Vulnerability Assessment and Re-routing of Freight Trains Under Disruptions: A Coal Supply Chain Network Application

In this paper, we present a two-stage mixed integer programming (MIP) interdiction model in which an interdictor chooses a limited amount of elements to attack first on a given network, and then an operator dispatches trains through the residual network. Our MIP model explicitly incorporates discrete unit flows of trains on the rail network with time-variant capacities. A real coal rail transportation network is used in order to generate scenarios to provide tactical and operational level vulnerability assessment analysis including rerouting decisions, travel and delay costs analysis, and the frequency of interdictions of facilities for the dynamic rail system

Analysis of efficiency and profitability of franchise services

The present study analyses the relative efficiency of franchise services and characterises the best companies, confirming the relationship between efficiency and profit. These companies are from the trade and other services sector , the main group of service-providing companies in the Spanish economy. The methodology calls for first comparing the relative efficiency of franchisers and ownership enterprises. Second, the focus turns to the most efficient franchise services, using a super-efficiency model to rank them. The paper then goes on to cover the analysis of the main characteristics of the best franchise enterprises, the number of own establishments in a franchise business and the profitability of the company. This paper presents arguments as to why companies from the trade and other services sector are included. The main conclusion is that, whilst the number of establishments is irrelevant in achieving greater efficiency, many of the most efficient enterprises have high returns.García Martin, CJ.; Medal Bartual, A.; Peris-Ortiz, M. (2014). Analysis of efficiency and profitability of franchise services. Service Industries Journal. 34(9):796-810. doi:10.1080/02642069.2014.905921S79681034

Gratiana boliviana (Coleoptera: Chrysomelidae) does not feed on Jamaican nightshade Solanum jamaicense (Solanaceae)

Jamaican nightshade has been in Florida for at least 77 years, but is considered rare and only found in 4 counties in the central peninsula. However, there are many examples of long lag periods between the time an exotic plant arrives at a new location, and the time it spreads and becomes highly invasive (Sakai et al. 2001). Locally dense populations of Jamaican nightshade in hammock areas in Saint Lucie and Osceola counties suggest that the plant is adapted to at least some habitats in Florida, and could eventually spread to similar habitats and become a serious exotic invader. The current study demonstrated that G. boliviana, a biological control agent established in Florida for control of tropical soda apple, does not utilize Jamaican nightshade for feeding or oviposition. If Jamaican nightshade becomes a more serious invasive weed in the future, it may be possible to identify host specific natural enemies from its native range

The effect of Gratiana boliviana (Coleoptera: Chrysomelidae) herbivory on growth and population density of tropical soda apple (Solanum viarum) in Florida

The effect of herbivory by Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) on the invasive, tropical soda apple (TSA) (Solanum viarum Dunal, Solanaceae), was investigated using exclusion methods and by monitoring the density of G. boliviana and the weed at four locations over a period of 40 months. TSA plants protected by insecticide were taller, wider, and had greater canopy cover that unprotected plants, and plants in closed cages were taller and wider than those in open cages. Survival of plants was higher in plots protected with insecticide than in unprotected plots in both years of a 2-year study. In the population dynamics study, the initial density of TSA was 4-5 times higher at one of the locations than at the other three sites, but within 3 years, TSA density at the high density site had declined by 90%. At the three sites which initially had a low abundance of TSA, density remained low throughout the study. The intrinsic rate of increase of G. boliviana varied between -3.9 and 4.5, but over the 3-year study, was not different from zero, indicating a stable population. The intrinsic rate of increase was lower than zero for the period from October to January, and greater than zero during the January to April period. In the periods from April to July and July to October, the rate of increase was not different from zero. The implications of these results for biological control of TSA in Florida are discussed. © 2010 Taylor & Francis

Host specificity tests of Gratiana graminea (Coleoptera: Chrysomelidae), a potential biological control agent of tropical soda apple, Solanum viarum (Solanaceae)

Multiple-choice and no-choice tests were conducted at the Department of Agriculture, Division of Plant Industry Quarantine facility in Gainesville, FL to determine the specificity of the Brazilian leaf-beetle Gratiana graminea Klug, a candidate for biological control of Solanum viarum, tropical soda apple. One hundred fifteen plant species in 32 families were included in the feeding-oviposition multiple-choice tests including the target weed and the 5 major cultivated Solanaceae Capsicum annuum L., Lycopersicon sculentum Mill., Nicotiana tabacum L., Solanum melongena L., and Solanum tuberosum L. Eight to 12 plant species, including always the main target weed, growing in 1-gallon pots were simultaneously exposed to 20 G. graminea adults (10 males and 10 females that most of the time had recently emerged from pupae) in an aluminum cage (60 × 60 × 60 cm). At the beginning of each test the insects were placed at the bottom center of each cage to allow them to orient by themselves to the tested plants. Plant species in each test were replicated 34 times (one replication of tested plants in each separate cage). Plants tested were exposed to G. graminea adults from 36 weeks. Observation of oviposition and feeding were made during almost all the weekdays. No-choice host specificity tests were conducted with G. graminea adults on potted plants in cages made of clear-plastic cylinders and with G. graminea larvae placed on cluster of leaves of each individual plant tested. Ten G. graminea adults were exposed to 29 plant species individually tested during 3 to 5 weeks, and 10 neonate larvae were exposed to 31 plant species. Plant species in each test were replicated 34 times. Results indicated that G. graminea fed and developed only on the target weed. The tests indicated that a host range expansion of G. graminea to any of the major cultivated Solanaceae species is highly unlikely. A petition for field release in Florida was submitted to the Technical Advisory Group for Biological Control Agents of Weeds (TAG) in Sep 2008

An exploratory insect survey of tropical soda apple in Brazil and Paraguay

An exploratory survey was conducted in Brazil and Paraguay to record insects feeding on Solanum viarum Dunal (Solanaceae). A list of insects collected is included. The survey indicated that a diverse group of phytophagous insects is associated with S. viarum, and some of them may have potential as biocontrol agents of S. viarum in Florida

Host specificity of Anthonomus tenebrosus (Coleoptera: Curculionidae), a potential biological control agent of tropical soda apple (Solanaceae) in Florida

Multiple-choice and no-choice tests were conducted at the Florida Department of Agriculture quarantine facility to determine the host specificity of the South American flower bud weevil, Anthonomus tenebrosus Boheman, intended for biological control of the exotic weed tropical soda apple (TSA), Solanum viarum Dunal in Florida, USA. Ninety-one plant species in 21 families were included in multiple-choice feeding and oviposition experiments, including the target weed and the 6 major cultivated Solanaceae: bell pepper (Capsicum annuum L.), chili pepper (C. frutescens L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.), eggplant (Solanum melongena L.), and potato (Solanum tuberosum L.). Plant bouquets with flower-buds of 8 to 10 randomly selected plant species, always including TSA (S. viarum) were exposed to 10-20 A. tenebrosus adults for 1 to 2 weeks. Oviposition and feeding were observed twice a week. No-choice host-specificity tests were also conducted with A. tenebrosus adults using potted flowering plants. Ten adults were exposed to 29 plant species individually tested for 1 to 2 weeks. Plant species in each test were replicated 3 or 4 times. All tests showed that A. tenebrosus fed and laid eggs only on the target weed. No eggs were deposited on any of the other of the 91 plant species tested. Host-specificity tests indicated that a host range expansion of A. tenebrosus to include any of the crops, and native Solanaceae, and non-solanaceous plants tested is highly unlikely. A petition for field release in the USA was submitted to the Technical Advisory Group for Biological Control Agents of Weeds (TAG) in Oct 2007