bluuebunny/crossref_metadata_2025 huggingface dataset:
The Upper Miocene Lake Pannon marl from the Filijala Open Pit (Beocin, northern Serbia): New geological and paleomagnetic data
Authors: Ganic Meri , Rundic Ljupko , Knezevic Slobodan , Cvetkov Vesna
Published: January 2011

This work presents major lithological, structural, paleontological and
paleomagnetic characteristics of the Upper Miocene Pannonian marl in the
Filijala Open Pit of the La Farge Cement Plant near Beocin, northern Serbia.
Pannonian marl lies between the underlying heterogeneous Sarmatian deposits
and the overlying set of Pontian sand beds and Quaternary sediments. The open
pit is located on the NE range of Fruska Gora, a horst structure with a core
of Paleozoic, Mesozoic and Paleogene rocks in a complex structural pattern.
Pannonian sediments, which are part of a younger structural stage, deposited
on the horst limbs. The Pannonian marl strata dip at angles from 12? to 26?
(to the NNW), forming a monocline. The strata deformations are a consequence
of radial tectonics and are a potential source of landslides. The many
mollusks (7 gastropod and 9 bivalve species) and ostracodes (27 species) and
their biostratigraphical position indicate marl deposition throughout the
Pannonian age. A paleomagnetic investigation established that the marl has
inconsistent remanent magnetization (with bad statistical parameters), which
originates from neoformed magnetite.
The peculiarities of electrochemical deposition and morphology of ZnMn alloy coatings obtained from pyrophosphate electrolyte
Authors: Bucko Mihael , Stevanovic Sanja , Tomic Milorad , Pavlovic Miomir , Bajat Jelena
Published: January 2011

The first successful attempt to electrodeposit ZnMn alloy coatings from
alkaline bath was made only a few years ago. In this kind of solution,
potassium pyrophosphate (K4P2O7) serves both as a complexing agent and as the
basic electrolyte. The aim of this work was to study the electrodeposition
process and properties of ZnMn alloy coatings deposited from pyrophosphate
solution, with a new kind of alkaline pyrophosphate bath. Namely, chloride
salts were used as the source of metal ions and ascorbic acid was used as
reducing agent. The composition of the plating solution was as follows: 1 mol
dm-3 K4P2O7 + 0.017 mol dm-3 ascorbic acid + 0.05 mol dm-3 ZnCl2 + 0.05 mol
dm-3 MnCl2?4H2O. Cathodic processes during the alloy electrodeposition were
investigated using linear voltammetry. The influence of addition of small
amounts of ascorbic acid on the cathodic processes was established. It was
shown that this substance inhibits hydrogen evolution and increases the
current efficiency of alloy deposition. The current efficiency in the plating
bath examined was in the range of 25 and 30%, which was quite higher as
compared to the results reported in the literature for electrodeposition of
ZnMn alloy from pyrophosphate bath. Electrodeposition of ZnMn alloys was
performed galvanostatically on steel panels, at current densities of 20120 mA
cm-2. The coatings with the best appearance were obtained at current
densities between 30 and 80 mA cm-2. The surface morphology studies, based on
atomic force microscopy measurements, showed that morphology of the deposits
is highly influenced by deposition current density. ZnMn coating deposited at
30 mA cm-2 was more compact and possessed more homogeneous structure (more
uniform agglomeration size) than the coating deposited at 80 mA cm-2. Such
dependence of morphology on the current density could be explained by the
high rate of hydrogen evolution reaction during the electrodeposition
process.
Water moss as a food item of the zoobenthos in the Yenisei River
Authors: Kalachova Galina , Gladyshev Michail , Sushchik Nadezhda , Makhutova Olesia
Published: January 2011

Bryophytes are abundant in streams and are a habitat for many invertebrates, but their contribution to the diet of fluvial zoobenthos is still debated. To estimate the amount of bryophyte-derived organic matter assimilated by benthic invertebrates, we used a combination of fatty acid and stable isotope analyses during a four-year monthly study of a littoral site in the Yenisei River (Siberia, Russia). Acetylenic acids, which are highly specific biomarkers of the water moss Fontinalis antipyretica, were found in lipids of all dominant benthic animals: gammarids, ephemeropterans, chironomids and trichopterans. The dominant zoobenthic species, Eulimnogammarus viridis, had maximum levels of the biomarkers in its biomass during winter, and minimum levels in summer. The zoobenthos in the studied site regularly consume and assimilate bryophyte-derived organic matter as a minor supplemental food. This consumption increases in winter, when the main food source of the zoobenthos, epilithic biofilms, are probably scarce.
Transcranial magnetic stimulation and extradural electrodes implanted on secondary auditory cortex for tinnitus suppression
Authors: De Ridder Dirk , Vanneste Sven , Kovacs Silvia , Sunaert Stefan , Menovsky Tomas , van de Heyning Paul , Moller Aage
Published: January 2011

Object

Tinnitus is a prevalent symptom, with clinical, pathophysiological, and treatment features analogous to pain. Noninvasive transcranial magnetic stimulation (TMS) and intracranial auditory cortex stimulation (ACS) via implanted electrodes into the primary or overlying the secondary auditory cortex have been developed to treat severe cases of intractable tinnitus.

Methods

A series of 43 patients who benefited transiently from 2 separate placebo-controlled TMS sessions underwent implantation of auditory cortex electrodes. Targeting was based on blood oxygen level–dependent activation evoked by tinnitus-matched sound, using functional MR imaging–guided neuronavigation.

Results

Thirty-seven percent of the patients responded to ACS with tonic stimulation. Of the 63% who were nonresponders, half benefited from burst stimulation. In total, 33% remained unaffected by the ACS. The average tinnitus reduction was 53% for the entire group. Burst stimulation was capable of suppressing tinnitus in more patients and was better than tonic stimulation, especially for noise-like tinnitus. For pure tone tinnitus, there were no differences between the 2 stimulation designs. The average pure tone tinnitus improvement was 71% versus 37% for noise-like tinnitus and 29% for a combination of both pure tone and noise-like tinnitus. Transcranial magnetic stimulation did not predict response to ACS, but in ACS responders, a correlation (r = 0.38) between the amount of TMS and ACS existed. A patient's sex, age, or tinnitus duration did not influence treatment outcome.

Conclusions

Intracranial ACS might become a valuable treatment option for severe intractable tinnitus. Better understanding of the pathophysiological mechanisms of tinnitus, predictive functional imaging tests, new stimulation designs, and other stimulation targets are needed to improve ACS results.
Economic impact of comorbidities in spine surgery
Authors: Walid M. Sami , Robinson Joe Sam
Published: January 2011

Object

Comorbidities in patients undergoing spine surgery may reasonably be factors that increase health care costs. To verify this hypothesis, the authors conducted the following study.

Methods

Major comorbidities and age-adjusted Charlson Comorbidity Index scores were retrospectively analyzed for 816 patients who underwent spine surgery at the authors' institutions between 2005 and 2008, and treatment costs (hospital charges) were assessed with the help of statistical software. The sample was collected by a nonmedical staff (hired at the beginning of 2006). Patients underwent one of the three most common types of spine surgery: lumbar microdiscectomy (20.5%), anterior cervical decompression and fusion (ACDF; 60.3%), or lumbar decompression and fusion (LDF; 19.2%). Patients were nearly equally divided by sex (53% were female and 47% male), and 78% were Caucasian versus 21% who were African American; the rest were of mixed or unidentified race. The average age was 54 years, with an SD of ± 14 years.

Results

There were significant differences in the prevalence of major comorbidities between male and female and between severely obese and nonseverely obese patients. The impact of comorbidities on the cost of spine surgery was more prominent in older patients, and an additive effect from some comorbidities was recorded in various types of spine surgery. For instance, in the ACDF group, female patients with both severe obesity and diabetes mellitus (DM) had significantly higher hospital charges than those with only one or neither of these conditions ($34,943 for both severe obesity and DM vs $25,633 for severe obesity only; $25,826 for DM only; and $25,153 for those with neither condition [p < 0.05]). In the LDF group, female patients with both DM and a history of depression had significantly higher hospital charges than those with only one or neither of these conditions ($65,782 for both DM and depression vs $53,504 for DM only; $55,990 for depression only; and $52,249 for those with neither condition [p < 0.05]). A significant difference was also found in hospital cost ($16,472 [p < 0.01]; 32% increase over baseline) in the LDF group between patients with the lowest and highest scores on the Charlson Index.

Conclusions

Comorbidities additively increase hospital costs for patients who undergo spine surgery, and should be considered in payment arrangements.
Impact of temozolomide chemotherapy on seizure frequency in patients with low-grade gliomas
Authors: Sherman Jonathan H. , Moldovan Krisztina , Yeoh H. Kwang , Starke Robert M. , Pouratian Nader , Shaffrey Mark E. , Schiff David
Published: January 2011

Object

Seizures occur in approximately 80% of patients with low-grade gliomas (LGGs). The majority of patients are treated with anticonvulsant monotherapy; however, many patients require multidrug therapy, or their seizures are refractory to antiepileptic drugs altogether. The oral alkylating agent temozolomide has emerged as a potential initial treatment option for LGG. A few reports suggest an association between temozolomide and reduced seizure frequency in patients with intractable epilepsy.

Methods

Using their clinical database, the authors identified adult patients whose LGGs were treated using temozolomide as the initial antineoplastic therapy at the University of Virginia Health System. As a control group, the authors assessed patients whose LGGs were under observation. All patients had seizure disorders that were treated with anticonvulsants. Seizure frequency in patients with intractable epilepsy was analyzed before and after treatment with temozolomide. Age at diagnosis, sex, antiepileptic drugs, pathological subtype, surgical treatment, and follow-up until progression were also assessed. Interval seizure frequency was meticulously analyzed at each neurooncology clinic visit. A meaningful difference in seizures was defined as a reduction in seizure frequency of greater than 50% per month.

Results

Thirty-nine patients were identified in the temozolomide cohort and 30 patients in the control cohort. The median age at diagnosis was 46 years for the former cohort and 41.5 years for the latter. The median length of follow-up was 39 months for the temozolomide group and 37 months for the control group. There was a significant difference in reduced seizure frequency between patients receiving temozolomide (59%) and those who did not receive temozolomide (13%, p < 0.001). Seven patients (18%) in the temozolomide group displayed this improvement independent of antiepileptic drug adjustment compared with no patient in the control group (p < 0.001).

Conclusions

The authors' data suggest that a subset of patients with LGGs experience improvement in seizure frequency during treatment with temozolomide independent of antiepileptic drug adjustment. This decrease in seizure frequency appears independent of the natural history of seizures in patients whose tumors are under observation. Consequently, seizures in patients with LGGs may be better controlled with the combination of AEDs and temozolomide.
Cortical ependymoma: an unusual epileptogenic lesion
Authors: Van Gompel Jamie J. , Koeller Kelly K. , Meyer Fredric B. , Marsh W. Richard , Burger Peter C. , Roncaroli Federico , Worrell Gregory A. , Giannini Caterina
Published: January 2011

Object

Supratentorial cortical ependymomas (CE) are rare, with 7 cases reported. The lesions, typically occurring in the superficial cortex in young adults and associated with a history of seizures, are not fully characterized. Furthermore, their relationship with the recently described angiocentric glioma (AG) is still being debated. This study was undertaken to summarize the authors' experience with CEs.

Methods

Between 1997 and 2009, 202 cases of ependymoma were surgically treated at the Mayo Clinic, 49 of which were supratentorial. Among these, 9 CE cases were retrospectively identified. Clinical, imaging, and pathological features of each case were reviewed.

Results

Tumors arose from the frontal (5 cases), parietal (3), and occipital (1) lobes. No tumor occurred in the temporal lobe, despite its reported association with seizures. The mean age at presentation was 27 ± 19 years (± SD) and age at resection was 36 ± 16 years. The mean size of the lesion was 16 ± 14 cm3. Seizures were the presenting symptom in 78%. Cross-sectional imaging in 8 cases was characterized by a heterogeneous mass with multiple cystlike areas and enhancement of the soft-tissue component. Gross-total resection was achieved in 8 of 9 tumors. Pathologically, 6 were low-grade (WHO Grade II) and 3 were anaplastic (WHO Grade III) ependymomas. All tumors exhibited the focal presence of perivascular pseudorosettes, but only 1 (11%) exhibited the focal presence of a true rosette. A bipolar spindle cell component resembling AG was present in 3 (33%) and “Schwannian-like” nodules in 2 (22%). Subpial aggregation and peripheral infiltration were present in 4 cases (44%). With a mean postsurgery follow-up of 62 ± 38 months, only 2 lesions recurred locally after imaging-confirmed gross-total resection, both being Grade III. In 5 (71%) of 7 patients presenting with seizures an Engel Class I outcome was achieved.

Conclusions

Cortical ependymomas represent a rare type of ependymoma occurring superficially in the cortex. Morphologically, these tumors are protean, varying from classic to epithelioid, clear cell, and tanycytic. Some also exhibited features typical of AG. Most tumors were low grade and cured with resection. Anaplastic tumors occur and may recur locally despite provision of radiation therapy. Cortical ependymomas frequently, but not always, present with seizures, but despite their high association with epilepsy, none occurred in the temporal lobe in any of the authors' 9 patients. Overall, CEs appear to have a relatively favorable prognosis compared with other supratentorial ependymomas.
Establishment of optimal conditions for an Agrobacterium-mediated transformation in four tomato (Lycopersicon esculentum Mill.) varieties grown in Bangladesh
Authors: Islam Aparna , Chowdhury Jebunnesa , Seraj Zeba I
Published: January 2011

An efficient transformation protocol for tomato by reducing complexity and increasing transformation efficiency in four varieties namely, Bina tomato-3, Bina tomato-5, Bahar and Pusa Ruby. Transformation of cotyledonary leaf explant was performed with Agrobacterium tumefaciens strain LBA4404, harboring binary vector pBI121 having GUS and nptII marker genes. Frequency of transient GUS expression showed that the transformation competence in tomato was highly influenced by several factors, like optical density of Agrobacterium suspension, incubation period, co-cultivation period etc. In the present study, cotyledonary leaf explant from all four tested varieties found to be efficiently transformed by bacterial suspension having optical density (OD600) of 0.79 with 15 min incubation and 3 days of co-cultivation period. All these conditions along with pre-culture of explants prior to transformation gave better regeneration response following Agrobacterium infection. Moreover, for successful regeneration of transformed shoot 200 mg/l kanamycin was found to be most effective selection pressure. As all four varieties showed similar response the present protocol can be considered as a simple and genotype-independent reproducible protocol. Key words: Solanaceae; Transformation parameter; GUS expression; Cotyledonary leaf explant DOI: 10.3329/jbas.v34i2.6863Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 171-179, 2010
Pesticidal activity of Smilax zeylanica L. extracts on Cryptolestes pusillus (Schon.) (Coleoptera: Cucujidae)
Authors: Bari MA , Islam W , Khan AR
Published: January 2011

The chloroform and methanolic extracts of Smilax zeylanica L. were assessed for mortality against the adults of flat grain beetle, Cryptolestes pusillus (Schon.) under laboratory conditions by the surface film method. The methanolic extracts caused significantly high (p < 0.001) mortalities than the chloroform extracts. The calculated LD50 values of the chloroform extracts of S. zeylanica on C. pusillus were 71.20, 67.06 and 62.22 μg/cm2 for leaf; 14.49, 11.41 and 7.9 μg/cm2 for stem; and 6.43, 4.67, 2.40 μg/cm2 for root extracts. But the LD50 values of the methanolic extracts were 39.79, 19.39 and 22.06 μg/cm2 for leaf; 14.27, 12.68 and 10.85 μg/cm2 for stem; and 12.58, 5.83 and 4.32 μg/cm2 for root extracts after 24, 48 and 72 hr post-exposure, respectively. Results obtained show the potential of using S. zeylanica extracts for C. pusillus management. Key words: Smilax zeylanica; Pesticidal activity; Cryptolestes pusillus DOI: 10.3329/jbas.v34i2.6867Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 201-203, 2010
Smoking Related Diseases: The Central Role of Monoamine Oxidase
Authors: Rendu Francine , Peoc’h Katell , Berlin Ivan , Thomas Daniel , Launay Jean-Marie
Published: January 2011

Smoking is a major risk factor of morbidity and mortality. It is well established that monoamine oxidase (MAO) activity is decreased in smokers. Serotonin (5-HT), a major substrate for MAO that circulates as a reserve pool stored in platelets, is a marker of platelet activation. We recently reported that smoking durably modifies the platelet 5-HT/MAO system by inducing a demethylation of the MAO gene promoter resulting in high MAO protein concentration persisting more than ten years after quitting smoking. The present data enlarges the results to another MAO substrate, norepinephrine (NE), further confirming the central role of MAO in tobacco use-induced diseases. Thus, MAO could be a readily accessible and helpful marker in the risk evaluation of smoking-related diseases, from cardiovascular and pulmonary diseases to depression, anxiety and cancer. The present review implements the new finding of epigenetic regulation of MAO and suggests that smoking-induced MAO demethylation can be considered as a hallmark of smoking-related cancers similarly to other aberrant DNA methylations.
Effects of the Methanol Extract of Basella alba L (Basellaceae) on Steroid Production in Leydig Cells
Authors: Nantia Edouard Akono , Travert Carine , Manfo Faustin-Pascal T. , Carreau Serge , Monsees Thomas K. , Fewou Moundipa Paul
Published: January 2011

In this study, Leydig cells were purified from 70 day-old Sprague Dawley male rats and incubated with 10 and 100 µg/mL of methanol extract of Basella alba (MEBa) for 4 hours followed by the evaluation of cell viability, steroid (testosterone and estradiol) production, and the level of aromatase mRNA. Results showed that MEBa did not affect Leydig cell viability. At the concentration of 10 µg/mL, MEBa significantly stimulated testosterone and estradiol production (p < 0.01 and p < 0.03, respectively), and enhanced aromatase mRNA level (p < 0.04). These observations suggest that MEBa directly stimulated testosterone, estradiol and aromatase mRNA levels in isolated Leydig cells.
Issues of Sustainability of Coastal Groundwater Resources: Benin, West Africa
Authors: Silliman Stephen E. , Borum Brian I. , Boukari Moussa , Yalo Nicaise , Orou-Pete Salifou , McInnis Daniel , Fertenbaugh Chrstyn , Mullen Andrew D.
Published: January 2011

The largest city in Benin, West Africa (Cotonou), is reliant upon groundwater for its public water supply. This groundwater is derived from the Godomey well field which is located approximately 5 Km north of the coast of the Atlantic Ocean and in close proximity to Lake Nokoue—a shallow lake containing water with elevated concentration of chloride and other elements. Historical data indicate increased chloride concentration in a number of wells nearest to the lake, with unknown contribution from groundwater encroachment from the coastal area. Hence, there is substantial interest in better characterizing this groundwater system for the purpose of determining appropriate management practices and degree of sustainability. Among the efforts attempted to date are a series of numerical models ranging from assessment of flow to a recent effort to include density-dependent transport from the lake. In addition, substantial field characterization has been pursued including assessment of shallow water chemistry along the region of the coastal lagoon and border of the lake, characterization of hydraulic response to pumpage in the aquifer system, estimation of the distribution of electrical resistivity with depth along the coastal lagoons, and installation of multi-level piezometers at seven locations in the lake. When integrated across methods, these numerical and field results indicate that the lake remains a primary concern in terms of a source of salinity in the aquifer. Further, the coastal region appears to be more complex than previously suggested and may represent a future source of salt-water encroachment as suggested by current presence of saline waters at relatively shallow depths along the coast. Finally, hydraulic testing suggests that both natural and pumping-based fluctuations in water levels are present in this system. Substantial additional characterization and modeling efforts may provide a significantly greater understanding of the behavior of this complex groundwater system and, thereby, an improved ability to manage the potential for negative impacts from salt-water and anthropogenic contaminants entering this sole source of fresh water for southern Benin.
Accident Precursors and Warning Systems Management: A Bayesian Approach to Mathematical Models
Authors: Paté‐Cornell Elisabeth
Published: January 2011

Observing and recognizing precursors and near misses are essential parts of risk management. Many industries have implemented monitoring programs to that effect. The problem is to decide what to monitor, how to interpret the signal(s), and how to respond given the lead time. This article focuses on a Bayesian (probabilistic) approach to the design of warning systems, which permits addressing the trade‐off between the probabilities of false positives and false negatives. The results can then be used as input in a decision analysis to support system‐wide risk management. Probabilistic risk assessment (PRA) is used here as a fundamental tool that allows identifying and fixing the weakest parts of a system. It is shown how one can update the probability of failure of a system given signals that one of the components or subsystems has deteriorated, and how to use PRA to identify potential precursors. The example of a risk analysis for the tiles of the space shuttle is used to illustrate the identification of the failure modes and the weakest parts of a system, a warning that was ignored at the time of that study, years before the Columbia accident. In the dynamic case, it is shown how to optimize a warning threshold to minimize risks and losses. Finally, it is shown how human and organizational factors can be linked to the risk of system failure and the effectiveness of an organizational warning system.
Alternating Renewal Processes
Authors: Argon Nilay Tanik
Published: January 2011

This article introduces a continuous‐time stochastic process, which is called an
alternating renewal process
, that alternates between two states such as “up” and “down.” We provide the limiting distribution of the process and demonstrate its use by two examples.
An Introduction to Platelet Inventory and Ordering Problems
Authors: Blake John T.
Published: January 2011

Platelets are blood cells that initiate the hemostatic plug that causes blood clot formation. Patients receiving intense chemotherapy or suffering massive bleeding complications require platelet transfusions for the prevention of a potentially fatal hemorrhage. A stable, readily available inventory of platelets is required for the safe and effective delivery of health care.

Since platelets must be kept warm to remain viable, they are subject to bacterial contamination, and thus have a shelf life of between five and seven days. Since platelets have a very limited shelf life and are expensive to collect and produce, outdates are an important practical concern for hospitals and blood system operators. Thus, the platelet inventory problem revolves around identifying policies for ordering and holding platelets such that unit availability is maximized, while ensuring that outdates are minimized.

In this paper we define the platelet inventory problem, survey the existing literature, and provide a discussion of solution approaches.
Application of Operations Research In Amusement Park Industry
Authors: Yildirim Utku
Published: January 2011

In this article, a review of the application of operations research methods in the amusement park industry is provided. Although marketing and strategic management side of the theme park industry has been studied extensively, literature in the field of operations research is limited. Research focuses mainly on capacity management and revenue management; however, there are a few under‐researched but key areas that merit more attention. We identify those areas for future research.
Applying Value of Information and Real Options inR&Dand New Product Development
Authors: Keisler Jeffrey M. , Mang Paul Y.
Published: January 2011

Real options analysis and value of information are related tools that help in guiding staged action in the face of quantifiable risk and uncertainty. Many types of projects involve early investments in the hopes of receiving later payoffs. Classes of projects such as R&D and new product development have received considerable attention in this regard. This article provides an overview of the concepts and literature of real options analysis and its connection to the value of information and decision analysis, and how these relate to such future growth opportunities.

R&D and new product development functions can utilize real options analysis/value of information by understanding factors that influence the value of such growth opportunities for the firm and the organizational capabilities required to realize those opportunities. We illustrate this with one set of factors and capabilities associated with a standard R&D project.

We define aninnovation optionas an opportunity for a firm to realize the commercial potential of a new technology by translating it into a novel product or service. During the course of development, information regarding the technical and market feasibility of a project is revealed. The firm can utilize the accumulated information regarding the potential net benefits of a project before committing partially or completely irreversible resources to commercialize the technology. In its most simple form, innovation projects should be viewed as a sequence of two decisions: a decision to gather information regarding the project's prospects (experimentation stage), followed by a decision to commercialize the project (implementation stage).

A basic two‐stage model illustrates how a firm can maximize the value of its innovation efforts by investing in projects that match its organizational capabilities. First, we identify characteristics that determine the potential option value of an innovation project. We then turn our attention to the firm's capabilities that permit it to exploit high option value opportunities. We specifically investigate a firm'slearning capabilityandabandonment capability. We find that an appropriate fit between project and the firm's characteristics will permit the firm to effectively appropriate the option value associated with its innovation opportunities. We contend that firms that are endowed with projects that tend to have high potential option value can improve their innovation processes by investing in the firm's capabilities that allow them to exploit their opportunities. On the other hand, firms that are endowed with projects that have low potential option value may be better off shedding potentially expensive, but relatively valueless, capabilities. Firms that recognize real options can analyze them, and then focus their efforts on adding value by managing their capabilities to exploit those options.
Approximate Dynamic Programming I: Modeling
Authors: Powell Warren B.
Published: January 2011

The first step in solving a stochastic optimization problem is providing a mathematical model. How the problem is modeled can impact the solution strategy. In this article, we provide a flexible modeling framework that uses a classic control‐theoretic framework, avoiding devices such as one‐step transition matrices. We describe the five fundamental elements of any stochastic, dynamic program. Different notational conventions are introduced, and the types of policies that can be used to guide decisions are described in detail. This discussion puts approximate dynamic programming in the context of a variety of other algorithmic strategies by using the modeling framework to describe a wide range of policies. A brief discussion of model‐free programming is also provided.
Combinatorial Auctions: Complexity and Algorithms
Authors: Bichler Martin
Published: January 2011

In the following, we provide an overview of complexity inherent in the design of combinatorial auctions, and discuss how these challenges are addressed in various combinatorial auction formats.

A combinatorial auction allows bidders to submit bids on bundles of objects and can be considered the pivotal example of a multiple object auctions. They also constitute a paradigmatic problem in algorithmic mechanism design. We provide an overview of both the computational complexity and strategic complexity inherent in the design of such auctions, and discuss how these challenges are addressed in various combinatorial auction formats.
Availability in Stochastic Models
Authors: Mercier Sophie
Published: January 2011

A system is considered, which evolves in time according to a stochastic process. The system state space is divided into up‐ and down‐states and the quantities of interest are the system point and asymptotic availabilities, namely the probabilities that the system is in an up‐state at some finite timetand astgoes to infinity. Different stochastic continuous‐time models and associated tools are presented, such as alternating renewal models, Markov and semi‐Markov models, regenerative and Markov regenerative models, with the corresponding renewal or Markov renewal equations fulfilled by the point availability. Classical limit theorems then allow to derive expressions for the asymptotic availability, which involve the process on a generic (Markov) cycle.
Aviation Safety and Security
Authors: Barnett Arnold
Published: January 2011

Operations research contributes to decision‐making about aviation safety and security in two distinct ways: (i) it quantifies the risk that safety and security threats pose to air travelers and (ii) it facilitates analyses about which measures to reduce aviation risk are most likely to be beneficial. This introductory article illustrates both kinds of contributions, focusing on passenger jet aviation and using data about safety and security over the last fifty years.
BasicCPTheory: Consistency And Propagation (Advanced)
Authors: Bessiere Christian
Published: January 2011

In this article, the constraint propagation in constraint satisfaction problems is described. Essentially, the focus is on the concept of local consistency, which has been widely studied in the community. Also, rules iteration is described. Finally, the concept of global constraint is presented.
BasicCPTheory: Search
Authors: Michel Laurent , Van Hentenryck Pascal
Published: January 2011

Constraint programming (CP) is based on the fundamental idea that the resolution of hard optimization problems is best approached by the combination of a declarative model specification and the writing of a search procedure. The search procedure explores the underlying search space while taking advantage of the pruning derived from the declarative model. The search is a fundamental ingredient to exploit the specificities of problems that are difficult or near impossible to capture through the declarative model. The flexibility it provides lead to marked successes for truly challenging problems in scheduling, bounded program verification, test generation, and distributed systems, to name just a few. This article offers a gentle introduction to search in CP, what it can do, and how it is used.
Two‐Stage Stochastic Integer Programming: A Brief Introduction
Authors: Ahmed Shabbir
Published: January 2011

Stochastic integer programming problems combine the difficulty of stochastic programming with integer programming. In this article, we briefly review some of the challenges in solving two‐stage stochastic integer programming problems, and discuss the research progress toward these challenges.
Basis Reduction Methods
Authors: Pataki Gábor , Tural Mustafa
Published: January 2011

We review lattice based methods to solve integer programming feasibility problems, in particular, the algorithms of Lenstra, and Kannan, and the reformulation methods of Aardal,
et al
. and of Krishnamoorthy and Pataki. The unifying theme in all of them is transforming the problem

urn:x-wiley:9780470400531:media:eorms0093:xm1

where
P
is a polyhedron, into

urn:x-wiley:9780470400531:media:eorms0093:xm2

where the columns of
B
are short, and near orthogonal, that is, they form a reduced basis of the generated lattice, and the choice of
B
and the polyhedron
Q
is specific to each method.

We give simple proofs of the polynomial running time of Lenstra's and Kannan's algorithms under the assumption that the dimension is fixed. We analyze the reformulation methods on knapsack problems with decomposable structure, and more surprisingly, we prove that they solve bounded integer programs with high probability by enumerating only one subproblem.

We include several exercises as well, and we believe that the survey will be suitable to teach a 2–3 class long segment on lattice based methods in a course on Integer Programming.
Batch Arrivals and Service—Single Station Queues
Authors: Jayaraman Raja , Matis Timothy I.
Published: January 2011

Queueing models characterized by bulk (or batch, group) arrivals or service performed in batches of either fixed or variable sizes can be commonly found in models of traffic and transportation, complex computer and telecommunication systems, inventory replenishment systems, and many other real‐life applications. In this article, we study single‐server bulk Markovian queueing models, followed by extensions to general distributions for both arrivals and services. We discuss important performance measures in steady state including waiting time characteristics, stochastic ordering properties, approximations, and bounds. We then review methods commonly employed to extend the study of bulk queueing models to more general systems, and present further reading references.
Computational Pool: AnOR—Optimization Point of View
Authors: Dussault Jean‐Pierre , Landry Jean‐François , Mahey Philippe
Published: January 2011

Computational and robotic pool has received increasing attention over the past few years. The challenges are important. In this survey, we focus on the computational aspect but nevertheless, acknowledge that the robotic aspect is both, very important and very difficult.

Computationally, one may roughly split the tasks into three main aspects: simulation of the physics, execution of the shots, and planning of sequences of shots. We will discuss these aspects from an OR‐optimization point of view. The planning aspect also attracts the interest of the artificial intelligence community, and links between both approaches will be revealed.

We will present the state‐of‐the‐art in this new research area, as well as the obstacles that remain before a computer–robotic system actually challenges a human champion.
Call Center Management
Authors: Mehrotra Vijay , Grossman Thomas A. , Samuelson Douglas A.
Published: January 2011

A call center is an organization where agents of a company talk on the telephone to customers or potential customers. Call centers are a large global industry that relies heavily on operations research techniques. Inbound systems are driven by random customer call arrivals and need to balance cost and service quality. Call centers are managed using 15–60 min time blocks. For each time block, managers need to execute forecasting (using forecasting models), performance estimation (via analytic models or simulation), and staffing (to determine the right number of agents). Managers then execute shift scheduling (to devise shifts that cut across time blocks) and rostering (to assign individual agents to shifts). Outbound systems, which originate calls, face the analytical challenge of determining when to dial the next call. Blended systems allow managers to shift agents between inbound and outbound calls. Call centers present interesting operational trends and research opportunities, and challenging practitioner issues.
Capacity Planning
Authors: Rajagopalan Sampath
Published: January 2011

This article is an introduction to capacity planning and basic models used to support capacity planning and expansion decisions. The importance of making good capacity decisions by firms is described followed by definitions of various measures of capacity. The main elements of capacity decisions such as size, timing, and location of capacity additions are discussed. The impact of flexibility of capacity and the level of automation on a firm's productivity, the nature of capacity decisions as a function of the production processes, and implications of interactions between capacity levels at firms in a supply chain are discussed. Some standard deterministic and stochastic models in the literature for making capacity decisions are presented. A key insight from continuous time deterministic models is that it is optimal to add capacity at equal time intervals under several demand and capacity cost scenarios. A basic stochastic capacity expansion model is provided that can be transformed to a deterministic model with a different discount rate under fairly general conditions on the demand process. Finally, a stochastic programming model and heuristic solution approaches are described—this is a flexible approach to model capacity expansion decisions when there is uncertainty in both demand and other parameters.
Classic Financial Risk Measures
Authors: Novosyolov Arcady
Published: January 2011

The article presents classic methods for measuring financial risk or support decision making under risk, including probability of undesired event, mean value, expected utility, mean‐variance based functionals and value‐at‐risk. Basic concepts are explained using examples and pictures rather than formal definitions. The article concludes with further reading suggestions.
Common Random Numbers
Authors: Schruben Lee W.
Published: January 2011

By far the simplest and most widely used variance reduction technique (VRT) for stochastic simulations is simply to use the same sets of common random number streams (CRNs) to generate random variables when running simulations at different input factor settings. This is the default, or is easily implemented, in many commercial simulation software packages. However, this potentially powerful VRT should be used differently depending on how random variables are generated, how these random variables are used when running the simulation model to generate output data, and how the output data is used in analysis.
Decision Problems and Applications of Operations Research at Marine Container Terminals
Authors: Goodchild Anne , Zhao Wenjuan , Wygonik Erica
Published: January 2011

This article provides an overview of the applications of operations research (OR) techniques to marine container terminals. The article begins by providing a summary of marine container terminal operations. Following this, a series of decision problems are identified, to which OR techniques have been applied. These include quayside, yard, and landside decision problems. In each section, the problems, technical approaches, and outcomes are described. With respect to quayside decision problems, the specific problems addressed include determination of quayside equipment types, berth allocation, quay crane allocation and scheduling, and operational planning and real‐time decisions related to transportation equipment. Yard decision problems include yard design, storage space allocation, and task assignment for yard handling equipment. Landside decision problems include design of the terminal's landside connection, transport planning, and real‐time control of landside operations. The article provides an overview of the state of the practice. The reader will gain an understanding of the nature of decision problems in marine container terminals, how OR techniques have been used to address these, and the operational improvements made possible through the application of OR techniques to this problem area.
Czech Society for Operations Research
Authors: Fiala Petr
Published: January 2011

The article informs about The Czech Society for Operations Research (CSOR). A short history and activities of the CSOR are briefly described. The annual conferences, Mathematical Methods in Economics, are organized by the Czech Society for Operations Research. The main international activity organized by the Czech Society for Operations Research was the 22nd European Conference on Operational Research EURO XXII in 2007.
Descriptive Models of Perceived Risk
Authors: Wang Yitong , Keller L. Robin , Simon Jay
Published: January 2011

This article provides a brief introduction to descriptive models of perceived risk. The first part focuses on monetary risks or any risks whose information can be distilled into payoffs and their probabilities. The second part focuses on psychological research on societal risks such as psychometric models. Some further developments are also included such as cross‐cultural studies and the risk‐as‐feelings hypothesis.
Design and Control Principles of Flexible Workforce in Manufacturing Systems
Authors: Iravani Seyed M. R.
Published: January 2011

Agile (flexible) manufacturing, a natural successor to lean manufacturing, emphasizes customized products, efficiency (as pursued through lean manufacturing and other methods for making more with less), and responsiveness for meeting diverse customer requirements in a prompt and personalized manner. Unlike lean manufacturing, which emphasizes mass production in large‐scale corporate structures, agile manufacturing is better suited to smaller scale and modular flexible production facilities. In this environment, flexible resources such as a flexible (cross‐trained) workforce will become increasingly essential. In this article we show how worker cross‐training can improve the performance of manufacturing systems through capacity balancing and variability buffering. We also present effective design and control principles to utilize the potential benefits of a flexible workforce.
Design Considerations for Supply Chain Tracking Systems
Authors: Dai Hongyan , Tseng Mitchell M. , Monsreal Mario M.
Published: January 2011

Supply chain tracking systems are becoming imperative to help achieve competitive advantages from efficiency and responsiveness improvement, and comply with social awareness of product safety, security, and sustainability. It is important to design the supply chain tracking system in such a way that it can achieve the desired benefits and minimize the costs at the same time. However, there are various challenges to gain this cost effectiveness with regard to technologies, standards, operations, and strategies. Moreover, there are no complete design principles available at this moment. It is the intent of this paper to provide a framework for designing a cost‐effective supply chain tracking system. We will explain the main considerations for a tracking system design and articulate how to coordinate various considerations to reach the optimal design in an economical way. Ultimately, we want to provide some feasible and practical guidelines to support and simplify the decision making process for building supply chain tracking systems.
Design for Manufacturing and Assembly
Authors: Koraishy Babar M. , Wood Kristin L. , Tilstra Andrew
Published: January 2011

Design for manufacturing and assembly (DFMA) represents a strategic approach implemented by enterprises to ensure simultaneous consideration of the manufacturing processes and assemblability of a product or system as the product or system proceeds from conception to installation, implementation, and use. DFMA applies across an enterprise's organization and structure, from multidisciplinary team formation, the establishment of supply chains, activity‐based costing, to manufacturing and assembly infrastructure, process and quality control, and the actual architectural and design choices for a particular product or system. This article will not attempt to cover this broad spectrum. Instead, our focus entails a study of basic design guidelines, tools, and techniques that can be employed by a designer or design team to improve the manufacturing and assembly associated with a product or system. Specifically, we present the basic constructs of design for manufacturing and design for assembly. Using these constructs as a foundation, we explore a set of practical design guidelines as they relate to both manufacturability and assemblability. A basic DFMA technique, known as effort‐flow analysis, is then presented to analyze and improve a product or system. The knowledge gained from the design guidelines and effort–flow analysis can be used to refine a design so that it is easier to fabricate and easier to assemble. Improvements of these types, in turn, can lead to significant cost savings and reduced failure modes. They can also lead to novel and innovative solutions of products and systems at the component level.
Introduction to Discrete‐Event Simulation
Authors: Ingalls Ricki G.
Published: January 2011

Simulation is a powerful tool if understood and used properly. This introduction is designed to teach the basics of simulation, including structure, function, data generated, and its proper use. The introduction starts with a definition of simulation, goes through a discussion about the elements of a simulation, how the simulation actually works, and how to handle data generated by the simulation. Throughout the article, there is discussion on issues concerning the use of simulation in industry.
The Scatter Search Methodology
Authors: Laguna Manuel , Martí Rafael , Gallego Micael , Duarte Abraham
Published: January 2011

Scatter search (SS) is an evolutionary approach for optimization. It has been applied to problems with continuous and discrete variables and with a single or multiple objectives. The success of SS as an optimization technique is well documented in a constantly growing number of journal articles and book chapters. This article first focuses on the basic SS framework, which is responsible for most of the outcomes reported in the literature, and then covers advanced elements that have been introduced in a few selected papers, such as the hybridization with tabu search, a well‐known memory‐based metaheuristic. We consider the maximum diversity problem to illustrate the search elements, methods and strategies described here.