Cost-effective upgrade of WDM all-optical networks using overlay fibres and hop reduction links

Fibre overlay is a cost-effective technique to alleviate wavelength blocking in some links of a wavelength-routed optical network by increasing the number of wavelengths in those links. In this letter, we investigate the effects of overlaying fibre in an all-optical network (AON) based on GÉANT2 topology. The constraint-based routing and wavelength assignment (CB-RWA) algorithm locates where cost-efficient upgrades should be implemented. Through numerical examples, we demonstrate that the network capacity improves by 25 per cent by overlaying fibre on 10 per cent of the links, and by 12 per cent by providing hop reduction links comprising 2 per cent of the links. For the upgraded network, we also show the impact of dynamic traffic allocation on the blocking probability. Copyright © 2010 John Wiley & Sons, Ltd.

Cost-reduction using non-uniform traffic in optical networks

Next-generation networks are likely to be non-uniform in all their aspects, including number of lightpaths carried per link, number of wavelengths per link, number of fibres per link, asymmetry of the links, and traffic flows. Routing and wavelength allocation models generally assume that the optical network is uniform and that the number of wavelengths per link is a constant. In practice however, some nodes and links carry heavy traffic and additional wavelengths are needed in those links. We study a wavelength-routed optical network based on the UK JANET topology where traffic demands between nodes are assumed to be non-uniform. We investigate how network capacity can be increased by locating congested links and suggesting cost-effective upgrades. Different traffic demands patterns, hop distances, number of wavelengths per link, and routing algorithms are considered. Numerical results show that a 95% increase in network capacity is possible by overlaying fibre on just 5% of existing links. We conclude that non-uniform traffic allocation can be beneficial to localize traffic in nodes and links deep in the network core and provisioning of additional resources there can efficiently and cost-effectively increase network capacity. © 2013 IEEE.

Message passing for distributed optimisation of power allocation with renewable resources

The increase in renewable energy generators introduced into the electricity grid is putting pressure on its stability and management as predictions of renewable energy sources cannot be accurate or fully controlled. This, with the additional pressure of fluctuations in demand, presents a problem more complex than the current methods of controlling electricity distribution were designed for. A global approximate and distributed optimisation method for power allocation that accommodates uncertainties and volatility is suggested and analysed. It is based on a probabilistic method known as message passing [1], which has deep links to statistical physics methodology. This principled method of optimisation is based on local calculations and inherently accommodates uncertainties; it is of modest computational complexity and provides good approximate solutions.We consider uncertainty and fluctuations drawn from a Gaussian distribution and incorporate them into the message-passing algorithm. We see the effect that increasing uncertainty has on the transmission cost and how the placement of volatile nodes within a grid, such as renewable generators or consumers, effects it.

Efficient asynchronous scheduling algorithms for cost-effective buffered crossbar switches

Buffered crossbar switches have recently attracted considerable attention as the next generation of high speed interconnects. They are a special type of crossbar switches with an exclusive buffer at each crosspoint of the crossbar. They demonstrate unique advantages over traditional unbuffered crossbar switches, such as high throughput, low latency, and asynchronous packet scheduling. However, since crosspoint buffers are expensive on-chip memories, it is desired that each crosspoint has only a small buffer. This dissertation proposes a series of practical algorithms and techniques for efficient packet scheduling for buffered crossbar switches. To reduce the hardware cost of such switches and make them scalable, we considered partially buffered crossbars, whose crosspoint buffers can be of an arbitrarily small size. Firstly, we introduced a hybrid scheme called Packet-mode Asynchronous Scheduling Algorithm (PASA) to schedule best effort traffic. PASA combines the features of both distributed and centralized scheduling algorithms and can directly handle variable length packets without Segmentation And Reassembly (SAR). We showed by theoretical analysis that it achieves 100% throughput for any admissible traffic in a crossbar with a speedup of two. Moreover, outputs in PASA have a large probability to avoid the more time-consuming centralized scheduling process, and thus make fast scheduling decisions. Secondly, we proposed the Fair Asynchronous Segment Scheduling (FASS) algorithm to handle guaranteed performance traffic with explicit flow rates. FASS reduces the crosspoint buffer size by dividing packets into shorter segments before transmission. It also provides tight constant performance guarantees by emulating the ideal Generalized Processor Sharing (GPS) model. Furthermore, FASS requires no speedup for the crossbar, lowering the hardware cost and improving the switch capacity. Thirdly, we presented a bandwidth allocation scheme called Queue Length Proportional (QLP) to apply FASS to best effort traffic. QLP dynamically obtains a feasible bandwidth allocation matrix based on the queue length information, and thus assists the crossbar switch to be more work-conserving. The feasibility and stability of QLP were proved, no matter whether the traffic distribution is uniform or non-uniform. Hence, based on bandwidth allocation of QLP, FASS can also achieve 100% throughput for best effort traffic in a crossbar without speedup.

Experimental determination of effects of water depth on Nymphaea odorata growth, morphology and biomass allocation

Growth, morphology and biomass allocation in response to water depth was studied in white water lily,Nymphaea odorata Aiton. Plants were grown for 13 months in 30, 60 and 90 cm water in outdoor mesocosms in southern Florida. Water lily plant growth was distinctly seasonal with plants at all water levels producing more and larger leaves and more flowers in the warmer months. Plants in 30 cm water produced more but smaller and shorter-lived leaves than plants at 60 cm and 90 cm water levels. Although plants did not differ significantly in total biomass at harvest, plants in deeper water had significantly greater biomass allocated to leaves and roots, while plants in 30 cm water had significantly greater biomass allocated to rhizomes. Although lamina area and petiole length increased significantly with water level, lamina specific weight did not differ among water levels. Petiole specific weight increased significantly with increasing water level, implying a greater cost to tethering the larger laminae in deeper water. Lamina length and width scaled similarly at different water levels and modeled lamina area (LA) accurately (LAmodeled = 0.98LAmeasured + 3.96, R2 = 0.99). Lamina area was highly correlated with lamina weight (LW = 8.43LA − 66.78, R2 = 0.93), so simple linear measurements can predict water lily lamina area and lamina weight. These relationships were used to calculate monthly lamina surface area in the mesocosms. Plants in 30 cm water had lower total photosynthetic surface area than plants in 60 cm and 90 cm water levels throughout, and in the summer plants in 90 cm water showed a great increase in photosynthetic surface area as compared to plants in shallower water. These results support setting Everglades restoration water depth targets for sloughs at depths ≥45 cm and suggest that in the summer optimal growth for white water lilies occurs at depths ≥75 cm.

Monetary cost -efficient query distribution in ISDN -connected heterogeneous databases

Current technology permits connecting local networks via high-bandwidth telephone lines. Central coordinator nodes may use Intelligent Networks to manage data flow over dialed data lines, e.g. ISDN, and to establish connections between LANs. This dissertation focuses on cost minimization and on establishing operational policies for query distribution over heterogeneous, geographically distributed databases. Based on our study of query distribution strategies, public network tariff policies, and database interface standards we propose methods for communication cost estimation, strategies for the reduction of bandwidth allocation, and guidelines for central to node communication protocols. Our conclusion is that dialed data lines offer a cost effective alternative for the implementation of distributed database query systems, and that existing commercial software may be adapted to support query processing in heterogeneous distributed database systems. ^

Interoperable resource brokering with policy-based provisioning and job allocation

The increasing needs for computational power in areas such as weather simulation, genomics or Internet applications have led to sharing of geographically distributed and heterogeneous resources from commercial data centers and scientific institutions. Research in the areas of utility, grid and cloud computing, together with improvements in network and hardware virtualization has resulted in methods to locate and use resources to rapidly provision virtual environments in a flexible manner, while lowering costs for consumers and providers. ^ However, there is still a lack of methodologies to enable efficient and seamless sharing of resources among institutions. In this work, we concentrate in the problem of executing parallel scientific applications across distributed resources belonging to separate organizations. Our approach can be divided in three main points. First, we define and implement an interoperable grid protocol to distribute job workloads among partners with different middleware and execution resources. Second, we research and implement different policies for virtual resource provisioning and job-to-resource allocation, taking advantage of their cooperation to improve execution cost and performance. Third, we explore the consequences of on-demand provisioning and allocation in the problem of site-selection for the execution of parallel workloads, and propose new strategies to reduce job slowdown and overall cost.^

An allocation Malmquist index with an application in the China securities industry

This paper proposes an allocation Malmquist index which is inspired by the work on the non-parametric cost Malmquist index. We first show that how to decompose the cost Malmquist index into the input-oriented Malmquist index and the allocation Malmquist index. An application in corporate management of the China securities industry with the panel data set of 40 securities companies during the period 2005–2011 shows the practicality of the propose model.

Looking for a road to get out for poverty. Is the current allocation of public spending on education in Colombia helping?

This paper presents a methodology to explore the impact on poverty of the public spending on education. The methodology consists of two approaches: Benefit Incidence Analysis (BIA) and behavioral approach. BIA considers the cost and use of the educational service, and the distribution of the benefits among groups of income. Regarding the behavioral approach, we use a Probit model of schooling attendance, in order to determinethe influence of public spending on the probability for thepoor to attend the school. As a complement, a measurement of targeting errors in the allocation of public spending is included in the methodology.

Rate of Belowground Carbon Allocation Differs with Successional Habit of Two Afromontane Trees

Background: Anthropogenic disturbance of old-growth tropical forests increases the abundance of early successional tree species at the cost of late successional ones. Quantifying differences in terms of carbon allocation and the proportion of recently fixed carbon in soil CO2 efflux is crucial for addressing the carbon footprint of creeping degradation. Methodology: We compared the carbon allocation pattern of the late successional gymnosperm Podocarpus falcatus (Thunb.) Mirb. and the early successional (gap filling) angiosperm Croton macrostachyus Hochst. es Del. in an Ethiopian Afromontane forest by whole tree (CO2)-C-13 pulse labeling. Over a one-year period we monitored the temporal resolution of the label in the foliage, the phloem sap, the arbuscular mycorrhiza, and in soil-derived CO2. Further, we quantified the overall losses of assimilated C-13 with soil CO2 efflux. Principal Findings: C-13 in leaves of C. macrostachyus declined more rapidly with a larger size of a fast pool (64% vs. 50% of the assimilated carbon), having a shorter mean residence time (14 h vs. 55 h) as in leaves of P. falcatus. Phloem sap velocity was about 4 times higher for C. macrostachyus. Likewise, the label appeared earlier in the arbuscular mycorrhiza of C. macrostachyus and in the soil CO2 efflux as in case of P. falcatus (24 h vs. 72 h). Within one year soil CO2 efflux amounted to a loss of 32% of assimilated carbon for the gap filling tree and to 15% for the late successional one. Conclusions: Our results showed clear differences in carbon allocation patterns between tree species, although we caution that this experiment was unreplicated. A shift in tree species composition of tropical montane forests (e. g., by degradation) accelerates carbon allocation belowground and increases respiratory carbon losses by the autotrophic community. If ongoing disturbance keeps early successional species in dominance, the larger allocation to fast cycling compartments may deplete soil organic carbon in the long run.

Interoperable Resource Brokering with Policy-based Provisioning and Job Allocation

The increasing needs for computational power in areas such as weather simulation, genomics or Internet applications have led to sharing of geographically distributed and heterogeneous resources from commercial data centers and scientific institutions. Research in the areas of utility, grid and cloud computing, together with improvements in network and hardware virtualization has resulted in methods to locate and use resources to rapidly provision virtual environments in a flexible manner, while lowering costs for consumers and providers. However, there is still a lack of methodologies to enable efficient and seamless sharing of resources among institutions. In this work, we concentrate in the problem of executing parallel scientific applications across distributed resources belonging to separate organizations. Our approach can be divided in three main points. First, we define and implement an interoperable grid protocol to distribute job workloads among partners with different middleware and execution resources. Second, we research and implement different policies for virtual resource provisioning and job-to-resource allocation, taking advantage of their cooperation to improve execution cost and performance. Third, we explore the consequences of on-demand provisioning and allocation in the problem of site-selection for the execution of parallel workloads, and propose new strategies to reduce job slowdown and overall cost.

Análise de custo-efetividade de métodos preventivos para superfície oclusal de acordo com o risco de cárie: resultados de um ensaio clínico controlado

This study presents the results of a cost-effectiveness analysis in a controlled clinical trial on the effectiveness of a modified glass ionomer resin sealant ( Vitremer, 3M ESPE) and the application of fluoride varnish (Duraphat, Colgate) on occlusal surfaces of first permanent molars in children 6-8 years of age (N = 268), according to caries risk (high versus low). Children were examined semiannually by the same calibrated dentist for 24 months after allocation in six groups: high and low risk controls (oral health education every three months); high and low risk with varnish (oral health education every three months + varnish biannually); and high and low risk with sealant (oral health education every three months + a single application of sealant). Economic analysis showed that sealing permanent first molars of high-risk schoolchildren showed a C/E ratio of US$ 119.80 per saved occlusal surface and an incremental C/E ratio of US$ 108.36 per additional saved occlusal surface. The study concluded that sealing permanent first molars of high-risk schoolchildren was the most cost-effective intervention.

Short-term triple therapy with azithromycin for Helicobacter pylori eradication: Low cost, high compliance, but low efficacy

Background: The Brazilian consensus recommends a short-term treatment course with clarithromycin, amoxicillin and proton-pump inhibitor for the eradication of Helicobacter pylori ( H. pylori). This treatment course has good efficacy, but cannot be afforded by a large part of the population. Azithromycin, amoxicillin and omeprazole are subsidized, for several aims, by the Brazilian federal government. Therefore, a short-term treatment course that uses these drugs is a low-cost one, but its efficacy regarding the bacterium eradication is yet to be demonstrated. The study's purpose was to verify the efficacy of H. pylori eradication in infected patients who presented peptic ulcer disease, using the association of azithromycin, amoxicillin and omeprazole. Methods: Sixty patients with peptic ulcer diagnosed by upper digestive endoscopy and H. pylori infection documented by rapid urease test, histological analysis and urea breath test were treated for six days with a combination of azithromycin 500 mg and omeprazole 20 mg, in a single daily dose, associated with amoxicillin 500 mg 3 times a day. The eradication control was carried out 12 weeks after the treatment by means of the same diagnostic tests. The eradication rates were calculated with 95% confidence interval. Results: The eradication rate was 38% per intention to treat and 41% per protocol. Few adverse effects were observed and treatment compliance was high. Conclusion: Despite its low cost and high compliance, the low eradication rate does not allow the recommendation of the triple therapy with azithromycin as an adequate treatment for H. pylori infection.

Cost risk benefit analysis to support chemoprophylaxis policy for travellers to malaria endemic countries

Background: In a number of malaria endemic regions, tourists and travellers face a declining risk of travel associated malaria, in part due to successful malaria control. Many millions of visitors to these regions are recommended, via national and international policy, to use chemoprophylaxis which has a well recognized morbidity profile. To evaluate whether current malaria chemo-prophylactic policy for travellers is cost effective when adjusted for endemic transmission risk and duration of exposure. a framework, based on partial cost-benefit analysis was used Methods: Using a three component model combining a probability component, a cost component and a malaria risk component, the study estimated health costs avoided through use of chemoprophylaxis and costs of disease prevention (including adverse events and pre-travel advice for visits to five popular high and low malaria endemic regions) and malaria transmission risk using imported malaria cases and numbers of travellers to malarious countries. By calculating the minimal threshold malaria risk below which the economic costs of chemoprophylaxis are greater than the avoided health costs we were able to identify the point at which chemoprophylaxis would be economically rational. Results: The threshold incidence at which malaria chemoprophylaxis policy becomes cost effective for UK travellers is an accumulated risk of 1.13% assuming a given set of cost parameters. The period a travellers need to remain exposed to achieve this accumulated risk varied from 30 to more than 365 days, depending on the regions intensity of malaria transmission. Conclusions: The cost-benefit analysis identified that chemoprophylaxis use was not a cost-effective policy for travellers to Thailand or the Amazon region of Brazil, but was cost-effective for travel to West Africa and for those staying longer than 45 days in India and Indonesia.

Cost-effectiveness analysis of PCR for the rapid diagnosis of pulmonary tuberculosis

Background: Tuberculosis is one of the most prominent health problems in the world, causing 1.75 million deaths each year. Rapid clinical diagnosis is important in patients who have comorbidities such as Human Immunodeficiency Virus (HIV) infection. Direct microscopy has low sensitivity and culture takes 3 to 6 weeks [1-3]. Therefore, new tools for TB diagnosis are necessary, especially in health settings with a high prevalence of HIV/TB co-infection. Methods: In a public reference TB/HIV hospital in Brazil, we compared the cost-effectiveness of diagnostic strategies for diagnosis of pulmonary TB: Acid fast bacilli smear microscopy by Ziehl-Neelsen staining (AFB smear) plus culture and AFB smear plus colorimetric test (PCR dot-blot). From May 2003 to May 2004, sputum was collected consecutively from PTB suspects attending the Parthenon Reference Hospital. Sputum samples were examined by AFB smear, culture, and PCR dot-blot. The gold standard was a positive culture combined with the definition of clinical PTB. Cost analysis included health services and patient costs. Results: The AFB smear plus PCR dot-blot require the lowest laboratory investment for equipment (US$ 20,000). The total screening costs are 3.8 times for AFB smear plus culture versus for AFB smear plus PCR dot blot costs (US$ 5,635,760 versus US$ 1,498, 660). Costs per correctly diagnosed case were US$ 50,773 and US$ 13,749 for AFB smear plus culture and AFB smear plus PCR dot-blot, respectively. AFB smear plus PCR dot-blot was more cost-effective than AFB smear plus culture, when the cost of treating all correctly diagnosed cases was considered. The cost of returning patients, which are not treated due to a negative result, to the health service, was higher in AFB smear plus culture than for AFB smear plus PCR dot-blot, US$ 374,778,045 and US$ 110,849,055, respectively. Conclusion: AFB smear associated with PCR dot-blot associated has the potential to be a cost-effective tool in the fight against PTB for patients attended in the TB/HIV reference hospital.