bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of obesity and type 2 diabetes mellitus in the development of male obesity‐associated secondary hypogonadism
Authors: Saboor Aftab S. A. , Kumar S. , Barber T. M.
Published: November 2012

Obesity, secondary (hypogonadotrophic) hypogonadism (SH), sleep disorders [such as obstructive sleep apnoea (OSA)] and type 2 diabetes mellitus (T2DM) in men have complex interlinks both with respect to mutual aetiopathogenesis as well as therapeutics. Correction of the attendant hypogonadism in obese men may serve to break this link and have beneficial effects beyond restoration of normal sexual function. Male obesity‐associated secondary hypogonadism (MOSH) should be regarded as a distinct clinical entity and subtype of SH. A high index of suspicion for the presence of MOSH must be maintained by clinicians when assessing obese men. The pathogenesis of MOSH remains incompletely understood. Furthermore, the optimal management of MOSH and its associated sequelae will require long‐term prospective studies that in turn will inform the development of future clinical guidelines for this important and prevalent condition.
Acoustic rhinometry, rhinomanometry and visual analogue scale before and after septal surgery: a prospective 10‐year follow‐up
Authors: Haavisto L.E. , Sipilä J.I.
Published: November 2012

Objectives

The aim of the study was to compare rhinomanometry, acoustic rhinometry and subjective estimation of the nasal obstruction before and after septoplasty and to evaluate the long‐term results of septal surgery.

Design

Prospective long‐term follow‐up, before and after septoplasty.

Setting

University tertiary‐care hospital, referral centre.

Participants

The study included 30 adult patients who were operated on because of septal deviation.

Main outcome measures

Pre‐operatively, acoustic rhinometry and active anterior rhinomanometry were performed on each subject after decongestion of the nose. A visual analogue scale for unilateral nasal obstruction was filled in by the patients. The measurements were repeated both 6 months and 10 years post‐operatively.

Results

A significant change in acoustic values was found during the long‐term follow‐up of 10 years. The mean minimal cross‐sectional area on the more obstructive side was 0.35 cm2 pre‐operatively. Six months after operation, it was 0.52 cm2, and 10 years after operation, it was 0.68 cm2. The mean resistance fell from pre‐operative 1.16 Pa/mL/s to 0.41 Pa/mL/s during the first 6 months, but rose again to 1.21 Pa/mL/s after 10 years. Despite a tendency of improvement, no statistically significant change was found between pre‐operative and postoperative values in VAS. Six months after operation 69% of the patients were satisfied with the result, and after ten years the amount of satisfied patients was 83%.

Conclusions

We found an increase in acoustic values, but an increase in nasal resistance in the long‐term follow‐up. Other factors than nasal area may have an impact on nasal resistance and the feeling of nasal obstruction. The small size on the sample interfered with the results.
Neural Computation and the Computational Theory of Cognition
Authors: Piccinini Gualtiero , Bahar Sonya
Published: November 2012

We begin by distinguishing computationalism from a number of other theses that are sometimes conflated with it. We also distinguish between several important kinds of computation: computation in a generic sense, digital computation, and analog computation. Then, we defend a weak version of computationalism—neural processes are computations in the generic sense. After that, we reject on empirical grounds the common assimilation of neural computation to either analog or digital computation, concluding that neural computation is sui generis. Analog computation requires continuous signals; digital computation requires strings of digits. But current neuroscientific evidence indicates that typical neural signals, such as spike trains, are graded like continuous signals but are constituted by discrete functional elements (spikes); thus, typical neural signals are neither continuous signals nor strings of digits. It follows that neural computation is sui generis. Finally, we highlight three important consequences of a proper understanding of neural computation for the theory of cognition. First, understanding neural computation requires a specially designed mathematical theory (or theories) rather than the mathematical theories of analog or digital computation. Second, several popular views about neural computation turn out to be incorrect. Third, computational theories of cognition that rely on non‐neural notions of computation ought to be replaced or reinterpreted in terms of neural computation.
Grafting of functional motifs onto protein scaffolds identified by PDB screening – an efficient route to design optimizable protein binders
Authors: Tlatli Rym , Nozach Hervé , Collet Guillaume , Beau Fabrice , Vera Laura , Stura Enrico , Dive Vincent , Cuniasse Philippe
Published: November 2012

Artificial miniproteins that are able to target catalytic sites of matrix metalloproteinases (MMPs) were designed using a functional motif‐grafting approach. The motif corresponded to the four N‐terminal residues of TIMP‐2, a broad‐spectrum protein inhibitor of MMPs. Scaffolds that are able to reproduce the functional topology of this motif were obtained by exhaustive screening of the Protein Data Bank (PDB) using stamps software (search for three‐dimensional atom motifs in protein structures). Ten artificial protein binders were produced. The designed proteins bind catalytic sites of MMPs with affinities ranging from 450 nm to 450 μm prior to optimization. The crystal structure of one artificial binder in complex with the catalytic domain of MMP‐12 showed that the inter‐molecular interactions established by the functional motif in the artificial binder corresponded to those found in the MMP‐14–TIMP‐2 complex, albeit with some differences in geometry. Molecular dynamics simulations of the ten binders in complex with MMP‐14 suggested that these scaffolds may allow partial reproduction of native inter‐molecular interactions, but differences in geometry and stability may contribute to the lower affinity of the artificial protein binders compared to the natural protein binder. Nevertheless, these results show that the in silico design method used provides sets of protein binders that target a specific binding site with a good rate of success. This approach may constitute the first step of an efficient hybrid computational/experimental approach to protein binder design.
Pre‐existing central nervous system lesions negate cytokine requirements for regional experimental autoimmune encephalomyelitis development
Authors: Li Xin , Lees Jason R.
Published: November 2012

In region‐specific forms of experimental autoimmune encephalomyelitis (EAE), lesion initiation is regulated by T‐cell‐produced interferon‐γ (IFN‐γ) resulting in spinal cord disease in the presence of IFN‐γ and cerebellar disease in the absence of IFN‐γ. Although this role for IFN‐γ in regional disease initiation is well defined, little is known about the consequences of previous tissue inflammation on subsequent regional disease, information vital to the development of therapeutics in established disease states. This study addressed the hypothesis that previous establishment of regional EAE would determine subsequent tissue localization of new T‐cell invasion and associated symptoms regardless of the presence or absence of IFN‐γ production. Serial transfer of optimal or suboptimal doses of encephalitogenic IFN‐γ‐sufficient or ‐deficient T‐cell lines was used to examine the development of new clinical responses associated with the spinal cord and cerebellum at various times after EAE initiation. Previous inflammation within either cerebellum or spinal cord allowed subsequent T‐cell driven inflammation within that tissue regardless of IFN‐γ presence. Further, T‐cell IFN‐γ production after initial lesion formation exacerbated disease within the cerebellum, suggesting that IFN‐γ plays different roles at different stages of cerebellar disease. For the spinal cord, IFN‐γ‐deficient cells (that are ordinarily cerebellum disease initiators) were capable of driving new spinal‐cord‐associated clinical symptoms more than 60 days after the initial acute EAE resolution. These data suggest that previous inflammation modulates the molecular requirements for new neuroinflammation development.
Identifying reproductive events using archival tags: egg‐laying behaviour of the small spotted catshark Scyliorhinus canicula
Authors: Wearmouth V. J. , Southall E. J. , Morritt D. , Sims D. W.
Published: November 2012

The use of archival depth telemetry as a means of remotely assessing the reproductive rates of free‐ranging fishes is explored. This is achieved by electronically tracking the vertical movements of individual female small spotted catsharks Scyliorhinus canicula in the natural environment, whilst simultaneously evaluating the temporal and vertical distributions of egg‐laying in this species. Distinctive patterns of short‐term (0·3–3·7 h), shallow‐water activity are documented in the time–depth profiles of female S. canicula that occur at an appropriate depth (1·0–2·3 m) and periodicity (every 10–12 days) to represent egg‐laying behaviour. Putative egg‐laying behaviour was exhibited simultaneously by two individually tracked female S. canicula during late‐spring and early‐summer. The results highlight that, provided species behaviour is suitable and complementary methods such as previous data, laboratory experiments and field surveys can be used to validate the patterns observed, archival depth telemetry offers an unobtrusive means by which egg production and egg‐laying behaviour of free‐living fishes can be estimated. As precise information regarding life‐history parameters is difficult to obtain for free‐ranging fish species, this technique could be used to improve the parameterization of species demographic models that are relevant to the management of wild fish populations.
Silence and Catastrophe: New Reasons Why Politics Matters in the Early Years of the Twenty‐first Century
Authors: KEANE JOHN
Published: November 2012

Megaprojects are systems of highly concentrated power whose footprints, or radius of effects, are without precedent in human history. Once upon a time, even under imperial conditions, most people on our planet lived and loved, worked and played within geographically limited communities. They never had to reckon with all of humanity as a factor in their daily lives. Whenever they acted recklessly within their environment, for instance, they had the option of moving on, safe in the knowledge that there was plenty of Earth and not many others. Whenever bad things happened, they happened within limits. Their effects were local. The politics of megaprojects radically alters this equation; it poses new questions about the governance of risk and the nature and limits of democratic politics. The politics of megaprojects—put simply—raises fundamental questions about the ‘life and death of democracy’.
A Measure of Competition Based on 10‐K Filings
Authors: LI FENG , LUNDHOLM RUSSELL , MINNIS MICHAEL
Published: November 2012

In this paper we develop a measure of competition based on management's disclosures in their 10‐K filing and find that firms’ rates of diminishing marginal returns on new and existing investment vary significantly with our measure. We show that these firm‐level disclosures are related to existing industry‐level measures of disclosure (e.g., Herfindahl index), but capture something distinctly new. In particular, we show that the measure has both across‐industry variation and within‐industry variation, and each is related to the firm's future rates of diminishing marginal returns. As such, our measure is a useful complement to existing measures of competition. We present a battery of specification tests designed to explore the boundaries of our measure and how it varies with the definition of industry and the presence of other measures of competition.
Histopathologic staining of low temperature cutaneous burns: Comparing biomarkers of epithelial and vascular injury reveals utility of HMGB1 and hematoxylin phloxine saffron
Authors: Hirth Douglas A. , Singer Adam J. , Clark Richard A. F. , McClain Steve A.
Published: November 2012

Histopathology remains the gold standard for evaluation of burn depth, progression, and healing, but burn literature offers little guidance on the best stains for analysis of these complex and evolving injuries. A battery of histochemical and immunohistochemical stains was compared on adjacent sections to determine the best stains for histopathologic study and imaging of burns. Using a validated porcine model of vertical burn progression, full‐thickness cutaneous biopsies were stained using hematoxylin and eosin, Hematoxylin phloxine saffron (HPS), Masson Trichrome, Elastin Von Gieson, Movatt's Pentachrome, vimentin, CD31, KI‐67, caspase 3a, and high mobility group box 1. Depth of collagen degeneration, cellular necrosis, apoptosis, and vascular occlusion; and reparative processes of cellular hyperplasia, reepithelialization, and new collagen deposition were measured by ocular microscopy. High mobility group box 1 was superior for necrosis between 1 and 24 hours postburn. Vimentin underestimated necrosis until 48 hours postburn. For overall assessment, hematoxylin and eosin and HPS were comparable, except for analysis of thermally injured collagen, vessel occlusion, erythrocyte extravasation, and polariscopic study of collagen deposition, where HPS was superior. HPS stain offers specific advantages in histopathologic burn analysis. Inexpensive and rapid to produce, HPS allows users to analyze eosinophilic components more precisely than standard hematoxylin and eosin.
Food and Drug Administration (FDA) drug approval end points for chronic cutaneous ulcer studies
Authors: Eaglstein William H. , Kirsner Robert S. , Robson Martin C.
Published: November 2012

The rising costs of caring for chronic cutaneous ulcers (CCUs) and recent appreciation of the mortality of CCUs have led to consideration of the reasons for the failure to have new drug therapies. No new chemical entities to heal CCUs have been approved by the Food and Drug Administration (FDA) in over a decade, in part due to an inability to reach the FDA accepted end point of “complete wound closure.” The frequent failure to reach the complete closure end point brings forward the question of the relevance of other healing end points such as improved quality of life, or partial healing. Because CCUs carry a prognosis and mortality rate worse than many cancers, it is reasonable to compare the FDA trial end points for cancer drug approval with those for CCUs. And the difference is quite striking. While there is only one end point for CCUs, there are five surrogate and three direct end points for cancers. In contrast to cancer, surrogate end points and partial healing are not acceptable for therapies aimed at CCUs. For example, making tumors smaller is an acceptable end point, but making CCUs smaller is not and improvement in the signs and symptoms of cancer is an acceptable end point for cancers but not CCUs. As CCUs carry a prognosis and mortality rate worse than many cancers, we believe a reconsideration of end points for CCUs is highly warranted.
Rethinking tortious immunity for judicial acts
Authors: Murphy John
Published: November 2012

This paper considers the immunity in tort enjoyed by superior court judges in England and Wales. It suggests, first, that the current level of immunity is set too high; secondly, that the reasons traditionally given for this level of immunity are overwhelmingly unconvincing and that, therefore, thirdly, a lesser degree of immunity (which allows judges to be exposed to potential liability under a modified version of the tort of misfeasance in a public office) would be the preferable way to proceed.
Microwave‐Assisted Hydrothermal Synthesis of Submicrometer Willemite Phase Zinc Silicate and Its Zinc Ion Release Behavior
Authors: Xiong Kun , Liu Jingqun , Li Jiyan , Ye Jiandong
Published: November 2012

As an important trace element in human bone, zinc (Zn) has a great influence on bone metabolism. The aim of this work was to prepare a Zn‐containing material that can release Zn ions. For this purpose, submicrometer willemite phase zinc silicate (Zn2SiO4, ZS) with poor crystallinity was synthesized at 110°C via the microwave‐assisted hydrothermal (MH) method. Under the MH condition, the growth of ZS was consistent with “multi‐core growth” mechanism. Moreover, the influences of the reaction temperature and the reactant concentration on the final products were investigated in detail. The inductively coupled plasma atomic emission spectroscopy (ICP) data indicated that the poor crystallinity ZS could successfully release Zn for at least 28 d as soaking in the simulated body fluid (SBF). Without the replenishment of SBF, ~333 μM Zn was released from ZS synthesized at 110°C (ZS‐110). If SBF was periodically replenished once a day, more Zn was released from ZS‐110, and the parascholzite phase calcium zinc phosphate hydrate (CaZn2(PO4)2·2H2O) formed during the soaking process of ZS‐110. Under the concentration of 6.25 mg/mL, the extract of ZS‐110 was proved to be nontoxic by assessing with mouse osteoblast cells (MC3T3). Therefore, the poor crystallinity ZS has potential to be incorporated into the orthopedic reconstructive materials as a source of Zn ions, which can improve the bioactivity of the materials.
Do wild fish species contribute to the transmission of koi herpesvirus to carp in hatchery ponds?
Authors: Fabian M , Baumer A , Steinhagen D
Published: November 2012

The koi herpesvirus (KHV) has spread worldwide since its discovery in 1998 and causes disease and mortality in koi and common carp populations with a high impact on the carp production industry. Many investigations have been conducted to examine ways of distribution and to identify possible transmission vectors. The answers, however, raise many new questions. In the present study, different wild fish species taken from carp ponds with a history of KHV infection were examined for their susceptibility to the virus. In the tissue of these fish, the virus load was determined and it was tested whether a release of the virus could be induced by stress and the virus then could be transferred to naive carp. Wild fish were gathered from carp ponds during acute outbreaks of virus‐induced mortality in summer and from ponds stocked with carp carrying a latent KHV infection. From these ponds, wild fish were collected during the harvesting process in autumn or spring when the ponds were drained. We found that regardless of season, temperature variation, age and infection status of the carp stock, wild fish from carp ponds and its outlets could be tested positive for the KHV genome using real‐time PCR with a low prevalence and virus load. Furthermore, virus transfer to naive carp was observed after a period of cohabitation. Cyprinid and non‐cyprinid wild fish can therefore be considered as an epidemiological risk for pond carp farms.
Vinpocetine and α‐tocopherol prevent the increase in DA and oxidative stress induced by 3‐NPA in striatum isolated nerve endings
Authors: Herrera‐Mundo Nieves , Sitges María
Published: November 2012

Vinpocetine is a neuroprotective drug that exerts beneficial effects on neurological symptoms and cerebrovascular disease. 3‐nitropropionic acid (3‐NPA) is a toxin that irreversibly inhibits succinate dehydrogenase, the mitochondrial enzyme that acts in the electron transport chain at complex II. In previous studies in striatum‐isolated nerve endings (synaptosomes), we found that vinpocetine decreased dopamine (DA) at expense of its main metabolite 3,4‐dihydroxyphenylacetic acid (DOPAC), and that 3‐NPA increased DA, reactive oxygen species (ROS), DA‐quinone products formation, and decreased DOPAC. Therefore, in this study, the possible effect of vinpocetine on 3‐NPA‐induced increase in DA, ROS, lipid peroxidation, and DA‐quinone products formation in striatum synaptosomes were investigated, and compared with the effects of the antioxidant α‐tocopherol. Results show that the increase in DA induced by 3‐NPA was inhibited by both 25 μM vinpocetine and 50 μM α‐tocopherol. Vinpocetine, as α‐tocopherol, also inhibited 3‐NPA‐induced increase in ROS (as judged by DCF fluorescence), lipid peroxidation (as judged by TBA‐RS formation), and DA‐quinone products formation (as judged by the nitroblue tetrazolium reduction method). As in addition to the inhibition of complex II exerted by 3‐NPA, 3‐NPA increases DA‐oxidation products that in turn can inhibit other sites of the respiratory chain, the drop in DA produced by vinpocetine and α‐tocopherol may importantly contribute to their protective action from oxidative damage, particularly in DA‐rich structures.
Rosuvastatin ameliorates high‐fat and high‐cholesterol diet‐induced nonalcoholic steatohepatitis in rats
Authors: Okada Yoshihisa , Yamaguchi Kanji , Nakajima Tomoki , Nishikawa Taichiro , Jo Masayasu , Mitsumoto Yasuhide , Kimura Hiroyuki , Nishimura Takeshi , Tochiki Nozomi , Yasui Kohichiroh , Mitsuyoshi Hironori , Minami Masahito , Kagawa Keizo , Okanoue Takeshi , Itoh Yoshito
Published: November 2012

Background/Aims

Statins, which are inhibitors of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase and inhibit endogenous cholesterol synthesis, possess pleiotropic activities, such as anti‐inflammatory, anti‐oxidative and antifibrotic effects. Here, we investigated whether statins ameliorate steatohepatitis using a high‐fat and high‐cholesterol (HFHC) diet‐induced rat model.

Methods

Eight‐week‐old male Sprague–Dawley rats were fed control chow or HFHC diet. Half of the HFHC diet‐fed rats were orally administered 2 mg/kg/day rosuvastatin for 12 weeks. Hepatic injury, steatosis, fibrosis and markers of lipid peroxidation/oxidant stress were evaluated.

Results

As previously reported, HFHC diet induced steatohepatitis in rat livers with hypercholesterolaemia. Rosuvastatin decreased Oil Red O stained‐positive areas, liver/body weight ratio, serum total cholesterol levels and hepatic free fatty acid contents in HFHC diet‐fed rats. Further study revealed that rosuvastatin significantly decreased hepatic mRNA expression of tumour necrosis factor‐α and interleukin‐6, serum alanine aminotransferase levels and hepatic lobular inflammation grade. Hepatic fibrosis was also ameliorated by rosuvastatin with decreases in hepatic mRNA expression of transforming growth factor‐β, connective tissue growth factor and type‐1 procollagen. Similarly, hepatic Sirius red stained or α‐smooth muscle actin stained‐positive areas and expression of markers of lipid peroxidation/oxidant stress [hepatic 8‐hydroxy‐oxyguanosine and hepatic 4‐hydroxy‐2‐nonenal] were decreased. Interestingly, whereas the expression of carnitine palmitoyltransferase‐1 and long‐chain acyl‐CoA dehydrogenase was not affected, that of catalase and acyl‐coA oxidase was restored.

Conclusions

These data suggest that rosuvastatin improved not only hepatic steatosis but also hepatic injury and fibrosis via improved peroxisomal β‐oxidation in this rat HFHC model.
Genotype matching in a parasitoid–host genotypic food web: an approach for measuring effects of environmental change
Authors: Lavandero Blas , Tylianakis Jason M.
Published: November 2012

Food webs typically quantify interactions between species, whereas evolution operates through the success of alleles within populations of a single species. To bridge this gap, we quantify genotypic interaction networks among individuals of a single specialized parasitoid species and its obligate to cyclically parthenogenetic aphid host along a climatic gradient. As a case study for the kinds of questions genotype food webs could be used to answer, we show that genetically similar parasitoids became more likely to attack genetically similar hosts in warmer sites (i.e. there was network‐wide congruence between the within‐species shared allelic distance of the parasitoid and that of its host). Narrowing of host‐genotype‐niche breadth by parasitoids could reduce resilience of the network to changes in host genetic structure or invasion by novel host genotypes and inhibit biological control. Thus, our approach can be easily used to detect changes to sub‐species‐level food webs, which may have important ecological and evolutionary implications, such as promoting host‐race specialization or the accelerated loss of functional diversity following extinctions of closely related genotypes.
Mutations in the SLAC1 anion channel slow stomatal opening and severely reduce K+ uptake channel activity via enhanced cytosolic [Ca2+] and increased Ca2+ sensitivity of K+ uptake channels
Authors: Laanemets Kristiina , Wang Yong‐Fei , Lindgren Ove , Wu Juyou , Nishimura Noriyuki , Lee Stephen , Caddell Daniel , Merilo Ebe , Brosche Mikael , Kilk Kalle , Soomets Ursel , Kangasjärvi Jaakko , Schroeder Julian I. , Kollist Hannes
Published: November 2012

The Arabidopsis guard cell anion channel SLAC1 is essential for stomatal closure in response to various endogenous and environmental stimuli. Interestingly, here we reveal an unexpected impairment of slac1 alleles on stomatal opening.

We report that mutations in SLAC1 unexpectedly slow stomatal opening induced by light, low CO2 and elevated air humidity in intact plants and that this is caused by the severely reduced activity of inward K+ (K+in) channels in slac1 guard cells.

Expression of channels and transporters involved in stomatal opening showed small but significant reductions in transcript levels in slac1 guard cells; however, this was deemed insufficient to explain the severely impaired K+in channel activity in slac1. We further examined resting cytosolic Ca2+ concentration ([Ca2+]cyt) and K+in channel sensitivity to [Ca2+]cyt in slac1. These experiments showed higher resting [Ca2+]cyt in slac1 guard cells and that reducing [Ca2+]cyt to < 10 nM rapidly restored the activity of K+in channels in slac1 closer to wild‐type levels.

These findings demonstrate an unanticipated compensatory feedback control in plant stomatal regulation, which counteracts the impaired stomatal closing response of slac1, by down‐regulating stomatal opening mechanisms and implicates enhanced [Ca2+]cyt sensitivity priming as a mechanistic basis for the down‐regulated K+in channel activity.
Win–Win–Win: The Influence of Company‐Sponsored Volunteerism Programs on Employees, NGOs, and Business Units
Authors: Caligiuri Paula , Mencin Ahsiya , Jiang Kaifeng
Published: November 2012

Although the number of firms adopting corporate volunteerism programs is rising steadily, very few firms are assessing the benefits of such programs on target groups, such as employees and nongovernmental organizations (NGOs), and identifying the conditions under which benefits to the various groups are maximized. This study addresses both by examining the conditions of employees’ corporate volunteer assignments that lead to increased employee engagement, sustainability of the volunteers’ project within the NGO, capability development for the business unit, and employees’ continuation of volunteerism. Using a longitudinal and multisource design, responses from 116 corporate volunteers from a global pharmaceutical organization are matched with responses from their NGO managers and their business unit managers at 3 points in time: at the start of the volunteer assignment, at the end of the assignment, and 6 months after the completion of the assignment. Across these outcomes, we found that employees’ volunteer assignments are most valuable when they are international, when the volunteers perceive that their projects contribute meaningfully the NGO's functioning, when volunteers have professional skills (and are able to use them), when there are opportunities for skills to be developed that can be applied in the volunteers’ regular work role, and when the NGOs have tangible resources to sustain the volunteers’ projects.
Balancing Treatment and Control Groups in Quasi‐Experiments: An Introduction to Propensity Scoring
Authors: Connelly Brian S. , Sackett Paul R. , Waters Shonna D.
Published: November 2012

Organizational and applied sciences have long struggled with improving causal inference in quasi‐experiments. We introduce organizational researchers to propensity scoring, a statistical technique that has become popular in other applied sciences as a means for improving internal validity. Propensity scoring statistically models how individuals in a quasi‐experiment have been assigned to conditions in order to estimate treatment effects among individuals with approximately equal probabilities of receiving the treatment. If propensity scores are created from relevant covariates, matching on the propensity score makes treatment assignment ignorable and approximates a true experimental design. We illustrate how matching on the propensity score can be applied by using 2 examples: examining the effects of online instruction and estimating the benefits of preparatory coaching for the SAT. In both cases, propensity‐scoring methods effectively reduced inequivalence between treatment and control groups on many variables. Propensity scoring stands out as a valuable technique capable of improving causal inference from many of organizational research's quasi‐experiments.
Selection of Sensors for Hydro-Active Suspension System of Passenger Car With Input–Output Pairing Considerations
Authors: Sarshari Ehsan , Sedigh Ali Khaki
Published: November 2012

With respect to weight, energy consumption, and cost constraints, hydro-active suspension system is a suitable choice for improving vehicle ride comfort while keeping its handling. The aim of sensors selection is determining number, location, and type of sensors, which are the best for control purposes. Selection of sensors is related to the selection of measured variables (outputs). Outputs selection may limit performance and also affect reliability and complexity of control systems. In the meanwhile, hardware, implementation, maintenance, and repairing costs can be affected by this issue. In this study, systematic methods for selecting the viable outputs for hydro-active suspension system of a passenger car are implemented. Having joint robust stability and nominal performance of the closed loop is the main idea in this selection. In addition, it is very important to use these methods as a complementation for system physical insights, not supersedes. So, in the first place the system is described and the main ideas in ride comfort control are addressed. An 8 degrees of freedom model of vehicle with passive suspension system is derived and validated. Both linear and nonlinear models of the car which is equipped with hydro-active subsystem are derived. After selecting the outputs, for benefiting from minimum loop interactions, the control configuration is systematically determined. The main goal of selecting control configuration is assessing the possibility of achieving a decentralized control configuration. Finally, the system behavior is controlled by a decentralized proportional–integral–differential (PID) controller. The results indicate the efficiency of the controlled hydro-active suspension system in comparison with the passive system.
Generalized Cause-and-Effect Analyses for the Prototypic Nonlinear Mass–Spring–Damper System Using Volterra Kernels
Authors: Omran Ashraf , Newman Brett
Published: November 2012

This paper develops generalized analytical first and second Volterra kernels for the prototypic nonlinear mass–spring–damper system. The nonlinearity herein is mathematically considered in quadratic and bilinear terms. A variational expansion methodology, one of the most efficient analytical Volterra techniques, is used to develop an analytical two-term Volterra series. The resultant analytical first and second kernels are visualized in both the time and the frequency domains followed by a parametric study to understanding the influence of each nonlinear/linear term appearing in the kernel structure. An analytical nonlinear step and periodic responses are also conducted to characterize the overall system response from the fundamental components. The developed analytical responses provide an illumination for the source of differences between nonlinear and linear responses. Feasibility of the proposed implementation is assessed by numerical examples. The developed kernel-based model shows the ability to predict, understand, and analyze the system behavior beyond that attainable by the linear-based model.
Dynamic Optimization of Drivetrain Gear Ratio to Maximize Wind Turbine Power Generation—Part 1: System Model and Control Framework
Authors: Hall John F. , Chen Dongmei
Published: November 2012

Wind is considered to be one of the most promising resources in the renewable energy portfolio. Still, to make wind energy conversion more economically viable, it is necessary to extract greater power from the wind while minimizing the cost associated with the technology. This is particularly important for small wind turbines, which have the highest cost per kilowatt of energy produced. One solution would be a variable ratio gearbox (VRG) that can be integrated into the simple and low-cost fixed-speed induction generator. Through discrete variable rotor speed operation, the VRG-enabled system affects the wind speed ratio, the power coefficient, and ultimately the power produced. To maximize electrical production, mechanical braking is applied during the normal operation of the wind turbine. A strategy is used to select gear ratios (GRs) that produce torque slightly above the maximum amount the generator can accept while simultaneously applying the mechanical brake, so that full load production may be realized over greater ranges of the wind speed. To characterize the performance of the system, a 100 kW, fixed speed, stall-regulated wind turbine, has been developed for this study. The VRG-enabled wind turbine control system is presented in two papers. Part 1 focuses on the turbine simulation model, which includes the rotor, VRG-enabled drivetrain, disk brake, and electric generator. A technique for estimating the performance of a disk brake, in the wind turbine context, is also presented. Part 2 of the research will present a dynamic optimization algorithm that is used to establish the control protocol for competing performance objectives.
Comprehensive Nonlinear Modeling of a Pilot Operated Relief Valve
Authors: Gad Osama
Published: November 2012

This paper is directed toward a comprehensive nonlinear modeling and simulation of the performance of a class of a pilot operated relief valves. A mathematical model is deduced to predict the performance of the valve in the steady state and transient modes of operations. The developed model takes into consideration most nonlinearities of the valve and is studied within the MATLAB-SIMULINK environment. The validity of the proposed model is assessed experimentally in the steady state and transient modes of operations. The detailed modeling has resulted in a good agreement between simulation and experimental results. During the simulation studied, it was found that, nonlinearity occurs due to three factors: the pressure changes cause nonlinear velocity changes of the flow rate, the throttling area of the valve restriction usually changes nonlinearly, and the discharge coefficient of the throttling area of the valve restriction does not remain constant. In the transient mode of operation, the simulation studied identified some critical parameters which have a significant effect on the transient response of the valve. Most of the model’s parameters can be evaluated readily by direct measurement of the valve components dimensions thought the Coulomb friction factor and bulk modulus are tuned to match the model to the measurements.
A Hybrid Physical-Dynamic Tire/Road Friction Model
Authors: Li Jingliang , Zhang Yizhai , Yi Jingang
Published: November 2012

We present a hybrid physical-dynamic tire/road friction model for applications of vehicle motion simulation and control. We extend the LuGre dynamic friction model by considering the physical model-based adhesion/sliding partition of the tire/road contact patch. Comparison and model parameters relationship are presented between the physical and the LuGre dynamic friction models. We show that the LuGre dynamic friction model predicts the nonlinear and normal load-dependent rubber deformation and stress distributions on the contact patch. We also present the physical interpretation of the LuGre model parameters and their relationship with the physical model parameters. The analysis of the new hybrid model's properties resolves unrealistic nonzero bristle deformation and stress at the trailing edge of the contact patch that is predicted by the existing LuGre tire/road friction models. We further demonstrate the use of the hybrid model to simulate and study an aggressive pendulum-turn vehicle maneuver. The CARSIM simulation results by using the new hybrid friction model show high agreements with experiments that are performed by a professional racing car driver.
Parameter Estimation of an Electrohydraulic Servo System Using a Markov Chain Monte Carlo Method
Authors: Liu Junhong , Wu Huapeng , Handroos Heikki , Haario Heikki
Published: November 2012

A parameter estimation method is presented by an example of an electrohydraulic position servo. The method is based on the Markov chain Monte Carlo approach. The method allows utilization of noisy measurement data in identification process, making use of original physical data possible without the requirement of a filter. The method seeks for the best fitting point estimate of the unknown model parameter vector, but the solution to the parameter estimation problem is given as a statistical distribution that contains “all” the possible parameter combinations. The robustness of the model developed with the proposed method is further demonstrated by verification in operating conditions that are independent of each other and the one used in the identification step. Results show that the system model with the hybrid leakage formula for the studied valve describes the system dynamics more precisely and matches the real responses better.
Leading Edge Shielding Concept in Gas Turbines With Can Combustors
Authors: Aslanidou Ioanna , Rosic Budimir , Kanjirakkad Vasudevan , Uchida Sumiu
Published: November 2012

The remarkable developments in gas turbine materials and cooling technologies have allowed a steady increase in combustor outlet temperature and, hence, in gas turbine efficiency over the last half century. However, the efficiency benefits of higher gas temperature, even at the current levels, are significantly offset by the increased losses associated with the required cooling. Additionally, the advancements in gas turbine cooling technology have introduced considerable complexities into turbine design and manufacture. Therefore, a reduction in coolant requirements for the current gas temperature levels is one possible way for gas turbine designers to achieve even higher efficiency levels. The leading edges of the first turbine vane row are exposed to high heat loads. The high coolant requirements and geometry constraints limit the possible arrangement of the multiple rows of film cooling holes in the so-called showerhead region. In the past, investigators have tested many different showerhead configurations by varying the number of rows, inclination angle, and shape of the cooling holes. However, the current leading edge cooling strategies using showerheads have not been shown to allow a further increase in turbine temperature without the excessive use of coolant air. Therefore, new cooling strategies for the first vane have to be explored. In gas turbines with multiple combustor chambers around the annulus, the transition duct walls can be used to shield, i.e., to protect, the first vane leading edges from the high heat loads. In this way, the stagnation region at the leading edge and the showerhead of film cooling holes can be completely removed, resulting in a significant reduction in the total amount of cooling air that is otherwise required. By eliminating the showerhead the shielding concept significantly simplifies the design and lowers the manufacturing costs. This paper numerically analyzes the potential of the leading edge shielding concept for cooling air reduction. The vane shape was modified to allow for the implementation of the concept and nonrestrictive relative movement between the combustor and the vane. It has been demonstrated that the coolant flow that was originally used for cooling the combustor wall trailing edge and a fraction of the coolant air used for the vane showerhead cooling can be used to effectively cool both the suction and the pressure surfaces of the vane.
A Path Toward the Aerodynamic Robust Design of Low Pressure Turbines
Authors: Bertini Francesco , Credi Martina , Marconcini Michele , Giovannini Matteo
Published: November 2012

Airline companies are continuously demanding lower-fuel-consuming engines and this leads to investigating innovative configurations and to further improving single module performance. In this framework the low pressure turbine (LPT) is known to be a key component since it has a major effect on specific fuel consumption (SFC). Modern aerodynamic design of LPTs for civil aircraft engines has reached high levels of quality, but new engine data, after first engine tests, often cannot achieve the expected performance. Further work on the modules is usually required, with additional costs and time spent to reach the quality level needed to enter into service. The reported study is aimed at understanding some of the causes for this deficit and how to solve some of the highlighted problems. In a real engine, the LPT module works under conditions which differ from those described in the analyzed numerical model: the definition of the geometry cannot be so accurate, a priori unknown values for boundary conditions data are often assumed, complex physical phenomena are seldom taken into account, and operating cycle may differ from the design intent due to a nonoptimal coupling with other engine components. Moreover, variations are present among different engines of the same family, manufacturing defects increase the uncertainty and, finally, deterioration of the components occurs during service. Research projects and several studies carried out by the authors lead to the conclusion that being able to design a module whose performance is less sensitive to variations (robust LPT) brings advantages not only when the engine performs under strong off-design conditions but also, due to the abovementioned unknowns, near the design point as well. Concept and preliminary design phases are herein considered, highlighting the results arising from sensibility studies and their impact on the final designed robust configuration. Module performance is afterward estimated using a statistical approach.
Adaptive Cancellation of Matched Unknown Sinusoidal Disturbances for LTI Systems by State Derivative Feedback
Authors: Baştürk Halil İ. , Krstic Miroslav
Published: November 2012

Solutions already exist for the problem of canceling sinusoidal disturbances by measurement of state or an output for linear and nonlinear systems. In this paper, we design an adaptive controller to cancel matched sinusoidal disturbances forcing a linear time-invariant system by using only measurement of state-derivatives. Our design is based on three steps; (1) parametrization of the sinusoidal disturbance as the output of a known feedback system with an unknown output vector, (2) design of an adaptive disturbance observer and, (3) design of an adaptive controller. We prove that the equilibrium of the closed-loop adaptive system is globally uniformly asymptotically stable and locally exponentially stable. The effectiveness of the controller is illustrated with a simulation example of a second-order system.
Spatiotemporal Analysis of Cryptosporidium Species/Genotypes and Relationships with Other Zoonotic Pathogens in Surface Water from Mixed-Use Watersheds
Authors: Wilkes Graham , Ruecker Norma J. , Neumann Norman F. , Gannon Victor P. J. , Jokinen Cassandra , Sunohara Mark , Topp Edward , Pintar Katarina D. M. , Edge Thomas A. , Lapen David R.
Published: November 2012

Nearly 690 raw surface water samples were collected during a 6-year period from multiple watersheds in the South Nation River basin, Ontario, Canada.Cryptosporidiumoocysts in water samples were enumerated, sequenced, and genotyped by detailed phylogenetic analysis. The resulting species and genotypes were assigned to broad, known host and human infection risk classes. Wildlife/unknown, livestock, avian, and human host classes occurred in 21, 13, 3, and <1% of sampled surface waters, respectively.Cryptosporidium andersoniwas the most commonly detected livestock species, while muskrat I and II genotypes were the most dominant wildlife genotypes. The presence ofGiardiaspp.,Salmonellaspp.,Campylobacterspp., andEscherichia coliO157:H7 was evaluated in all water samples. The greatest significant odds ratios (odds of pathogen presence when host class is present/odds of pathogen presence when host class is absent) forGiardiaspp.,Campylobacterspp., andSalmonellaspp. in water were associated, respectively, with livestock (odds ratio of 3.1), avian (4.3), and livestock (9.3) host classes. Classification and regression tree analyses (CART) were used to group generalized host and human infection risk classes on the basis of a broad range of environmental and land use variables while tracking cooccurrence of zoonotic pathogens in these groupings. The occurrence of livestock-associatedCryptosporidiumwas most strongly related to agricultural water pollution in the fall (conditions also associated with elevated odds ratios of other zoonotic pathogens occurring in water in relation to all sampling conditions), whereas wildlife/unknown sources ofCryptosporidiumwere geospatially associated with smaller watercourses where urban/rural development was relatively lower. Conditions that support wildlife may not necessarily increase overall human infection risks associated withCryptosporidiumsince mostCryptosporidiumgenotypes classed as wildlife in this study (e.g., muskrat I and II genotype) do not pose significant infection risks to humans. Consequently, from a human health perspective, land use practices in agricultural watersheds that create opportunities for wildlife to flourish should not be rejected solely on the basis of their potential to increase relative proportions of wildlife fecal contamination in surface water. The present study suggests that mitigating livestock fecal pollution in surface water in this region would likely reduce human infection risks associated withCryptosporidiumand other zoonotic pathogens.
Intracellular Free Iron and Its Potential Role in Ultrahigh-Pressure-Induced Inactivation of Escherichia coli
Authors: Yan Yuan , Waite-Cusic Joy G. , Kuppusamy Periannan , Yousef Ahmed E.
Published: November 2012

Intracellular free iron of
Escherichia coli
was determined by whole-cell electron paramagnetic resonance spectrometry. Ultrahigh pressure (UHP) increased both intracellular free iron and cell lethality in a pressure-dose-dependent manner. The iron chelator 2,2′-dipyridyl protected cells against UHP treatments. A mutation that produced iron overload conditions sensitized
E. coli
to UHP treatment.
Chitin-Induced Gene Expression in Secondary Metabolic Pathways of Streptomyces coelicolor A3(2) Grown in Soil
Authors: Nazari Behnam , Kobayashi Michihiko , Saito Akihiro , Hassaninasab Azam , Miyashita Kiyotaka , Fujii Takeshi
Published: November 2012

Microarray analyses revealed that the expression of genes for secondary metabolism together with that of primary metabolic genes was induced by chitin in autoclaved soil cultures ofStreptomyces coelicolorA3(2). The data also indicated that DasR was involved in the regulation of gene expression for chitin catabolism, secondary metabolism, and stress responses.