bluuebunny/crossref_metadata_2025 huggingface dataset:
Informal care and economic appraisal: A discussion of possible methodological approaches
Authors: Smith Kirsteen , Wright Ken
Published: May 2007

The role played by informal carers in the care of people with chronic disabilities is well known. Given its importance, it is essential to consider the evaluation methodology applied in economic appraisals of different care options. Few studies attempt any evaluation and those that do use varied, inconsistent and controversial methodologies. This paper aims to elicit the major issues and methodological problems related to economic appraisal of informal care.

The main concern over the present methods utilized is the lack of explicit exploration of the benefits, as perceived by carers. Carers, through their decision to care it is argued, will consider both costs and benefits. Although concepts encompassed by benefits tend to be less tangible they may considerably outweigh any financial burdens.

Various methods have been utilized in the past. Financial outlays are fairly straightforwardly costed, personal effort on the part of carers causes more problems. Methods applied include: the cost of substitute services; state benefits; and travel time values. The most useful is probably the latter, although it is not problem‐free.

Assessing benefits relating to concepts of direct and indirect utility and welfare is more complex and difficult to measure. Despite considerable literature on carers' attitudes, often these concepts are not applied (especially to residential care options) or if they are, negative aspects are emphasized (with domiciliary care).

A useful application of economic appraisal would elicit optimal solutions to care dilemmas. Producing economic burden information about informal care may not be particularly constructive.

Brief assessment of eight scenarios of care, considering cost differences for the public sector and the preferences of patient and carer gives insight to the problem. It emphasizes the complexity of the issue and the essential role likely to be placed on care managers in helping carers to maximize the net benefit of their efforts.
Private versus social opportunity cost of time: Valuing time in the demand for health care
Authors: Torgerson D. J. , Donaldson C. , Reid D. M.
Published: May 2007

In this paper we examine whether the current method of valuing time within economic appraisals is appropriate. The cost to society of time taken to use health care may differ from the private opportunity cost of such time. However, demand for health care may be affected by the private opportunity time cost and not by the value of time to society. In this paper we show that the private opportunity cost of time is a better predictor of demand for a screening service than the societal approach. It is important, therefore, to use the private opportunity cost of time when assessing the demand for, and impact of, a health care intervention.
Valuing future benefits
Authors: Cairns John A.
Published: May 2007

This paper reports the results of a study of time preference amongst the general public in the Grampian region of Scotland. The subjects, who were selected randomly from the electoral roll, were offered a series of inter‐temporal choices. Their responses were used to calculate private financial time preference rates, social non‐monetary time preference rates and social financial time preference rates. The paper investigates the relationship between these three measures of time preference in both the short and the long run. It also explores the effects of individual characteristics, including age, and health, on the implicit discount rates.
Is it possible to reduce tobacco consumption via alcohol taxation?
Authors: Jimenez Sergio , Labeaga José M.
Published: May 2007

Recent studies with Spanish data suggest that indirect taxation is a potential instrument to reduce tobacco consumption but the magnitude of the estimated price elasticity limits the effectiveness of the taxes. However, if the separability restriction does not hold between tobacco and other goods, the results obtained could be misleading. This shortcoming of previous analyses leads us to formulate a demand system with alcohol, tobacco and other goods so as to estimate and test complementary effects and to assess the possibility for reducing consumption by indirect taxation of complementary commodities. We use the Spanish Family Expenditure Survey to carry out a cross‐section study which allows us to estimate demand models under different assumptions about the nature of zero expenditures and to test the effectiveness of indirect taxation. The findings tend to support our initial suspicions about the inadequacy of imposing separability and point out the importance of alcohol taxation to reduce tobacco consumption. However, given the structure of the data used, these results should be viewed with caution and must be confirmed by additional evidence.
Shared ‘features’ in prices: Income and price elasticities for health care expenditures
Authors: Saez Marc , Murillo Carles
Published: May 2007

The evidence found in most studies suggests a strong positive relationship between health care expenditure and gross domestic product. However, this evidence weakens with respect to the actual value of the income elasticity. There are two possible sources of these discrepancies, the use of arbitrary deflators and specification errors. We find that health PPP cannot be taken as a ‘universal’ price index. The problem is that its components do not move together. Nevertheless, we derive a ‘universal’ health price index from a dynamic system in which its components share both short and long run co‐movements. The omission of relevant explanatory variables seems to be the main cause of the discrepancies. We confirm that there exists a strong positive relationship between per capita health care expenditure and per capita GDP. However we estimate a long run income elasticity at or around unity, although it is greater than unity for the countries with lower per capita income (Spain and Ireland). The results for income elasticity are the same regardless of whether health care expenditure is converted using the GDP PPP or the ‘universal’ health price index. The importance of non‐income variables is also confirmed, in particular the relative price of health care. We find that relative price has a strong rationing effect on the quantity of health demanded and has no effect on the expenditures.
Some moral problems in medicine
Authors: Warnock Baroness
Published: May 2007

An earlier version of the following paper was presented at the Bicentennial Conference of the Plymouth Medical Society, April 15th, 1994.

Mary Warnock is a member of the House of Lords and a distinguished philosopher who, until her retirement, was Mistress of Girton College Cambridge. She chaired the Committee of Inquiry into Human Fertilization and Embryology from 1982 to 1984, as a result of which The Warnock Report, entitled ‘A Question of Life’, was published in 1985.
An internal rate of return approach to investigate pharmacist supply in the united states
Authors: Mott David A. , Kreling David H.
Published: May 2007

Internal rates of return were used to examine the status of pharmacist supply in the United States between the years 1987‐1991. Age‐earnings profiles were estimated for pharmacists, college graduates and high school graduates. Rates of return to pharmacists and college graduates were compared and a ratio of the pharmacist rate to the college graduate rate was computed for each year. Results suggest a shortage of pharmacists in the United States. Enrollments in pharmacy schools and adopted changes in the training of pharmacists are discussed in relation to their effects on the pharmacist labour market.
Should you eat breakfast? Estimates from health production functions
Authors: Kenkel Donald S.
Published: May 2007

This paper uses an econometric specification based on the health production function approach to examine the importance of lifestyles for adult health. The approach treats health practices such as eating breakfast, smoking, and exercise as inputs into the production of good health; several output measures are explored. The econometric models estimated with data from the 1985 Health Interview Survey show broad agreement with conventional wisdom about the importance of healthy lifestyles. This paper also investigates the role schooling plays in the production of good health. Schooling is found to be related to good health even after controlling for differences in observable health inputs. However, lack of support for a plausible specification of the productive efficiency hypothesis casts some doubt on the interpretation that schooling increases the efficiency of the household production of health.
An economic model of the market for hospital treatment for non‐urgent conditions
Authors: Goddard J. A. , Malek M. , Tavakoli M.
Published: May 2007

This paper develops an economic model of the market for treatment of waiting list conditions, in which complainants choose between private treatment, NHS treatment and no hospital treatment. This choice depends on a number of clinical and non‐clinical factors, which enter the demand functions for private and NHS treatment. Among the key influences are the price of private treatment and the expected duration of wait for NHS treatment, both of which are endogenous variables in the model. Given a pair of private sector and NHS supply functions, expressions are obtained for the price and expected wait at which demand and supply are simultaneously equated in both the private sector and the NHS. The paper concludes by exploring the responsiveness of the equilibrium to various demand side and supply side shocks.
Solo versus group practice in the medical profession: The influence of malpractice risk
Authors: Bradford W. David
Published: May 2007

While Partnerships are a significant form of business organization in many sectors of the economy, relatively little is known about the incentives which lead to their formation. This paper explores the formation of partnerships among office based physicians when facing some risk of malpractice litigation. Theoretical results indicate that malpractice exposure can increase the incentives to shirk within a partnership, and so exert a significant influence on the decision to form a partnership. Empirical results find that malpractice risk has the expected negative effect on some partnership formation.
The political economy of health system reform in Israel
Authors: Chernichovsky Dov , Chinitz David
Published: May 2007

On June 15, 1994, the Israeli Parliament voted to enact the National Health Insurance bill (NHI). The bill marks the end of a process that lasted for virtually as long as Israel's almost 50 year history. Israel's attempts at health reform began long before the current spate of reforms in many Western countries. Faced with many of the same problems of access, equity and cost control common to many of its counterparts, Israel initiated a reform process based on the recommendations of a prominent State Commission of Inquiry into the Israeli Health System (the Netanyahu Commission) which reported to the Government in 1990.2 The Commission's proposals were based on a diagnosis indicating that the major problems of the system stem from the lack of clarity regarding the rights of citizens to health care, the lack of a clear allocation of responsibility and accountability among government, insurance or sick funds, and providers in the system, and undue centralization of system operations. This diagnosis led to three major planks for reform: (1) enactment of national health insurance legislation granting a basic package of care to each citizen and hence bringing most of the system's finance under public auspices; (2) divesting the Government from the organization, management and provision of care; hence integrating the management of preventive and psychiatric services provided by the government with the primary and other services provided by sick funds, and granting financial and operational independence to at least government hospitals; and (3) restructuring the Ministry of Health.

As is often the case in public policy, more consensus surrounds the diagnosis than the solutions. As a result, nearly four years of implementation efforts have only recently resulted in a major breakthrough. In this paper we make an effort to outline the inherent weaknesses of the Israeli health care system that have led to the crisis in the mid 1980s, summarize the recommendations of the State Commission for structural change in the system, and review the politics of implementing the recommended reforms.
Health, health care, and the environment. Econometric evidence from German micro data
Authors: Erbsland Manfred , Ried Walter , Ulrich Volker
Published: May 2007

The paper develops and applies a Grossman‐style health production model set up in discrete time to explain the impact of environmental pollution on the demand for both health and health care. In order to introduce the environment, our analysis takes changes in environmental conditions to influence the rate at which an individual's stock of health depreciates. While the theoretical part of our paper also contains a discussion of the full model, we restrict our empirical analysis to a submodel which is known as the pure investment model. This is because the other submodel, the pure consumption model, implies a rather implausible case of satiation with respect to the individual's preferences.

Our empirical findings are based on data taken from the German Socio‐economic Panel. The stock of health capital and environmental pollution are treated as latent variables and estimated using a Linear Covariance Structures model. The quality of the environment turns out to be an important determinant of health capital. From the point of view of health economics, improvements in environmental conditions can be interpreted as preventive measures. In terms of prevention, public policies designed to protect the environment also yield significant health effects. As regards health care demand the influence is not clearcut, i.e., one cannot necessarily expect a reduction in resource use.
Workstation redesign for a repetitive drill press operation: A combined work design and ergonomics approach
Authors: Das Biman , Shikdar Ashraf A. , Winters Troy
Published: May 2007

A typical or conventional workstation for a repetitive drill press operation was evaluated and subsequently redesigned by incorporating the concepts and principles of work design and ergonomics. The production task comprised of drilling four holes on a prepared steel plate. A methods–time measurement (MTM) analysis was conducted to eliminate unnecessary motions and improve the necessary (work) motions involved in task performance. The specific features of the redesigned workstation were specially designed equipment (jig, fixture, etc.), a suitable adjustable chair, proper work height, a placement of tools/equipment within reach envelope, and a comprehensive operator training method. An experimental investigation was conducted to evaluate and test the redesigned workstation in terms of operator productivity (production quantity and quality output) and satisfaction. The increases in quantity (number of holes drilled) and quality (number of good holes drilled) output were 22 and 50%, respectively, for the redesigned workstation compared to the typical or conventional workstation. The high improvement in quality output (50%) could be attributed to the improved design of the jig and fixture and the comprehensive operator training method, which emphasizes the quality aspect of production output. The improvement in operator satisfaction (scores) were highly significant. This investigation has demonstrated the beneficial effect of a combined work design and ergonomics approach, especially for the redesign of a workstation for a repetitive drill press operation. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 395–410, 2007.
A case study of serial‐flow car disassembly: Ergonomics, productivity and potential system performance
Authors: Kazmierczak Karolina , Neumann W. Patrick , Winkel Jørgen
Published: May 2007

A recent European Union (EU) directive increases demands on car recycling. Thus, present craft‐type disassembly systems need reconfiguration in order to be more efficient. A line‐based system tested in the Netherlands was investigated regarding system performance and ergonomics. The system had reduced performance compared to the design specifications due to such factors as system losses, operator inexperience, and teamwork deficiencies. Operators' peak low back loads were lower than in Swedish craft‐type systems. Direct, value‐adding work comprised 30% of the workday, compared to about 70% in the Swedish manufacturing industry. Alternative system configurations were simulated and discussed using a novel combination of flow and human simulations. For example, a smaller variation in cycle time implied higher output in number of cars per week and larger operator cumulative loading on the low back. In all models the cumulative load was high compared to the loads previously recorded in assembly work. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 331–351, 2007.
Substrate adhesion affects contraction and mechanical properties of fibroblast populated collagen lattices
Authors: Chen Meng‐Yi , Sun Yu‐Long , Zhao Chunfeng , Zobitz Mark E. , An Kai‐Nan , Moran Steven L. , Amadio Peter C.
Published: May 2007

Fibroblasts can condense a hydrated collagen lattice to a tissue‐like structure. The purpose of this study was to evaluate the effect of substrate adhesion on the contraction and mechanical properties of fibroblast populated collagen lattices. Bacteriological grade polystyrene (BGPS) plates and tissue culture polystyrene (TCPS) plates were used as substrates for incubation of fibroblast populated collagen lattices. Hydrophobicity of the polystyrene surfaces was measured by the static sessile contact angle method. Collagen lattice contraction was recorded for 2 weeks, after which the lattices were mechanically tested. The BGPS culture plate had a significantly larger contact angle and was more hydrophobic than the TCPS culture plate. Both hydrophobicity and peripheral detachment of the collagen gel significantly decreased the time lag before initiation of gel contraction and increased the strength of the fibroblast populated collagen lattices. Substrate adhesion affects the contractility and strength of cell seeded collagen gels. This information may be useful in developing tissue engineered tendons and ligaments. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Hyperthermia inhibits cell proliferation and induces apoptosis: Relative signaling status of P53, S100A4, and Notch in heat sensitive and resistant cell lines
Authors: Basile Antonio , Biziato Daniela , Sherbet Gajanan V. , Comi Paola , Cajone Francesco
Published: May 2007

The effects of hyperthermia on the expression of p53, the apoptosis‐associated genes Bax and Bcl‐2, Notch and S100A4 have been studied in the HepG2 cell line and the HUT cell line derived from HepG2, adapted for growth in hyperthermic conditions. Hyperthermia inhibits cell proliferation and induces apoptosis. HepG2 and HUT cells differed in respect of anchorage to growth surface, degree of proliferation and apoptosis and expression of p53, Bax, Bcl‐2, Notch, and S100A4 genes. The induction of apoptosis and the inhibition of cell proliferation occurred independently of p53, and independently also of involvement of the apoptosis family genes Bax and Bcl‐2. We demonstrate novel and marked differences between transient heat shock and heat adaptation in respect of pathways of signaling and generation of phenotypic effects in vitro. Different signaling patterns have been identified here. Pathways of signaling by S100A4, by its interaction with and sequestration of p53, and by Notch also seem differentially operational in the induction of apoptosis, and both appear to be activated as alternative pathways in the context of hyperthermia signaling independently of p53. J. Cell. Biochem. 103: 212–220, 2008. © 2007 Wiley‐Liss, Inc.
Continuous culture of two lancelets and production of the second filial generations in the laboratory
Authors: Zhang Qiu‐Jin , Sun Yi , Zhong Jing , Li Guang , Lü Xiao‐Mei , Wang Yi‐Quan
Published: May 2007

The lancelet is considered to be a promising laboratory model animal. To establish laboratory colonies of lancelet, we collected parental lancelets of Branchiostoma belcheri and B. japonicum (previously named as B. belcheri tsingtauense) with fully developed gonads from Xiamen Rare Marine Creature Conservation Areas (Fujian, China) on dates just before their spawning in the field in 2005. Those parental lancelets spawned spontaneously in the laboratory and produced thousands upon thousands of fertilized eggs. After carefully hatching and maintaining for almost 1 year, we successfully obtained about 500 first generation (F1) adults of B. belcheri and 3,300 of B. japonicum. Part of those F1 lancelets ripened and spontaneously spawned in 2006, and several thousands of second generation (F2) individuals of both species were produced. The young F2 lancelets are growing in good condition and some of B. japonicum initiated gonad development in December, 2006. Our experience emphasizes that cleanness of settlement substratum and sufficient food supply are important factors for long‐term culture of lancelets in the laboratory. J. Exp. Zool. (Mol. Dev. Evol.) 308B:464–472, 2007. © 2007 Wiley‐Liss, Inc.
Glial cell line‐derived neurotrophic factor protects astrocytes from staurosporine‐ and ischemia‐ induced apoptosis
Authors: Yu Albert Cheung Hoi , Liu Rong Yu , Zhang Yun , Sun Hao Rui , Qin Lu Ye , Lau Lok Ting , Wu Bing Yi , Hui Hung Kit , Heung Man Yeung , Han Ji Sheng
Published: May 2007

Glial cell line‐derived neurotrophic factor (GDNF) promotes the survival and functions of neurons. It has been shown to be a promising candidate in the treatment of ischemia and other neurodegenerative diseases. We transfected mouse astrocytes in primary cultures with a human GDNF gene and found that their conditioned medium could not only support the growth and survival of cultured dopaminergic neurons but also protect astrocytes from staurosporine‐ and ischemia‐induced apoptosis. This indicated that these transfected astrocytes could release GDNF. A similar protective effect on astrocytes against apoptosis was evident when recombinant human GDNF was used. Moreover, GDNF reduced caspase‐3 activity but not that of caspase‐1 in cultured astrocytes after ischemia treatment. Thus, GDNF protects astrocytes from apoptosis by inhibiting the activation of caspase‐3. © 2007 Wiley‐Liss, Inc.
The use of conformation‐specific ligands and assays to dissect the molecular mechanisms of neurodegenerative diseases
Authors: Leliveld S. Rutger , Korth Carsten
Published: May 2007

The use of conformation‐specific ligands has been closely linked to progress in the molecular characterization of neurodegenerative diseases. Deposition of misfolded or misprocessed proteins is now recognized as a hallmark of all neurodegenerative diseases. Initially, dyes like Congo red and thioflavin T were used as crudely conformation‐specific ligands for staining the β‐sheeted protein components of amyloid deposits in neurodegenerative diseases such as Alzheimer disease (AD) and prion disease, the two diseases in which protein conformations were distinguished early on. This conformational characterization of extracellular protein deposits with dyes ultimately led to the identification of key players in the disease processes. The recent discovery of intermediate conformational species, i.e., soluble oligomers for AD and PK‐sensitive PrPSc for prion disease, whose conformation and assembly are thought to be distinct from both the physiological and the fibrillar conformational states, replaced the former notion that the microscopic protein deposits themselves caused disease. This insight and the generation of conformation‐specific monoclonal antibodies to these conformers further advanced diagnosis and the understanding of molecular mechanisms of AD and are likely to do so in other neurodegenerative diseases. Here we review how conformer distinction performed by a variety of different techniques, including biophysical, biochemical, and antibody‐based methods, led to the current molecular concepts of AD and the prion diseases. We provide an outlook on the application of these techniques in advancing the understanding of molecular mechanisms of other neurodegenerative diseases or degenerative brain conditions. © 2007 Wiley‐Liss, Inc.
Evidences of the cardioprotective potential of fruits: The case of cranberries
Authors: Ruel Guillaume , Couillard Charles
Published: May 2007

Eating a healthy balanced diet, is one of the most important and relevant ways to delay and prevent various health complications including cardiovascular disease (CVD). Among the nutritional factors that have been investigated in recent years, dietary fat intake may be the one that has been most targeted. However, there is also clear epidemiological evidence that increased fruits and vegetables intake can significantly reduce the risk of CVD, an effect that has been suggested to be resulting to a significant extent, from the high polyphenol content of these foods. Numerous polyphenolic compounds such as flavonoids have been identified as having strong antioxidant properties. Most interesting is the fact that, in addition to being one of the largest groups of antioxidant phytochemicals, flavonoids are also an integral part of the human diet as they are found in most fruits and vegetables. Cranberries are one of the most important sources of flavonoids that have a strong antioxidant and anti‐inflammatory capacities. Thus, consumption of cranberries or their related products could be of importance not only in the maintenance of health but also in preventing CVD. The following review will present evidences supported for the most part by clinical observations that cranberries can exert potentially healthy effects for your heart.
Antioxidant activity and antimicrobial effect of berry phenolics – a Finnish perspective
Authors: Heinonen Marina
Published: May 2007

In Finland, berries are part of the traditional diet significantly contributing to the intake of flavonoids and other phenolic compounds. Compositional data on phenolic compounds in berries has been rapidly accumulating and included in the national food composition database. Among the different bioactive substances in berries, phenolic compounds including flavonoids, tannins, and phenolic acids have received considerable interest due to their effects in food and health. A great amount of in vitro evidence exists showing that berry phenolics are powerful antioxidants. However, the antioxidant effect of berry phenolics is strongly dependent on the choice of berry raw material, as the antioxidant activity differs between the different phenolic constituents, including anthocyanins, ellagitannins, and proanthocyanidins. In foods, the antioxidant effect is also influenced by the structure of food. Tannin‐containing berries exhibit antimicrobial properties against pathogenic bacteria, thus offering many new applications for food industry. Much of the interest in berry phenolics has focused on cranberries and both cultivated and wild blueberries, although also other berries including black currants, cloudberries, lingonberries, and red raspberries posses promising bioactivities that may have relevance to human health. Antioxidant activity of berry phenolics, in addition to other mechanisms, may contribute to human health, but the possible relationship remains yet to be scientifically substantiated.
Why a second house?
Authors: D'Alemberte Talbot , Fishburne Charles C.
Published: May 2007

Unicameral system seen as providing adequate checks as well as increased simplicity and responsibility.
Miracle on main street
Authors: Crossley Robert Pierce
Published: May 2007

Grand Junction citizens create own plan to revive a decaying downtown area as a thing of beauty, utility.
Reform is possible
Authors: Tydings Joseph D.
Published: May 2007

Sound constitutions, reorganization, re‐thinking seen as needed to halt withering of the states.
Following through
Authors: Stuart Julia Davis
Published: May 2007

Blueprints are dandy but it will take hard work to achieve needed reforms in states.
Proceed with a plan
Authors: Netzer Dick
Published: May 2007

Scramble for vast federal assistance calls for long‐range approach to solve fiscal imbalance.
Governor—Salesman
Authors: Wyner Alan J.
Published: May 2007

Restrictions on executive have caused many to focus on industrial promotion and good publicity.
Paying for transit
Authors: Hall Richard A.
Published: May 2007

States must enact legislation, provide financial assistance for urban systems to be successful.
Every drop counts
Authors: Stevens Leonard A.
Published: May 2007

Scientific research, natural cleansing processes help town to reclaim waste water for recreation.
A great partnership
Authors: Wheeler John P.
Published: May 2007

States must revamp policies, fashion creative roles to achieve ‘senior’ status in a vital federal system.
Who is legislating?
Authors: Bryan Frank M.
Published: May 2007

No drastic changes in ‘kinds’ of representatives are seen as result of Vermont's reapportionment.
Multi‐commodities transportation schedules over time
Authors: Tapiero C. S. , Soliman M. A.
Published: May 2007

Multi‐commodity transportation problems over time are formulated by a system of differential equations and optimal transport flows determined by the application of a maximum principle with time delays. Applications to logistics and distribution management problems are then considered and resolved.
The shortest and the K‐shortest routes as assignment problems
Authors: Weintraub A.
Published: May 2007

The problem of finding a shortest route in a network with unrestricted costs is approached through solving an assignment problem associated to the network.

The upper bound on the number of elementary calculations required for the solution is 0(m3). However, in most cases, the actual number of computations is considerably less and depends on different network characteristics than Dynamic Programming algorithms do. In examples of networks generated stochastically, this number was below 0(m2.5).

A parametric analysis is presented. It is shown that if after a shortest route is determined, the costs on all arcs incident into or out of a node are modified in any form, at most 0(m2) elementary calculations will determine a new optimal solution. This feature, shared by Dynamic Programming algorithms only for cases where all cost decrease, can be applied to problems such as the determination of the K‐shortest routes and the K‐smallest assignments, leading to upper bounds of 0(Km3) in both cases.
The flow deviation method: An approach to store‐and‐forward communication network design
Authors: Fratta L. , Gerla M. , Kleinrock L.
Published: May 2007

Two problems relevant to the design of a store‐and‐forward communication network (the message routing problem and the channel capacity assignment problem) are formulated and are recognized to be essentially non‐linear, unconstrained multicommodity (m.c.) flow problems. A “Flow Deviation” (FD) method for the solution of these non‐linear, unconstrained m.c. flow problems is described which is quite similar to the gradient method for functions of continuous variables; here the concept of gradient is replaced by the concept of “shortest route” flow. As in the gradient method, the application of successive flow deviations leads to local minima. Finally, two interesting applications of the FD method to the design of the ARPA Computer Network are discussed.
Cutsets and partitions of hypergraphs
Authors: Lawler E. L.
Published: May 2007

A hypergraph is a combinatorial structure with nodes and arcs, similar to an ordinary „linear”︁ graph, except that arcs are incident to arbitrary subsets of nodes, instead of pairs of nodes. Cutsets of hypergraphs are defined in a natural way, and it is shown that optimal cutsets can be found by means of a network flow computation. The optimal cutset computation can be used to generate a family of subsets of nodes, which we call LS sets. Intuitively, an LS set is a subset of nodes that are more strongly connected to each other than to nodes in the complementary set. LS sets are useful for constructing optimal or near‐optimal partitions of the nodes. A polynomial‐bounded partitioning algorithm is presented, and various applications are suggested.
A sufficient condition for a matrix to be totally unimodular
Authors: Commoner F. G.
Published: May 2007

Two conditions for a matrix to be totally unimodular are obtained; one sufficient, one necessary and sufficient. Both conditions involve a directed bipartite graph obtained from a {1, −1, 0}‐valued matrix, and both are generalizations of the fact that directed graphs and 2‐colorable undirected graphs have totally unimodular incidence matrices.
Implementation and computational comparisons of primal, dual and primal‐dual computer codes for minimum cost network flow problems
Authors: Glover F. , Karney D. , Klingman D.
Published: May 2007

This paper presents extensive computational experience with a special purpose primal simplex algorithm. The performance is compared to that of several “state of the art” out‐of‐kilter computer codes. The computational characteristics of several different primal feasible start procedures and pivot selection strategies are also examined.

The study discloses the advantages, in both computation time and memory requirements, of the primal approach over the out‐of‐kilter method. The test environment has the following distinguishing properties: (1) all of the codes are tested on the same machine and the same problems, (2) the test set includes capacitated and uncapacitated transhipment networks, transportation problems, and assignment problems, and (3) problem sizes ranging from 200 to 8,000 nodes with up to 35,000 arcs are examined.
Dynamic network flows with arc changes
Authors: Minieka E.
Published: May 2007

This paper modifies Ford and Fulkerson's Maximum Dynamic Flow Algorithm so that additional arcs can be added to or deleted from the network at a later time period.
Control of an expanding network—“An operational nightmare”
Authors: Mauceri L. J.
Published: May 2007

Control of a network, especially as it expands into new geographic areas, is one of the most important factors in assuring that both the reliability and availability of that network will not be adversely effected.

When the General Electric Company first offered a commercial network as part of its Time‐Sharing service, only a small part of communications control was automated. The remainder of the control functions were performed manually. As the network grew from its infancy into what it is today, it could have become “An Operational Nightmare”.

It became evident that it was necessary to develop into the network a completely automatic control system that would provide operations personnel with the tools for both recognizing and recovering from problems that might compromise either its availability or reliability. Included in this capability are the following:

The ability to detect and display the status of all the nodes.

The ability to detect and display the status of all links.

The ability to introduce new software.

The ability to measure the overall network performance.

The ability to schedule preventive maintenance.

The ability to detect imminent failures.

This paper will show why this automated control system is necessary, how it is structured to record the pulse and heart‐beat of the network and finally how it is used to maintain the stability of the network.
An algorithm for nonlinear multicommodity flow problems
Authors: Klessig R. W.
Published: May 2007

A nonlinear programming algorithm is applied to multicommodity flow problems with nonlinear costs. The algorithm can handle a wide class of problems and unifies several seemingly diverse approaches previously published. Significant computational simplifications that occur under special conditions are discussed.
Algorithms on circular‐arc graphs
Authors: Gavril F.
Published: May 2007

Consider a finite family of non‐empty sets. The intersection graph of this family is obtained by representing each set by a vertex, two vertices being connected by an edge if and only if the corresponding sets intersect. The intersection graph of a family of arcs on a circularly ordered set is called a circular‐arc graph. In this paper we give a characterization of the circular‐arc graph and we describe efficient algorithms for recognizing two subclasses. Also, we describe efficient algorithms for finding a maximum independent set, a minimum covering by cliques and a maximum clique of a circular‐arc graph.
On the optional hamiltonian completion problem
Authors: Slater P. J. , Goodman S. E. , Hedetniemi S. T.
Published: May 2007

The Optional Hamiltonian Completion Problem is defined as follows: let the points V of a graph G be partitioned into a set V0 of optional points and a set V1 of non‐optional points; determine the minimum number of new lines which when added to G result in a graph which has a cycle containing every point of V1. This cycle may or may not contain optional points of V0. In this paper we present algorithms for solving this problem for trees, unicyclic graphs and cacti.
Generalized networks: Networks embedded on a matroid, part I
Authors: Bruno J. , Weinberg L.
Published: May 2007

The definition of ordinary electric networks is based on graphs. Since such a formulation is inadequate in many respects, we define a new network concept, namely, a generalized network, which is a network based on a matroid. To make the paper self‐contained an introduction to basic matroid theory is given in the first part of the paper. We then define a generalized network and formulate the network analysis and network synthesis problems for generalized networks. A number of new results are obtained for both analysis and synthesis and some old results for networks on graphs are generalized to networks on matroids. It is shown that the principle of duality, which does not hold for networks on graphs but is valid for generalized networks, adds power and insight for solving analysis and synthesis problems. The analysis problem, though formulated in terms of resistance networks, holds for networks containing all types of elements. The synthesis problem that is treated is the crucial one of the realization of a p‐port resistance network.
Low cost drainage networks
Authors: Lee D. H.
Published: May 2007

An approach to reducing the cost of drainage networks, such as plumbing networks in buildings, is described. The drain design problem is modelled as a specialized mathematical network called a drainage network; it is shown to be related to the Steiner problem in a directed graph. A procedure which yields a good approximation to the minimum cost drainage network is described. The theoretical solution is implemented in practice via an interactive computer routine which allows for the network to be fitted to the real building. Examples of the application of the approach are given.
A primal algorithm for solving a capacitated network flow problem with additional linear constraints
Authors: Chen S. , Saigal R.
Published: May 2007

A variant of the revised simplex method is given for solving capacitated network flow problems with additional linear constraints. The mathematical development, computer implementation and computational experience are presented. The algorithm described uses a working basis of size equal to the number of additional linear constraints for pivoting, pricing, and inversion, which for large networks, can result in a substantial reduction of computation over a standard linear programming approach.
Implementing vehicle routing algorithms
Authors: Golden B. L. , Magnanti T. L. , Nguyen H. Q.
Published: May 2007

Heuristic programming algorithms frequently address large problems and require manipulation and operation on massive data sets. The algorithms can be improved by using efficient data structures. With this in mind, we consider heuristic algorithms for vehicle routing, comparing techniques of Clarke and Wright, Gillett and Miller, and Tyagi, and presenting modifications and extensions which permit problems involving hundreds of demand points to be solved in a matter of seconds. In addition, a multi‐depot routing algorithm is developed. The results are illustrated with a routing study for an urban newspaper with an evening circulation exceeding 100,000.
A statistical approach to the tsp
Authors: Golden B. L.
Published: May 2007

This paper is an example of the growing interface between statistics and mathematical optimization. A very efficient heuristic algorithm for the well‐known NP‐complete TSP is presented, from which statistical estimates of the optimal tour length can be derived. Assumptions, along with computational experience and conclusions are discussed.
Tree decomposition algorithm for large networks
Authors: Blewett W. J. , Hu T. C.
Published: May 2007

Decomposition algorithms have been proposed for finding the shortest paths between all pairs of nodes in a large network. The central idea is to treat the large network as several small networks overlapping each other. When the small networks overlap each other linearly, algorithms have been proposed to treat each small network individually. The present note treats the case of small networks overlapping each other like a tree.
Unimodular matrices of flow problems with additional constraints
Authors: Truemper K.
Published: May 2007

A graph‐theoretic characterization of unimodular matrices arising from flow problems with additional constraints is developed. The resulting necessary and sufficient conditions are utilized to determine the class of unimodular matrices of multicommodity transportation problems.
Cost allocation for steiner trees
Authors: Megiddo N.
Published: May 2007

A set of points, called consumers, and another point called central supplier, are located in a Euclidean plane. The cost of constructing a connection between two points is proportional to the distance between them. The minimum cost required for connecting all the consumers to the supplier is given by a minimal Steiner tree. An example is given in which for every allocation of the total cost of the tree to the consumers, a coalition of consumers exists, which is charged more than the cost required for connecting its members to the central supplier.
Unicyclic realizability of a degree list
Authors: Boesch F. T. , Harary F.
Published: May 2007

Simple necessary and sufficient conditions for a list of integers to be the degrees of the points of a tree are wellknown. Unicyclic graphs, which are connected graphs with exactly one cycle, are considered here. A simple set of necessary and sufficient conditions for a list of integers to be the degrees of the points of such a graph is derived.
A recognition algorithm for the total graphs
Authors: Gavril F.
Published: May 2007

A graph H is called total if there exists a graph G such that there is a one‐to‐one correspondence between the vertices of H and the vertices and edges of G such that two vertices of H are adjacent iff the corresponding elements of G are adjacent or incident.

In this paper we present a linear time algorithm for the recognition of the total graphs. The algorithm is based on the breadth‐first search technique.
A generalized measure of independence and the strong product of graphs
Authors: Barnes B. H. , Mackey K. E.
Published: May 2007

This work extends the results of M. Rosenfeld [6] on universal graphs with respect to the strong graph product. By using a generalized measure of independence, one can get improved bounds on the growth of the maximum independent set size under this graph product. Furthermore, a necessary and sufficient condition is derived for when the maximum independent set of the product graph is strictly greater than the product of the maximum independent sets.
Generalized ramsey theory for graphs VII: Ramsey numbers for multigraphs and networks
Authors: Harary F. , Schwenk A. J.
Published: May 2007

Ramsey problems are examined for the different varieties of graphs and digraphs, with and without loops and multiple edges, and even for networks. In every case, the resulting Ramsey number either fails to exist, or has a trivial value, or equals the value for the underlying graph or digraph. Thus it appears there are no new interesting Ramsey numbers for multigraphs and networks.
The complexity of the network design problem
Authors: Johnson D. S. , Lenstra J. K. , Kan A. H. G. Rinnooy
Published: May 2007

In the network design problem we are given a weighted undirected graph. We wish to find a subgraph which connects all the original vertices and minimizes the sum of the shortest path weights between all vertex pairs, subject to a budget constraint on the sum of its edge weights. In this note we establish NP‐completeness for the network design problem, even for the simple case where all edge weights are equal and the budget restricts the choice to spanning trees. This result justifies the development of enumerative optimization methods and of approximation algorithms, such as those described in a recent paper by R. Dionne and M. Florian.
On cycle bases of a graph
Authors: Sysło M. M.
Published: May 2007

The paper deals with bases of the vector space associated with a graph. Section 2 presents two characterizations of the cycle basis which can be derived from a spanning tree of a graph, and Section 3 contains the counterexamples for the conjecture of Dixon and Goodman. Finally, some new problems are posed.
Complexity of the minimum‐dummy‐activities problem in a pert network
Authors: Krishnamoorthy M. S. , Deo N.
Published: May 2007

Any complex project consists of a number of activities which are carried out in some specified precedence order. One of the factors that is considered is in minimizing the project completior, time. The computation of the optimum project completion time is proportional to the number of edges, including dummy activities. In the past, many algorithms were proposed to yield minimum number of dummy activities required to satisfy the given precedence relation. In this paper we transform the node‐cover problem in graphs of degree at most 3 to the minimum‐dummy‐activities problem. Using this transformation we show that the minimum‐dummy‐activities problem in a PERT network is NP‐complete. The significance of this result is that it is worthwhile in developing a polynomial time heuristic algorithm for solving the dummy activities problem.
A stochastic petri net with applications to modelling occupancy times for concurrent task systems
Authors: Shapiro Stephen D.
Published: May 2007

A random Petri net model is presented and analyzed. The model has application to systems involving concurrency.
Minimum‐time line broadcast networks
Authors: Farley Arthur M.
Published: May 2007

Broadcasting refers to the process of message dissemination in a communication network whereby a message, originated by one member, becomes known to all members. Line broadcasting assumes that members may “switch‐through” any number of calls during a time unit. An algorithm is presented which produces a calling schedule completing line broadcasting in minimum time from any member of any tree. A discussion of three types of broadcasting and their associated minimum time networks is included.
A theorem concerning cyclic directed graphs with applications to network reliability
Authors: Willie Randall R.
Published: May 2007

In a recent paper, Satyanarayana and Prabhakar have presented a new topological formula for evaluating exact reliability of terminal‐pair directed networks. Terms in the formula are associated in a one‐to‐one fashion with certain acyclic subgraphs of the network, cyclic subgraphs being of no importance. In their paper, however, the proof that cyclic subgraphs may be ignored seems to be incomplete. We consider an alternate proof of this fact.