to the scheduling problem. A new multi- agent framework, called DSCEP (distributed, supervisor, customers, environment, producers), is suggested in this paper. This framework is developed base on the subsistent SCEP models, especial for shared resources scheduling activities. It introduces a dialogue between three kinds of evolved SCEP models leading to a high level of co-operation. It provides a more efficient control of the consequences generated by the local decisions than usual systems for each SCEP model. It also provides different algorithms in order to handle the disturbances occurring at different ranks in manufacturing process. As a consequence, the DSCEP framework can be adapted for various scheduling/planning problems. This model is applied to the shared resources scheduling problem of complex systems, and provide a natural cohabitation between infinite capacity scheduling processes, performed by the multi-site manufacturing orders, and finite capacity scheduling processes, performed by local or remote machines

Chemical defenses of the Caribbean sponges Agelas wiedenmayeri and Agelas conifera

Previous studies have determined that Caribbean reef sponges of the genus Agelas are chemically defended from fish predation by brominated pyrrole alkaloids, and that the compounds responsible for this defense have been elucidated for one species, Agelas clathrodes. In this study, we expand our understanding of chemical defense in this common sponge genus to include the characterization of defensive metabolites in the tissues of Agelas wiedenmayeri and Agelas conifera. Bioassay-directed isolation of defensive metabolites was undertaken using fish feeding assays carried out in laboratory aquaria and in the field. Agelas wiedenmayeri contained the same two major metabolites as Agelas clathrodes, 4,5-dibromopyrrole-2-carboxylic acid (1), and oroidin (2), in addition to a small amount of bromoageliferin (7). The two major metabolites were present at higher concentrations in samples of Agelas wiedenmayeri than in Agelas clathrodes, and their relative concentrations were reversed, with Agelas wiedenmayeri on average containing more 4,5-dibromopyrrole-2-carboxylic acid (1) (2.0 mg/mL) than oroidin (2) (0.8 mg/mL). Agelas conifera contained a mixture of dimeric bromopyrrole alkaloids dominated by sceptrin (3), with <10% each of dibromosceptrin (5), bromoageliferin (7), dibromoageliferin (8), ageliferin (6), and bromosceptrin (4). Mean concentration of sceptrin (3) in sponge tissue was 5.3 mg/mL; this compound deterred feeding of reef fish in aquarium assays at 1.0 mg/mL, the lowest concentration assayed. Sceptrin (3) concentrations were higher in sponges collected in the southern Bahama Islands than those collected in the middle Bahamas, but reasons for this variation remain unclear. The structure-activity relationship of the pyrrole group was investigated by assaying derivatives of the active metabolites. Feeding deterrent activity of the molecule was enhanced by the addition of bromine to the pyrrole group, but not affected by exchange of the heteroatom from N to O or S. Combining an understanding of the structure-activity relationship of Agelas metabolites with an understanding of the variation in these metabolites across the genus may provide insight into the evolution of defensive chemistry in this highly successful taxa of pan-tropical sponges

SINGLE-CELL ELECTROPORATION USING ELECTROLYTE-FILLED CAPILLARIES -EXPERIMENTAL AND MODELING INVESTIGATIONS

Electrolyte-filled capillaries (EFCs) with fine tips provide a highly concentrated electric field for local single-cell electroporation (SCEP) with high spatial resolution. A complete circuit for SCEP experiments was built that consisted of a test circuit and an electroporation circuit, with the ability to monitor electrically the electroporation pulses. SCEP itself was monitored in real time by observing the loss of a fluorescent adduct of glutathione (Thioglo-1-GSH) from the intracellular space. SCEP can be applied for transfection of individual adherent cells. We hypothesize that transfection of single cells can be accomplished with the plasmid contained in a single capillary. During SCEP, electroosmotic flow can pump electrolyte out of the capillary enhancing plasmid transfer into cells. This was confirmed from both simulation and transfection experiments. Cells were successfully transfected with EGFP-C2 plasmid when the loss of Thioglo-1-GSH upon SCEP (ΔF) is larger than 10% and its mass transfer rate (M) through the membrane exceeds 0.03 s-1. A series of SCEP experiments has been carried out on PC-3 cells (with 2-µm tip opening) and A549 cells (with 4~5-µm tip opening) to investigate how the parameters such as cell-to-tip distance (dc), cell size (dm) and shape, temperature, current, and the cell cycle affect SCEP outcomes (M and resealing rate α) via statistical analysis. A good linear regression is achieved only at a low temperature of 15℃. The main factors affecting small molecule transport across cell membrane are dc, dm and electric current. A range of M (0.03 s-1 ~ 0.4 s-1 for PC-3 cells, or 0.03 s-1 ~ 0.5 s-1 for A549 cells) gives the best linear regressions. M is also affected by the cell cycle of A549 cells, and correlated with cell roundness only for PC-3 cells. Cells reseal faster at higher temperature; while lower temperature provides better survivability with identical ΔF. Lastly, numerical models were elaborated as a platform for better understanding of the SCEP process and prediction of the trends of SCEP under various experimental conditions. A mass transport model involving potential distribution, diffusion, convection and electrokinetic flow was extended to study mass transport at a buffer-filled pipette tip/porous medium interface