Efficiently Computing Real Roots of Sparse Polynomials

We propose an efficient algorithm to compute the real roots of a sparse polynomial $f\in\mathbb{R}[x]$ having $k$ non-zero real-valued coefficients. It is assumed that arbitrarily good approximations of the non-zero coefficients are given by means of a coefficient oracle. For a given positive integer $L$, our algorithm returns disjoint disks $\Delta_{1},\ldots,\Delta_{s}\subset\mathbb{C}$, with $s<2k$, centered at the real axis and of radius less than $2^{-L}$ together with positive integers $\mu_{1},\ldots,\mu_{s}$ such that each disk $\Delta_{i}$ contains exactly $\mu_{i}$ roots of $f$ counted with multiplicity. In addition, it is ensured that each real root of $f$ is contained in one of the disks. If $f$ has only simple real roots, our algorithm can also be used to isolate all real roots. The bit complexity of our algorithm is polynomial in $k$ and $\log n$, and near-linear in $L$ and $\tau$, where $2^{-\tau}$ and $2^{\tau}$ constitute lower and upper bounds on the absolute values of the non-zero coefficients of $f$, and $n$ is the degree of $f$. For root isolation, the bit complexity is polynomial in $k$ and $\log n$, and near-linear in $\tau$ and $\log\sigma^{-1}$, where $\sigma$ denotes the separation of the real roots

Energy Model of Networks-on-Chip and a Bus

A Network-on-Chip (NoC) is an energy-efficient onchip communication architecture for Multi-Processor Systemon-Chip (MPSoC) architectures. In earlier papers we proposed two Network-on-Chip architectures based on packet-switching and circuit-switching. In this paper we derive an energy model for both NoC architectures to predict their energy consumption per transported bit. Both architectures are also compared with a traditional bus architecture. The energy model is primarily needed to find a near optimal run-time mapping (from an energy point of view) of inter-process communication to NoC link

Modeling the Structure and Complexity of Engineering Routine Design Problems

This paper proposes a model to structure routine design problems as well as a model of its design complexity. The idea is that having a proper model of the structure of such problems enables understanding its complexity, and likewise, a proper understanding of its complexity enables the development of systematic approaches to solve them. The end goal is to develop computer systems capable of taking over routine design tasks based on generic and systematic solving approaches. It is proposed to structure routine design in three main states: problem class, problem instance, and problem solution. Design complexity is related to the degree of uncertainty in knowing how to move a design problem from one state to another. Axiomatic Design Theory is used as reference for understanding complexity in routine design

Energy-Efficient NoC for Best-Effort Communication

A Network-on-Chip (NoC) is an energy-efficient on-chip communication architecture forMulti-Processor System-on-Chip (MPSoC) architectures. In an earlier paper we proposed a energy-efficient reconfigurable circuit-switched NoC to reduce the energy consumption compared to a packetswitched NoC. In this paper we investigate a chordal slotted ring and a bus architecture that can be used to handle the best-effort traffic in the system and configure the circuitswitched network. Both architectures are compared on their latency behavior and power consumption. At the same clock frequency, the chordal ring has the major benefit of a lower latency and higher throughput. But the bus has a lower overall power consumption at the same frequency. However, if we tune the frequency of the network to meet the throughput requirements of control network, we see that the ring consumes less energy per transported bit

Intergenerational redistribution of income through capital funding pension schemes: simulating the Dutch pension fund ABP

In most countries, the largest proportion of the pension benefits that are paid out to the elderly are brought together by the contributions of the active population. This type of financing is known as a Pay-As-You-Go-scheme. In this scheme, an important ‘chain of solidarity' covers for the pension of the preceding generation. So, there is a pattern of winners and losers that is caused by the rates of ageing of the populations, in combination with PAYG-pension schemes. In pension schemes based on the Capital Funding (CF) type, individuals of every generation build up a certain future pension claim. So, every generation builds up its own future pension benefit in this type of scheme. Hence, CF pension schemes are believed not to rely on income flows between generations, since every generation finances its own future pension. The advantage then is that there are no winners or losers, from the generational point of view at least, so that demographic developments cannot jeopardize the system. But, this only holds for Defined-Contribution (DC) pension systems. In practice, we also observe Defined-Benefit (DB) pension systems. In fact, the larger part of the occupational pensions schemes in the Netherlands are DB ones. For this type of schemes it holds that absence of intergenerational income flows is a too optimistic view, though the redistribution is not that strongly as in the case of PAYG schemes. The central question in this contribution is whether intergenerational redistribution of income occurs via Capital Funding in case of DB pension schemes in the Netherlands. To that end we analyse the Dutch civil servants' pension fund in the Dutch dynamic microsimulation model NEDYMAS.microsimulation; ageing; social hypotheses; poverty; inequality

An Information Model for Product Development: A Case Study at PHILIPS Shavers

This paper presents an investigation into the development of an information model to support the Product Development Process (PDP) of shaving devices at PHILIPS. Firstly, challenges of the PDP were identified by carrying out interviews with several systems engineers and product architects. It was found that an increase in product functions combined with a shorter time to market has resulted in higher information densities and larger information flows during the PDP. As a result, managing uncertainty, communication and documentation has become increasingly difficult. Secondly, the information flow in the organization was formalized at the hand of interviews with the development staff in all involved departments and by investigating the available documentation of former projects. Thirdly, the information flow was translated into an information model to support the future development of new shaving devices. The resulting model consists of two paper based design support tools, namely, the MetroChart and the Design Parameter Matrices. The former is a paper-based design support tool that provides a compact overview of the processes that different development teams have to undergo during the PDP of a new shaver. The latter provides a detailed description of the relations between design parameters, process steps, and components. Current efforts are made to determine how to implement the model from an organizational point of view, as the number of developers, disciplines and departments involved in the design of this product is rather large and small errors can lead to large losse

The effect of ethnicity on appendicular bone mass in white, coloured and Indian schoolchildren

Ethnic differences in the incidence and prevalence of osteoporosis have been shown throughout the world. In South Africa the prevalence of osteoporosis is much higher in whites than in blacks. This is surprising, since factors that might predispose to reduce bone mass are more preponderant in black communities. The present research was undertaken to detertnine whether differences in bone mass during the period of bone accretion could explain the difference in the incidence of osteoporosis. In this paper we report on differences in appendicular bone Inass between white, coloured and Indian children and teenagers (6 - 18 years) from Johannesburg. The effects of weight, height, puberty and skinfold thickness on bone mass were also assessed. The bone width (BW) of white boys was greater than that of Indian boys, while the bone mineral content (BMC) and BMC/BW were greater in white boys than in both Indian and coloured boys. After adjustment for differences in weight and height, the BW of coloured boys was significantly greater than that of white boys, while all differences in BMC and BMC/BW becaIne non-significant. For girls there were no significant differences in bone mass measurements, but after adjustment for height and weight coloured girls had significantly greater BMC and BMC/BW than either white or Indian girls. This greater weight- and height-adjusted bone mass in coloured girls is consistent with the impression of a lower incidence of osteoporosis in coloured women than in white women

Brane Dynamics From the Born-Infeld Action

We use the abelian Born-Infeld action for the worldvolume gauge field and transverse displacement scalars to explore new aspects of D-brane structure and dynamics. We study several classic gauge field configurations, including point charges in any worldvolume dimension and vortices in two worldvolume dimensions, and show that, with an appropriate excitation of the transverse coordinate field, they are BPS-saturated solutions. The Coulomb point charge solutions turn out to represent, with considerable fidelity, fundamental strings attached to the brane (their magnetic counterparts describe D1-branes attached to D3-branes). We also show that S-matrix for small excitations propagating on the point charge solution is consistent with (and gives further illuminating information about) Polchinski's effective open string boundary condition.Comment: 16 pages, 3 figures. Minor typos fixe

Regular consumption of black tea increases circulating kynurenine concentrations: A randomized controlled trial

AbstractBackgroundCirculating neopterin and the ratio of kynurenine to tryptophan (KYN/TRP) concentrations are biomarkers of immune activation that have been linked to cardiovascular and total mortality. Several in vitro studies indicated that tea flavonoids and other antioxidants can modulate tryptophan breakdown rates and neopterin production in immune cells. We aimed to assess the effects of regular black tea consumption on tryptophan and neopterin metabolisms in vivo.MethodsParticipants were healthy individuals, with no major illnesses and having normal to mildly elevated systolic blood pressure. They were randomly assigned to consume 3cups/day of either powdered black tea solids (tea; n=45) or a flavonoid-free caffeine-matched beverage (control; n=49). Serum concentrations of tryptophan, kynurenine and neopterin were assessed at baseline and again at 3 and 6months after daily ingestion of the respective beverage.ResultsRegular consumption of tea over 6months, compared to control, did not significantly alter neopterin (p=0.13) or tryptophan (p=0.85) concentrations, but did result in significantly higher kynurenine (p=0.016) and KYN/TRP (p=0.012). Relative to the control group, in the tea group kynurenine and KYN/TRP increased during the treatment period by 0.28μmol/L (95% CI: −0.04, 0.60) and 3.2μmol/mmol (95% CI: −1.6, 8.0), respectively at 3months, and by 0.48μmol/L (95% CI: 0.16, 0.80) and 7.5μmol/mmol (95% CI: 2.5, 12.5), respectively at 6months.ConclusionsIncreased circulation of kynurenine and KYN/TRP following regular black tea consumption may indicate enhanced tryptophan breakdown, possibly due to immune activation-induced tryptophan degrading enzyme indoleamine 2,3-dioxygenase.General significanceThe influence of black tea consumption on biomarkers of immune system activation could relate to its general health benefits. Data suggests that the net effect strongly depends on the individual immune state, being stimulatory in healthy individuals, while acting more immune dampening in situations with an inflammatory background

Work in progress: developing tools that support the design of easily maintainable rolling stock

Maintenance activities strongly influence the operational availability and life cycle costs of rolling stock. To achieve an effective and efficient maintenance process, it is essential that the design of the trains and its maintenance service are well-aligned. We conduct research on how the design of industrial equipment, such as rolling stock, and the design of its maintenance service influence the maintenance process. We use our findings for the development of methods and tools that support the use of maintenance knowledge in the equipment design process. An example of a past train development project shows that re- designing the mounting construction of a compressor has led to lower maintenance costs and a higher availability of both the trains and the maintenance resources. Based on such examples from industry and from findings in the literature, we expect that our research can contribute to better design decisions, which ultimately results in production systems that are cost-effective over their whole life tim