bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of low-fat or full-fat fermented and non-fermented dairy foods on selected cardiovascular biomarkers in overweight adults
Authors: Nestel Paul J. , Mellett Natalie , Pally Suzana , Wong Gerard , Barlow Chris K. , Croft Kevin , Mori Trevor A. , Meikle Peter J.
Published: June 2013

The association between consumption of full-fat dairy foods and CVD may depend partly on the nature of products and may not apply to low-fat dairy foods. Increased circulating levels of inflammatory biomarkers after consumption of dairy product-rich meals suggest an association with CVD. In the present study, we tested the effects of low-fat and full-fat dairy diets on biomarkers associated with inflammation, oxidative stress or atherogenesis and on plasma lipid classes. Within full-fat dairy diets, we also compared fermented v. non-fermented products. In a randomised cross-over study, twelve overweight/obese subjects consumed during two 3-week periods two full-fat dairy diets containing either yogurt plus cheese (fermented) or butter, cream and ice cream (non-fermented) or a low-fat milk plus yogurt diet, with the latter being consumed between and at the end of the full-fat dairy dietary periods. The concentrations of six inflammatory and two atherogenic biomarkers known to be raised in CVD were measured as well as those of plasma F2-isoprostanes and lipid classes. The concentrations of six of the eight biomarkers tended to be higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet and the concentrations of two plasmalogen lipid classes reported to be associated with increased oxidisability were also higher on consumption of the low-fat dairy diet than on that of the fermented dairy diet (P< 0·001), although plasma F2-isoprostane concentrations did not differ on consumption of any of the diets. On the other hand, the concentrations of plasma sphingomyelin and IL-6 were significantly higher on consumption of the non-fermented dairy diet than on that of the low-fat dairy diet (P< 0·02). In conclusion, short-term diets containing low-fat dairy products did not lead to a more favourable biomarker profile associated with CVD risk compared with the full-fat dairy products, suggesting that full-fat fermented dairy products may be the more favourable.
Orientation-singularity analysis and orientationability evaluation of a special class of the Stewart–Gough parallel manipulators
Authors: Cao Yi , Gosselin Clément , Zhou Hui , Ren Ping , Ji Weixi
Published: June 2013

This paper addresses the orientation-singularity analysis and the orientationability evaluation of a special class of the Stewart–Gough parallel manipulators in which the moving and base platforms are two similar semi-symmetrical hexagons. Based on the half-angle transformation, an analytical polynomial of degree 13 that represents the orientation-singularity locus of this special class of parallel manipulators at a given position is derived. Graphical representations of the orientation-singularity locus of this class of manipulators are illustrated with examples to demonstrate the results. Based on the description of the orientation-singularity and nonsingular orientation region of this class of parallel manipulators, a performance index, referred to as orientationability, which describes the orientation capability of this class of manipulators at a given position, is introduced. A discretization algorithm is proposed for computing the orientationability of the special class of parallel manipulators at a given position in the workspace. Moreover, the effects of the design parameters and position parameters on the orientationability are also investigated in detail. Based on the orientationability performance index, another performance index, referred to as practical orientationability, representing the practical orientation capability of the manipulators at a given position, is introduced. In this performance index, singularities, the limitations of active and passive joints and link interferences are all taken into consideration. Furthermore, the practical orientationability of the special class of parallel manipulators studied here is also analyzed over several plane sections of the position-workspace in detail.
COST-EFFECTIVENESS OF ADHERENCE INTERVENTIONS FOR HIGHLY ACTIVE ANTIRETROVIRAL THERAPY: A SYSTEMATIC REVIEW
Authors: Mathes Tim , Pieper Dawid , Antoine Sunya-Lee , Eikermann Michaela
Published: June 2013

Objectives: The objective of this systematic review was to evaluate the cost-effectiveness of interventions aiming to increase the adherence to highly active antiretroviral therapy (HAART) in HIV-infected patients in developed countries (WHO stratum A).

Methods: A systematic search for comparative health economic studies was conducted in the following databases: EMBASE, MEDLINE, NHS Economic Evaluation Database, CINAHL, HEED, and EconLit. The identified publications were selected by two reviewers independently according to predefined inclusion and exclusion criteria. Furthermore, these were evaluated according to a standardized checklist and finally extracted, analyzed, and summarized.

Results: After reviewing the abstracts and full texts four relevant studies were identified. Different educational programs were compared as well as the Directly Observed Therapy (DOT). A critical aspect to be considered in particular was the poor transparency of the cost data. In three cost-utility analyses the costs per quality-adjusted life-year (QALY) in the baseline scenario were each under USD 15,000. The sensitivity analyses with a presumed maximum threshold of USD 50,000/QALY showed a predominantly cost-effective result. In one study that examined DOT the costs add up to over USD 150,000/QALY.

Conclusions: It seems that adherence interventions for HAART in HIV-infected patients can be cost-effective. Nevertheless, the quality of the included studies is deficient and only a few of the possible adherence interventions are taken into consideration. A final assessment of the cost-effectiveness of adherence interventions in general is, therefore, not possible.
Invariants of topological relative right equivalences
Authors: AHMED IMRAN , RUAS MARIA APARECIDA SOARES , TOMAZELLA JOÃO NIVALDO
Published: June 2013

Let (V,0) be the germ of an analytic variety in $\mathbb{C}^n$ and f an analytic function germ defined on V. For functions with isolated singularity on V, Bruce and Roberts introduced a generalization of the Milnor number of f, which we call Bruce–Roberts number, μBR(V,f). Like the Milnor number of f, this number shows some properties of f and V. In this paper we investigate algebraic and geometric characterizations of the constancy of the Bruce–Roberts number for families of functions with isolated singularities on V. We also discuss the topological invariance of the Bruce–Roberts number for families of quasihomogeneous functions defined on quasihomogeneous varieties. As application of the results, we prove a relative version of the Zariski multiplicity conjecture for quasihomogeneous varieties.
Iodine deficiency, thyroid function and hearing deficit: a review
Authors: Melse-Boonstra Alida , Mackenzie Ian
Published: June 2013

Iodine deficiency affects an estimated 241 million school-aged children in the world. Little is known about iodine deficiency in relation to auditory function, except for the fact that deaf–mutism is one of the features of cretinism. In the present review, we documented the scientific knowledge on the role of iodine and hypothyroidism in the auditory system. We found that ear development and hearing function depend on thyroid hormones. Multiple pathways are involved in this, including both inner ear morphology as well as neurological processes. Conductive as well as sensorineural hearing loss is found in studies with animals that were rendered hypothyroidic. In humans, auditory impairment is reported frequently in relation to hypothyroidism, ranging from mild disturbances to severe handicap. Auditory impairment has been related more explicitly to congenital hypothyroidism than to acquired hypothyroidism. The critical period for thyroid function-related hearing maturation is the first and second trimesters of pregnancy. Although only a limited number of studies have directly investigated the relationship between iodine deficiency and auditory function, most studies point toward an association. However, evidence from good randomised controlled trials is lacking. Inclusion of auditory outcomes in iodine supplementation studies is therefore to be recommended, especially for trials in pregnancy. Hearing deficit is an invisible abnormality, but has major consequences for educational and social skills if not detected. In view of this, auditory impairment should be mapped in iodine-deficient areas in order to realistically estimate the magnitude of the problem.
Critical water potentials for germination of wheat cultivars in the dryland Northwest USA
Authors: Singh Prabhakar , Ibrahim Hesham M. , Flury Markus , Schillinger William F. , Knappenberger Thorsten
Published: June 2013

Low soil water potential limits or prevents germination and emergence of rainfed winter wheat (Triticum aestivum L.). This phenomenon is particularly pronounced in the winter wheat–summer fallow region of the US Inland Pacific Northwest, where wheat is routinely sown deep to reach moisture with 12–15 cm of soil covering the seed. Wide differences in seedling emergence among winter wheat cultivars have been reported, but few previous experiments have examined germination differences among cultivars as a function of water potential. The objective of our laboratory study was to quantify seed germination of five commonly sown winter wheat cultivars (Moro, Xerpha, Eltan, Buchanan and Finley) at seven water potentials, ranging from 0 to − 1.5 MPa. Germination was measured as a function of time for a period of 30 d. At higher water potentials (0 to − 0.5 MPa), all cultivars had germination of more than 90%. At the lowest water potentials ( − 1.0 to − 1.25 MPa), however, Moro consistently exceeded the other cultivars for speed and extent of germination, with total germination of 74% at − 1.0 MPa and 43% at − 1.25 MPa. Since its release in 1966, Moro has been sown by farmers when seed-zone water conditions are marginal. Scientists have long known that coleoptile length is an important factor controlling winter wheat seedling emergence from deep sowing depths. In addition to having a long coleoptile, our data suggest that Moro's known excellent emergence ability from deep sowing depths in dry soils can also be attributed to the ability to germinate at lower water potentials than other cultivars.
Sodium butyrate improves the cloned yak embryo viability and corrects gene expression patterns
Authors: Xiong Xian-rong , Lan Dao-liang , Li Jian , Wang Yong , Zhong Jin-cheng
Published: June 2013

Interspecies somatic cell nuclear transfer (iSCNT), a powerful tool in basic scientific research, has been used widely to increase and preserve the population of endangered species. Yak (Bos grunniens) is one of these species. Development to term of interspecies cloned yak embryos has not been achieved, possibly due to abnormal epigenetic reprogramming. Previous studies have demonstrated that treatment of intraspecies cloned embryos with (NaBu) significantly improves nuclear–cytoplasmic reprogramming and viability in vitro. Therefore, in this study, we evaluated the effect of optimal NaBu concentration and exposure time on preimplantation development of yak iSCNT embryos and on the expression patterns of developmentally important genes. The results showed that 8-cell rate, blastocyst formation rate and total cell number increased significantly compared with their untreated counterparts when yak iSCNT embryos were treated with 5 nM NaBu for 12 h after activation, but that the 2-cell stage embryo rate was not significantly different. The treatment of NaBu also increased significantly the expression levels of Oct-4 and decreased the expression levels of HDAC-2, Dnmt-1 and IGF-1; the expression patterns of these genes were more similar to that of their bovine–yak in vitro fertilization (BY-IVF) counterparts. The results described above indicated that NaBu treatment improved developmental competence in vitro and ‘corrected’ the gene expression patterns of yak iSCNT embryos.
Quantitative analysis in LC3-II protein in vitro maturation of porcine oocyte
Authors: Lee SeungHoon , Hiradate Yuuki , Hoshino Yumi , Tanemura Kentaro , Sato Eimei
Published: June 2013

Microtubule-associated protein light chain 3 (LC3)-II is a marker of autophagosome. In this study, LC3-II expression was used to identify autophagy, during the in vitro maturation of porcine oocytes. In a time-course experiment, cumulus–oocyte complexes (COCs) were cultured in NCSU23 medium for 0 h, 14 h, 28 h or 42 h. The cumulus cells were removed and denuded oocytes were processed for western blotting or immunostaining. Western blotting showed that the LC3-II levels changed over time, with maximum levels observed at 14 h and minimum levels at 42 h. Immunostaining of LC3 showed the signals with dot shapes and ring shapes in oocytes at every group that probably represent autophagosomes. To ascertain whether autophagic induction and degradation were occurring, we treated the cultures with autophagic inhibitors. Lysosomal protease inhibitor E64d and pepstatin A increased the LC3-II levels and wortmannin, inhibitor of autophagic induction, decreased the LC3-II levels. Western blotting and immunostaining demonstrated that LC3-II is present in porcine oocytes cultured in vitro. The decreased LC3-II levels after wortmannin treatment suggest that it is newly generated in porcine oocytes, a phenomenon that represents autophagic induction. Furthermore, increased LC3-II levels after E64d and pepstatin A addition imply that LC3-II is degraded by lysosomal proteases, an indication of autophagic degradation. Our results suggest that autophagy, which is a dynamic process whereby autophagosomes are newly generated and subsequently degraded, is probably occurring in porcine oocytes during in vitro maturation.
Relationship between olfactory function and social cognition in euthymic bipolar patients
Authors: Lahera Guillermo , Ruiz-Murugarren Salvador , Fernández-Liria Alberto , Saiz-Ruiz Jerónimo , Buck Benjamin E. , Penn David L.
Published: June 2013

Objective/Introduction

There is a close functional and neuroanatomical relationship between olfactory ability and emotional processing. The present study seeks to explore the association between olfactory ability and social cognition, especially facial emotion perception, in euthymic bipolar patients.

Methods

Thirty-nine euthymic outpatients meeting DSM-IV-TR criteria for bipolar disorder and 40 healthy volunteers matched on socio-demographic criteria were recruited. Both groups were assessed at one time point with the University of Pennsylvania Smell Identification Test (UPSIT), the Emotion Recognition Test, and The Faux Pas Recognition Test, as well as measures of general cognition and functioning.

Results

The bipolar patients showed a significant impairment in olfactory identification (UPSIT) and social cognition measures compared to healthy controls. Analyses revealed significant relationships between olfactory identification and facial emotion recognition, theory of mind, general cognition, and a trend-level relationship with functioning. Controlling for age and cigarettes smoked, relationships remained significant between olfactory function and facial emotion recognition.

Conclusion

There is a deficit of olfactory identification in euthymic patients with bipolar disorder that is correlated with a deficit in both verbal and non-verbal measures of social cognition.
BANKS' PRECAUTIONARY CAPITAL AND CREDIT CRUNCHES
Authors: Valencia Fabián
Published: June 2013

This paper develops a bank model to study supply-driven contractions in credit or credit crunches. In the model, the bank is affected by financial frictions in raising external funds. These frictions imply that the bank repairs its balance sheet only gradually following a negative shock that weakens the bank's capital position. Consequently, there is persistency in the response of bank lending even when the original shock (productivity or interest rate) is i.i.d. The nonlinear nature of these financial frictions also generates (i) a precautionary motive even with risk-neutral shareholders: the bank increases its desired level of capital if risk increases; (ii) an asymmetric response of lending: negative disturbances can have a bigger impact than positive ones; and (iii) volatility clustering in risk spreads and the bank's share price.
Heart rate variability is a trait marker of major depressive disorder: evidence from the sertraline vs. electric current therapy to treat depression clinical study
Authors: Brunoni Andre Russowsky , Kemp Andrew H. , Dantas Eduardo M. , Goulart Alessandra C. , Nunes Maria Angélica , Boggio Paulo S. , Mill José Geraldo , Lotufo Paulo A. , Fregni Felipe , Benseñor Isabela M.
Published: June 2013

Decreased heart rate variability (HRV) is a cardiovascular predictor of mortality. Recent debate has focused on whether reductions in HRV in major depressive disorder (MDD) are a consequence of the disorder or a consequence of pharmacotherapy. Here we report on the impact of transcranial direct current stimulation (tDCS), a non-pharmacological intervention, vs. sertraline to further investigate this issue. The employed design was a double-blind, randomized, factorial, placebo-controlled trial. One hundred and eighteen moderate-to-severe, medication-free, low-cardiovascular risk depressed patients were recruited for this study and allocated to either active/sham tDCS (10 consecutive sessions plus two extra sessions every other week) or placebo/sertraline (50 mg/d) for 6 wk. Patients were age and gender-matched to healthy controls from a concurrent cohort study [the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)]. The impact of disorder, treatment and clinical response on HRV (root mean square of successive differences and high frequency) was examined. Our findings confirmed that patients displayed decreased HRV relative to controls. Furthermore, HRV scores did not change following treatment with either a non-pharmacological (tDCS) or pharmacological (sertraline) intervention, nor did HRV increase with clinical response to treatment. Based on these findings, we discuss whether reduced HRV is a trait-marker for MDD, which may predispose patients to a host of conditions and disease even after response to treatment. Our findings have important implications for our understanding of depression pathophysiology and the relationship between MDD, cardiovascular disorders and mortality.
The potential for detecting ‘life as we don't know it’ by fractal complexity analysis
Authors: Azua-Bustos Armando , Vega-Martínez Cristian
Published: June 2013

Finding life in the Universe entirely different to the one evolved on Earth is probable. This is a significant constraint for life-detecting instruments that were sent and may be sent elsewhere in the solar system, as how could we detect life as ‘we don't know it’? How could we detect something when we have no prior knowledge of its composition or how it looks like? Here we argue that disregarding the type of lifeform that could be envisioned, all must share in common the attribute of being entities that decrease their internal entropy at the expense of free energy obtained from its surroundings. As entropy quantifies the degree of disorder in a system, any envisioned lifeform must have a higher degree of order than its supporting environment. Here, we show that by using fractal mathematics analysis alone, one can readily quantify the degree of entropy difference (and thus, their structural complexity) of living processes (lichen growths and plant growing patterns in this case) as distinct entities separate from its similar abiotic surroundings. This approach may allow possible detection of unknown forms of life based on nothing more than entropy differentials of complementary datasets. Future explorations in the solar system, like Mars or Titan, may incorporate this concept in their mission planning in order to detect potential endemic lifeforms.
Perchlorate on Mars: a chemical hazard and a resource for humans
Authors: Davila Alfonso F. , Willson David , Coates John D. , McKay Christopher P.
Published: June 2013

Perchlorate (ClO4−) is widespread in Martian soils at concentrations between 0.5 and 1%. At such concentrations, perchlorate could be an important source of oxygen, but it could also become a critical chemical hazard to astronauts. In this paper, we review the dual implications of ClO4−on Mars, and propose a biochemical approach for removal of perchlorate from Martian soil that would be energetically cheap, environmentally friendly and could be used to obtain oxygen both for human consumption and to fuel surface operations.
Epigenetic changes in hypothalamic appetite regulatory genes may underlie the developmental programming for obesity in rat neonates subjected to a high-carbohydrate dietary modification
Authors: Mahmood S. , Smiraglia D. J. , Srinivasan M. , Patel M. S.
Published: June 2013

Earlier, we showed that rearing of newborn rats on a high-carbohydrate (HC) milk formula resulted in the onset of hyperinsulinemia, its persistence in the post-weaning period and adult-onset obesity. DNA methylation of CpG dinucleotides in the proximal promoter region and modifications in the N-terminal tail of histone 3 associated with the neuropeptide Y (Npy) and pro-opiomelanocortin (Pomc) genes were investigated to decipher the molecular mechanisms supporting the development of obesity in HC females. Although there were no differences in the methylation status of CpG dinucleotides in the proximal promoter region of the Pomc gene, altered methylation of specific CpG dinucleotides proximal to the transcription start site was observed for the Npy gene in the hypothalami of 16- and 100-day-old HC rats compared with their methylation status in mother-fed (MF) rats. Investigation of histone tail modifications on hypothalamic chromatin extracts from 16-day-old rats indicated decreased acetylation of lysine 9 in histone 3 (H3K9) for the Pomc gene and increased acetylation for the same residue for the Npy gene, without changes in histone methylation (H3K9) in both genes in HC rats. These findings are consistent with the changes in the levels of Npy and Pomc mRNAs in the hypothalami of HC rats compared with MF animals. Our results suggest that epigenetic modifications could contribute to the altered gene expression of the Npy and Pomc genes in the hypothalami of HC rats and could be a mechanism leading to hyperphagia and the development of obesity in adult female HC rats.
Zur Wirksamkeit des JobFit-Trainings – ein Vergleich zwischen Jugendlichen mit und ohne Migrationshintergrund
Authors: Laakmann Mirjam , Schultheiß Jan , Petermann Franz , Petermann Ulrike
Published: June 2013

Die Studie (n = 273) vergleicht die Wirksamkeit des JobFit-Trainings bei Jugendlichen mit und ohne Migrationshintergrund. 130 Schüler haben einen Migrationshintergrund und 143 Schüler sind deutschstämmig. Alle Schüler verbessern sich in ihren sozialen Kompetenzen, die mit der Schülereinschätzliste für Sozial- und Lernverhalten (SSL) erhoben wurden. Vor Beginn des Trainings unterschieden sich die Jugendlichen mit und ohne Migrationshintergrund hinsichtlich ihrer sozialen Kompetenzen und des Lernverhaltens; die Jugendlichen mit Migrationshintergrund zeigten generell bessere Werte. Jugendliche mit Migrationshintergrund können durch das Training ihre sozialen Kompetenzen deutlicher steigern als Jugendliche ohne Migrationshintergrund. Mögliche Erklärungen für die Ergebnisse im Hinblick auf die Selbstwahrnehmung der Jugendlichen werden diskutiert.
Soluble TNF Receptor 1-Secreting ex Vivo-Derived Dendritic Cells Reduce Injury After Stroke
Authors: Works Melissa G , Koenig Jenny B , Sapolsky Robert M
Published: June 2013

Inflammation is a major factor in the progression of damage after stroke and in the clinic, current therapies treat the clot, not the resulting damage. We have developed a novel method of protein delivery that exploits the migration ability of leukocytes after ischemic stroke (transient middle cerebral artery occlusion; tMCAO). In our studies, ex vivo-derived dendritic cells (exDCs) migrate to the inflamed rat brain soon after tMCAO onset and the number of cells that remain in the brain after injection is significantly correlated with the amount of local inflammation at the injury site. In addition, exDCs transduced to overexpress soluble tumor necrosis factor (TNF) receptor1 (sTNFR1) produce functional cargo that is secreted and that blocks TNF-α bioavailability in vitro. When delivered at 6 hours post-tMCAO reperfusion, sTNFR1-exDC-treated rats show significantly smaller infarct size and decreased inflammation compared with animals treated with exDCs transduced with GFP lentivirus. These studies indicate that cell-mediated delivery of proteins may be a promising new approach to reduce brain damage after acute neurologic insult.
Kinetic Analysis of Glycogen Turnover: Relevance to Human Brain 13C-NMR Spectroscopy
Authors: DiNuzzo Mauro
Published: June 2013

A biophysical model of the glycogen molecule is developed, which takes into account the points of attack of synthase and phosphorylase at the level of the individual glucose chain. Under the sole assumption of steric effects governing enzyme accessibility to glucosyl residues, the model reproduces the known equilibrium structure of cellular glycogen at steady state. In particular, experimental data are reproduced assuming that synthase (1) operates preferentially on inner chains of the molecule and (2) exhibits a faster mobility than phosphorylase in translocating from an attacked chain to another. The model is then used to examine the turnover of outer versus inner tiers during the labeling process of isotopic enrichment (IE) experiments. Simulated data are fitted to in vivo13C nuclear magnetic resonance spectroscopy measurements obtained in the human brain under resting conditions. Within this experimental set-up, analysis of simulated label incorporation and retention shows that 7% to 35% of labeled glucose is lost from the rapidly turning-over surface of the glycogen molecule when stimulation onset is delayed by 7 to 11.5 hours after the end of [1-13C]glucose infusion as done in actual procedures. The substantial label washout before stimulation suggests that much of the subsequent activation-induced glycogenolysis could remain undetected. Overall, these results show that the molecular structure significantly affects the patterns of synthesis and degradation of glycogen, which is relevant for appropriate design of labeling experiments aiming at investigating the functional roles of this glucose reserve.
Comparative cross-linking and mass spectrometry of an intact F-type ATPase suggest a role for phosphorylation
Authors: Schmidt Carla , Zhou Min , Marriott Hazel , Morgner Nina , Politis Argyris , Robinson Carol V.
Published: June 2013

F-type ATPases are highly conserved enzymes used primarily for the synthesis of ATP. Here we apply mass spectrometry to the F1FO-ATPase, isolated from spinach chloroplasts, and uncover multiple modifications in soluble and membrane subunits. Mass spectra of the intact ATPase define a stable lipid ‘plug’ in the FO complex and reveal the stoichiometry of nucleotide binding in the F1 head. Comparing complexes formed in solution from an untreated ATPase with one incubated with a phosphatase reveals that the dephosphorylated enzyme has reduced nucleotide occupancy and decreased stability. By contrasting chemical cross-linking of untreated and dephosphorylated forms we show that cross-links are retained between the head and base, but are significantly reduced in the head, stators and stalk. Conformational changes at the catalytic interface, evidenced by changes in cross-linking, provide a rationale for reduced nucleotide occupancy and highlight a role for phosphorylation in regulating nucleotide binding and stability of the chloroplast ATPase.
CD25 and CD69 induction by α4β1 outside-in signalling requires TCR early signalling complex proteins
Authors: Cimo Ann-Marie , Ahmed Zamal , McIntyre Bradley W. , Lewis Dorothy E. , Ladbury John E.
Published: June 2013

Distinct signalling pathways producing diverse cellular outcomes can utilize similar subsets of proteins. For example, proteins from the TCR (T-cell receptor) ESC (early signalling complex) are also involved in interferon-α receptor signalling. Defining the mechanism for how these proteins function within a given pathway is important in understanding the integration and communication of signalling networks with one another. We investigated the contributions of the TCR ESC proteins Lck (lymphocyte-specific kinase), ZAP-70 (ζ-chain-associated protein of 70 kDa), Vav1, SLP-76 [SH2 (Src homology 2)-domain-containing leukocyte protein of 76 kDa] and LAT (linker for activation of T-cells) to integrin outside-in signalling in human T-cells. Lck, ZAP-70, SLP-76, Vav1 and LAT were activated by α4β1 outside-in signalling, but in a manner different from TCR signalling. TCR stimulation recruits ESC proteins to activate the mitogen-activated protein kinase ERK (extracellular-signal-regulated kinase). α4β1 outside-in-mediated ERK activation did not require TCR ESC proteins. However, α4β1 outside-in signalling induced CD25 and co-stimulated CD69 and this was dependent on TCR ESC proteins. TCR and α4β1 outside-in signalling are integrated through the common use of TCR ESC proteins; however, these proteins display functionally distinct roles in these pathways. These novel insights into the cross-talk between integrin outside-in and TCR signalling pathways are highly relevant to the development of therapeutic strategies to overcome disease associated with T-cell deregulation.
Multi‐stage control strategy for quantised feedback control systems
Authors: Kim Sung Hyun
Published: June 2013

This study establishes a multi‐stage control strategy that can systematically reduce the effect of quantisation errors without resort to any prescribed control gains applicable to the stabilisation of quantisation‐free systems. First of all, a two‐stage control strategy is built under a fixed quantisation sensitivity, and then a multi‐stage control strategy is established on the possibility of adjusting on‐line the quantisation sensitivity. In the derivation, the overall control law is constructed with linear and non‐linear feedback controls, where non‐linear feedback control plays an important role of eliminating the effect of control input quantisation errors.
H∞ state‐feedback control of bilateral teleoperation systems with asymmetric time‐varying delays
Authors: Du Haiping
Published: June 2013

In this study, a novel controller synthesis method is proposed for the bilateral teleoperation systems with asymmetric time‐varying delays. The main idea of the proposed method is to deal with the control problem for a bilateral teleoperation system under asymmetric time‐varying delays as a control problem for a system with multiple input time delays, and then to find the state‐feedback control law to stabilise the system with guaranteed H∞ performance on the defined control output. With intentionally introducing the pretend time delays to the (local) state variables of the master or the slave, the teleoperation controller design problem is converted to a controller synthesis problem for a system with multiple input time delays. Then the state‐feedback controllers are designed for both the master and the slave by defining an appropriate Lyapunov–Krasovskii functional candidate and solving linear matrix inequalities. The designed controllers guarantee the closed‐loop system stability and system transparency performance in terms of the optimised H∞ norm on the position and force tracking errors between the master and the slave. At last numerical simulations are used to validate the effectiveness of the proposed method. The results show that the designed controllers can effectively stabilise the present teleoperation system with good transparency performance under time‐varying delays.
Non‐linear generalised minimum variance control using unstable state‐dependent multivariable models
Authors: Grimble Mike John , Majecki Pawel
Published: June 2013

A non‐linear generalised minimum variance (NGMV) control law is derived for systems represented by an input–output state dependent non‐linear (NL) subsystem that may be open‐loop unstable. The solution is obtained using a model for the multivariable discrete‐time process that includes a state‐dependent (NL and possibly unstable) model that links the output and any ‘unstructured’ NL input subsystem. The input subsystem can involve an operator of a very general NL form, but this has to be assumed to be stable. This is the first NGMV control solution that is suitable for systems containing an unstable NL sub‐system which is contained in the state‐dependent model. The process is also assumed to include explicit common delays in input or output channels. The generalised minimum variance cost index to be minimised involves both dynamically weighted error and control signal costing terms. It may also include weighted values of the system states for greater generality. The controller derived is simple to implement considering the complexity of the system represented. If the plant is stable the controller structure can be manipulated into an internal model control form. This form of the controller is like an NL version of the Smith Predictor which is valuable for providing confidence in the solution.
Domain of attraction and guaranteed cost control for non‐linear quadratic systems. Part 2: controller design
Authors: Amato Francesco , Ambrosino Roberto , Ariola Marco , Merola Alessio
Published: June 2013

This study addresses the problem of designing a guaranteed cost controller for non‐linear discrete quadratic systems. More specifically, the main contribution concerns a sufficient condition for the existence of a state‐feedback controller achieving a certain guaranteed cost, whenever the state trajectories start from a prescribed set of initial conditions. The controller design requires the solution of a convex optimisation problem involving linear matrix inequalities, which can be efficiently solved via available optimisation algorithms. Finally, the proposed design methodology is illustrated via an example concerning the attitude control of an unmanned aerial vehicle.
Bounded real lemma for positive discrete systems
Authors: Wang Cuihong
Published: June 2013

The bounded real lemma for positive discrete time‐invariant systems is addressed in this study. The results about bounded real lemma for continuous time‐invariant systems are extended into discrete time‐invariant systems. Such systems are asymptotically stable and their H∞ norm less than one is equivalent to that the corresponding linear matrix inequality admits a diagonal positive‐definite solution. The last example in this study illustrates the result does not hold for general discrete time‐invariant systems.
Formation tracking control for a class of multiple mobile robots in the presence of unknown skidding and slipping
Authors: Yoo Sung Jin , Park Bong Seok
Published: June 2013

This study investigates the formation control problem for a class of multiple mobile robots considering unknown skidding and slipping, and torque saturation. The kinematics and dynamics of multiple mobile robots with skidding and slipping effects are considered. The proposed formation control scheme is derived from the dynamic surface design and virtual structure approach where the reference trajectories consisting of path parameters are employed to satisfy both the tracking control and the formation maintenance. The adaptive technique is used to compensate the unknown skidding and slipping effects. From Lyapunov‐stability analysis, we prove regardless of unknown skidding and slipping that all signals of the total closed‐loop system are semiglobally uniformly ultimately bounded and the point‐tracking errors and the synchronisation error for the desired formation converge to an adjustable neighbourhood of the origin. In addition, it is analysed that the orientation error for each robot is related to the speed of the reference trajectory and the skidding effect. The performance and stability of the proposed approach are verified from simulation results.
ℋ∞ control for asynchronously switched linear parameter‐varying systems with mode‐dependent average dwell time
Authors: Lu Qiugang , Zhang Lixian , Karimi Hamid Reza , Shi Yang
Published: June 2013

This study is concerned with the stability, l2 ‐gain analysis and ℋ∞ control for a class of discrete‐time switched linear parameter‐varying systems with both mode‐dependent average dwell time (MDADT) and asynchronous switching, where ‘asynchronous’ means the switching of controllers has a lag to the switching of system modes. The l2 ‐gain for general switched systems with MDADT in non‐linear setting is firstly derived. Based on the obtained results, the problem of asynchronous ℋ∞ control for the studied systems is formulated under the framework of MDADT switching logic, and the conditions for the existence of admissible asynchronous ℋ∞ controllers are deduced in the form of parameterised linear matrix inequalities. A numerical example is provided to verify the effectiveness of the acquired results.
Robust predictive tracking control of networked control systems with time‐varying delays and data dropouts
Authors: Liu Yuan‐Ming , Fong I‐Kong
Published: June 2013

This study deals with a robust trajectory tracking control problem of discrete‐time networked control systems. The systems have time‐varying interval‐bounded uncertainties, random network‐induced delays and data dropouts in both sensor‐to‐controller channel and controller‐to‐buffer/actuator channel. A dynamic predictive feedback linearisation controller is proposed so that the system dynamics and delays caused by networked communication time and data dropouts are compensated, and the system output can perfectly track the reference trajectory when uncertainties are absent. Tracking errors caused by the time‐varying parameter uncertainties are suppressed in the H∞ sense. Finally, the proposed method is illustrated by two numerical examples which show the application procedure and effectiveness of the proposed control scheme.
On stability of non‐linear and switched parabolic systems
Authors: Yang Hao , Jiang Bin
Published: June 2013

This study investigates the stability of non‐linear parabolic systems. Several stability conditions based on separable Lyapunov functions are provided. The new results are applied to switched non‐linear parabolic systems with all stable modes or with unstable modes. An example of heat propagation control of semiconductor power chips is taken to illustrate the proposed methods.
Universal Kriging control of hypersonic aircraft model using predictor model without back‐stepping
Authors: Xu Bin , Shi Zhongke
Published: June 2013

This study describes the design of adaptive universal Kriging (UK) controller for the longitudinal dynamics of a generic hypersonic flight vehicle (HFV). The altitude subsystem is transformed into the explicit four‐step ahead state predictor model, which provides the relationship between states and future outputs. Furthermore, the input‐‐output predictor model is derived to obtain the input information for the UK estimator. The UK takes advantages of the parametric regression model and simple Kriging model to describe the systematic aspects and local fluctuations of unknown functions simultaneously. With the state prediction feedback and input‐‐output UK estimation, the controller is synthesised. The control scheme is considerably simpler than the ones based on back‐stepping since only one Kriging system is employed to approximate the lumped system uncertainty. Owing to the prediction function and the UK structure, the novel stochastic Lyapunov function‐based stability analysis is conducted. The closed‐loop system achieves almost surely boundedness. The effectiveness of the proposed control approach is verified by step tracking.
Methodology for the selection of long‐medium‐voltage power cable configurations
Authors: Kaloudas Christos G. , Papadopoulos Theofilos A. , Gouramanis Kostas V. , Stasinos Konstantinos , Papagiannis Grigoris K.
Published: June 2013

Single conductor cables are widely used in several types of installations over the last years, including the interconnection of wind parks to the power grid. Owing to the complexity of cable installations each configuration must be treated individually, regarding the use of sheath cross‐bonding, the influence of grounding resistances and the use of sheath voltage limiters. In this study, a systematic investigation of the performance of a long‐medium‐voltage cable configuration is presented. Sheath voltages and currents are calculated during steady‐state and short‐circuit conditions for varying sheath arrangements using the ATP/EMTP software. Results are validated by field measurements. The analysis is also extended to include the investigation of overvoltages in the installation, during slow and fast transients, according to the basic insulation level for the cable system.
Application of sparse‐grid technique to chance constrained optimal power flow
Authors: Zhang Hui , Li Pu
Published: June 2013

The method of chance constrained optimisation (CCOPT) provides a suitable way to address operations planning of power transmission networks under uncertainty. However, since many uncertain variables as well as many output constraints have to be considered in optimal power flow (OPF), the computational demand to solve the CCOPT problem will be prohibitive. In this study, the authors employ the sparse‐grid technique for computing the values and gradients of the objective function and probability constraints, with which the computation efficiency can be significantly enhanced. The authors consider optimal operations planning under uncertain demands at different nodes of networks. Based on the non‐linear OPF model, the results of solving the CCOPT problem for the IEEE 57‐bus and 118‐bus systems demonstrate the efficiency of the proposed approach.
On‐line assessment of the transient instability risk
Authors: Abapour Mehdi , Haghifam Mahmoud‐Reza
Published: June 2013

This study provides an algorithm for the rapid on‐line transient instability risk assessment associated with existing or forecasted operation conditions. The increasing need to balance the system stability level with its operation costs is the main motivation of the present study. The transient instability risk is defined in terms of the probability of transient instability and its cost. The proposed algorithm is an analytical on‐line method making use of three types of information: (i) a transient stability assessment tool, (ii) probabilistic factors of conditional probability theorem and (iii) the cost of transient instability. The risk calculated through the proposed method returns the probabilistic cost of transient instability, and can be used by system operators to improve transient stability with cost‐effective changes in the output power of generators. The IEEE New‐England 39 bus test system was used to demonstrate the feasibility and applicability of the presented method.
Approach to trace and locate long‐term voltage instability risk in power system planning
Authors: Yu Juan , Li Wenyuan , Ajjarapu Venkataramana , Yan Wei , Zhao Xia
Published: June 2013

With the integration of a quadratic optimisation method into one single Monte Carlo simulation, the system‐wide and local risk index functions are developed to quantify the relations between the system‐wide and local voltage stability risk and load levels. Each defined risk index function is a function of load level under various possible pre‐contingency and contingency states and load uncertainty. Based on the proposed risk index functions, a method of tracing and locating long‐term voltage instability risk in power system planning is presented. The methodology can trace the overall system‐wide voltage instability risk in a planning timeframe and locate weak branches and buses. The effectiveness of the proposed method is demonstrated using the IEEE 14‐bus system and an actual utility system with 171 buses.
Subsynchronous resonance mitigation using variable‐speed wind energy conversion systems
Authors: Leon Andres Enrique , Mauricio Juan Manuel , Solsona Jorge Alberto
Published: June 2013

This work proposes a strategy to mitigate subsynchronous resonance (SSR) in synchronous generators using variable‐speed wind energy conversion systems (WECSs) based on full converter wind turbines. A supplementary active and reactive power to be delivered by WECSs located near synchronous generators is designed to reduce the SSR phenomenon. These supplementary signals are calculated using an observer‐based controller tuned through an optimal quadratic technique which allows to minimise the WECS control effort, whereas a good torsional oscillation damping is accomplished. The power ratio between the WECS and the synchronous generator, impact on the power quality and communication time‐delay requirements are also discussed. The authors compare two control approaches: the first one uses mechanical measurements of the synchronous generator (measures which have high observability of torsional modes), whereas the second one uses voltage measurements at the wind farm connection point. In this way, two control schemes using remote and local measurements are proposed, and advantages and disadvantages of both schemes are presented. The proposed scheme can provide satisfactory torsional damping under a wide range of operating points, avoiding to include dedicated SSR damping equipment, and using the new wind farms installed in the network. Eigenvalue analysis and non‐linear time‐domain simulations confirm the good performance of the WECS‐based SSR damping controller.
State estimation in power systems using linear model infinity norm‐based trust region approach
Authors: Sravan Kumar V. Seshadri , Dhadbanjan Thukaram
Published: June 2013

State estimation is one of the most important functions in an energy control centre. An computationally efficient state estimator which is free from numerical instability/ill‐conditioning is essential for security assessment of electric power grid. Whereas approaches to successfully overcome the numerical ill‐conditioning issues have been proposed, an efficient algorithm for addressing the convergence issues in the presence of topological errors is yet to be evolved. Trust region (TR) methods have been successfully employed to overcome the divergence problem to certain extent. In this study, case studies are presented where the conventional algorithms including the existing TR methods would fail to converge. A linearised model‐based TR method for successfully overcoming the convergence issues is proposed. On the computational front, unlike the existing TR methods for state estimation which employ quadratic models, the proposed linear model‐based estimator is computationally efficient because the model minimiser can be computed in a single step. The model minimiser at each step is computed by minimising the linearised model in the presence of TR and measurement mismatch constraints. The infinity norm is used to define the geometry of the TR. Measurement mismatch constraints are employed to improve the accuracy. The proposed algorithm is compared with the quadratic model‐based TR algorithm with case studies on the IEEE 30‐bus system, 205‐bus and 514‐bus equivalent systems of part of Indian grid.