bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological Intervention: Prospects and Limits
Authors: Eckersley Robyn
Published: September 2007

This essay seeks to extend the already controversial debate about humanitarian intervention by exploring the morality, legality, and legitimacy of ecological intervention and its corollary, ecological defense. If the legacy of the Holocaust was acceptance of a new category of “crimes against humanity” and an emerging norm of humanitarian intervention, then should the willful or reckless perpetration of mass extinctions and massive ecosystem destruction be regarded as “crimes against nature” or “ecocide” such as to ground a new norm of ecological intervention or ecological defense? The essay shows that the minimalist argument for ecological intervention—multilateral intervention in the case of environmental emergencies with major transboundary spillover effects—is the strongest and may be defended as ecological self-defense. “Eco-humanitarian intervention” to prevent ecocide involving serious human rights violations has the same precarious status as humanitarian intervention, however, and is unlikely to garner the support of developing countries. The most challenging case of all—the military rescue of nonhuman species—finds moral support in environmental philosophy but conflicts with deeply entrenched international legal and political norms concerning state territorial rights.
Poverty and Global Justice
Authors: Kokaz Nancy
Published: September 2007

Poverty eradication has been identified as the largest challenge facing international society in its quest for a peaceful, prosperous, and just world. I respond to this challenge by proposing a global poverty eradication principle. Grounded in John Rawls's account of human rights and assistance for the law of peoples, the global poverty eradication principle applies regardless of causal patterns that may obtain in a given case. The relationship between persons affected by poverty and their governments has implications only for the selection of the appropriate means of poverty eradication, but never undermines the goal of poverty eradication itself. The duties of human rights and assistance that establish the global poverty eradication principle apply even to societies that may reject them, because they are institutional reaffirmations of the natural duties of persons in the context of international society, without whose affirmation no domestic society can be considered well-ordered. I conclude by pointing out some of the challenges that are likely to arise in the application of the global poverty eradication principle. While I cannot hope to settle these practical problems philosophically, flagging them helps to clarify the scope of application of the global poverty eradication principle and gives a sense of the concrete targets and measures that could be adopted in working toward its fulfillment in practice, especially for the elimination of certain types of severe deprivation at a minimum.
Reconstructing Precaution, Deconstructing Misconceptions
Authors: Arcuri Alessandra
Published: September 2007

The precautionary principle, widely endorsed at the national and international level, continues to be at the center of a heated debate. Some authors claim that the principle is unscientific; others argue that the principle is paralyzing and gives decision-makers no direction. Confusion and misconceptions are generated by the multiplicity of definitions and interpretations of the precautionary principle. This essay contributes to the debate on the precautionary principle in two ways: (1) it clarifies what a mild formulation of the principle entails, and (2) it identifies a number of misconceptions underlying some of the main criticisms of the principle.

A reasonable formulation of the precautionary principle requires both substantive and procedural elements: the substantive element suggests that in circumstances where uncertainties and risks of irreversible harms are present, decisions should err on the side of environmental preservation; the procedural element suggests that the principle should favour decision-making processes that are iterative and informative over time and that integrate experts' assessments of the risks to be governed and people's preferences and values.

Against this background, five misconceptions underlying the main criticisms of the precautionary principle are identified and deconstructed. The analysis of the misconceptions sheds further light on the fact that following the principle, processes of learning are stimulated, and accordingly, technology is not halted; to the contrary, the application of the principle leads to a better understanding of technological developments and their effects.
Thermal Characterization In Vitro of Human Nail: Photoacoustic Study of the Aging Process
Authors: Dias Daniele Toniolo , Steimacher Alysson , Bento Antonio Carlos , Neto Antonio Medina , Baesso Mauro Luciano
Published: September 2007

In the present work, the rear photoacoustic signal technique is used to determine thermal properties of human nails. The aging process of the human nail is analyzed through its thermal diffusivity and specific heat and using these results, thermal conductivity and thermal effusivity is determined. The study in vitro of this natural polymer showed a minimum for thermal properties to age about 20 years and an increase and possible saturation of them for ages over 50 years. The minimum value found for thermal diffusivity was close to 10 × 10−4 cm2 s−1 with saturation near 18 × 10−4 cm2 s−1. Thermal conductivity and effusivity presents the same behavior.
Apoptosis and Autophagy After Mitochondrial or Endoplasmic Reticulum Photodamage†
Authors: Kessel David , Reiners John J.
Published: September 2007

Photodynamic therapy (PDT) can cause lethal photodamage by both direct and indirect mechanisms. Direct modes of cell death relate to nonspecific necrosis and the initiation of signaling pathways that elicit apoptosis, autophagy or both. In this report, effects of low‐dose and high‐dose PDT are explored, comparing sensitizers that localize in the endoplasmic reticulum (the porphycene termed CPO) or mitochondria (mesochlorin). To explore the role of autophagy, two cell lines were examined—the murine L1210 leukemia and an Atg7 knockdown derivative of L1210. The Atg7 gene is central to the process of autophagy. High‐dose PDT with either sensitizer resulted in a substantial loss of the Bcl‐2 protein. As Bcl‐2 regulates both apoptosis and autophagy, loss of this protein can lead to initiation of either or both processes. Low‐dose PDT with either sensitizer resulted in the initiation of apoptosis in the L1210/Atg7− cell line and a 20% loss of viability. In contrast, the same PDT dose led to the rapid appearance of autophagic cells in the L1210 line, less apoptosis and only a 5% loss of viability. These results are consistent with autophagy serving as a pro‐survival response via the recycling of damaged organelles. At a higher PDT dose more apoptosis was again seen in the L1210/Atg7‐ line, but both cell lines exhibited comparable cytotoxicity in colony formation assays. We conclude that autophagy offers protection from the phototoxic effects of low‐dose PDT, but can serve as an alternate death mode when the PDT dose is increased.
Mono‐(l)‐aspartylchlorin‐e6†‡
Authors: Hargus Jodie A. , Fronczek Frank R. , Vicente M. Graça H. , Smith Kevin M.
Published: September 2007

Mono‐(l)‐aspartylchlorin‐e6 (also known as Talaporfin, NPe6, MACE, and most recently LS‐11) is a potent sensitizer for photodynamic therapy that is currently undergoing clinical trials. Using a combination of unambiguous partial synthesis from pheophytin‐a and methyl pheophorbide‐a, NMR spectroscopy, and single crystal X‐ray diffraction, the structure of mono‐(l)‐aspartylchlorin‐e6 is definitively shown to be the isomer in which the aspartyl residue is attached at the 152‐side chain position. This conclusion is contrary to earlier assumptions, but affirms the conclusions of a study based on NMR spectroscopy; a rationale for the unique formation of the 152‐aspartyl derivative is proposed.
Modulation of Hypericin Photodynamic Therapy by Pretreatment with 12 Various Inhibitors of Arachidonic Acid Metabolism in Colon Adenocarcinoma HT‐29 Cells
Authors: Kleban Ján , Mikeš Jaromír , Szilárdiová Beáta , Kovaľ Ján , Sačková Veronika , Solár Peter , Horváth Viktor , Hofmanová Jiřina , Kozubík Alois , Fedoročko Peter
Published: September 2007

One proposal to increase the efficiency of photodynamic therapy (PDT) is to accompany photosensitization with other treatment modalities, including modulation of arachidonic acid (AA) metabolism. The aim of this study was to evaluate the effectiveness of a combined modality approach employing 48 and 24 h pretreatment with various inhibitors of lipoxygenase (LOX; nordihydroguaiaretic acid, esculetin, AA‐861, MK‐886 and baicalein), cyclooxygenase (COX; diclofenac, flurbiprofen, ibuprofen, indomethacin, SC‐560 and rofecoxib) and cytochrome P450‐monooxygenase (proadifen) pathways, followed by hypericin‐mediated PDT. Cytokinetic parameters like MTT assay, adherent and floating cell numbers, viability and cell cycle distribution analysis were examined 24 h after hypericin activation. Pretreatment of human colon cancer cells HT‐29 prior to PDT with 5‐LOX inhibitor MK‐886 as well as 5, 12‐LOX and 12‐LOX inhibitors (esculetin and baicalein, respectively) resulted in significant and dose‐dependent effects on all parameters tested. Pretreatment with diclofenac, flurbiprofen, ibuprofen and indomethacin, the nonspecific COX inhibitors, promoted hypericin‐mediated PDT, but these effects were probably COX‐independent. In contrast, application of SC‐560 and rofecoxib, specific inhibitors of COX‐1 and COX‐2, respectively, attenuated PDT. Inhibition of P450 monooxygenase with proadifen implied also the significance of this metabolic pathway in cell survival and cell resistance to hypericin photocytotoxicity. In conclusion, our results testify that application of diverse inhibitors of AA metabolism may have different consequences on cellular response to hypericin‐mediated PDT and that some of them could be considered for potentiation of PDT.
Irradiation‐Induced Enhancement of Pc 4 Fluorescence and Changes in Light Scattering are Potential Dosimeters for Pc 4‐PDT†
Authors: Wang Ken Kang‐Hsin , Wilson Jeremy D. , Kenney Malcolm E. , Mitra Soumya , Foster Thomas H.
Published: September 2007

Phthalocyanine 4 (Pc 4) is a promising photosensitizer currently in clinical trials. Photobiological responses to Pc 4 photodynamic therapy (Pc 4‐PDT) have been characterized extensively, but relatively little has been done to evaluate dose metrics for this sensitizer. We describe an irradiation‐induced increase in fluorescence in tumor cell monolayers. This increase is due solely to enhanced fluorescence from Pc 4, as confirmed by confocal spectroscopy. In EMT6 cells incubated with 250 nM Pc 4 for 24 h, the maximum increase in fluorescence is approximately 3.7‐fold above baseline levels. This increase occurs over a range of fluences, 0.05 – 0.6 J cm−2, where clonogenic survival decreases by 3 orders of magnitude. Light scattering measurements performed on similarly treated EMT6 cells in suspension suggested a Pc 4‐PDT‐mediated mitochondrial swelling of approximately 13% at 0.6 J cm−2, where fluorescence enhancement saturates under these treatment conditions. Fluorescence imaging and light scattering experiments performed at a five‐fold lower Pc 4 incubation concentration revealed a reduced fluorescence enhancement at a five‐fold higher fluence, which produced comparable mitochondrial swelling. Taken together, these data suggest that Pc 4 is initially aggregated at high local concentration in mitochondria and that irradiation relaxes the quenching of Pc 4 fluorescence through a mechanism that may involve mitochondrial swelling.
Multiple Components of Photodynamic Therapy Can Phosphorylate Akt†
Authors: Bozkulak Ozguncem , Wong Sam , Luna Marian , Ferrario Angela , Rucker Natalie , Gulsoy Murat , Gomer Charles J.
Published: September 2007

A growing number of clinically relevant molecular and cellular responses are observed following photodynamic therapy (PDT). PDT‐mediated oxidative stress and PDT‐induced tissue hypoxia can elicit the transcriptional and/or translational expression of genes associated with cellular stress, inflammation, angiogenesis, immuno‐modulation, apoptosis and signal transduction. One of the signaling molecules activated by oxidative stress is Akt/protein kinase B. Phosphorylation of Akt/protein kinase B activates this signaling molecule and induces a survival response in effected cells and tissue. We hypothesized that PDT using Photofrin (PH) as the photosensitizer could also induce increased levels of Akt phosphorylation. Results from our initial set of experiments demonstrated that in vitro and in vivo PDT treatments induced Akt phosphorylation. Interestingly, incubation of mouse and human breast cancer cells with the porphyrin‐based photosensitizer, PH, increased the expression of Akt phosphorylation in the absence of light. Exposure of the corresponding mouse and human‐derived breast cancer tumors growing in mice to 630 nm light in the absence of PH administration also induced Akt phosphorylation. These results demonstrate that individual components of the PDT process, photosensitizer alone and light alone, as well as the complete PDT procedure can activate the Akt signaling pathway.
Development of a Quantitative Bio/Chemiluminescence Spectrometer Determining Quantum Yields: Re‐examination of the Aqueous Luminol Chemiluminescence Standard
Authors: Ando Yoriko , Niwa Kazuki , Yamada Nobuyuki , Irie Tsutomu , Enomoto Toshiteru , Kubota Hidehiro , Ohmiya Yoshihiro , Akiyama Hidefumi
Published: September 2007

We have developed a bio/chemiluminescence spectrometer with a cooled charge‐coupled‐device (CCD) detector to obtain a quantitative luminescence spectrum as the absolute number of all emitted photons at each wavelength. The integrated area of the spectrum divided by the number of reacted substrate molecules gives the quantum yield. Calibration of the absolute sensitivity of the CCD‐spectrometer system was performed by using lasers and a tungsten lamp with calibrated powers as primary light standards, and calibration of the light‐collection efficiency of the spectrometer with several kinds of cells for liquid samples was achieved by introducing a simple reference double‐plate cell. The reference cell is not convenient for final bio/chemiluminescence measurements but is useful for the calibration because it has well‐defined angular dependence of light emission, allowing accurate calculation of the light‐collection efficiency. Using this CCD‐spectrometer system, we re‐examined the quantum yield of aqueous luminol chemiluminescence with H2O2 catalyzed by horseradish peroxidase. The quantum yield was constant for a wide range of luminol concentrations, whereas it changed and had an optimum against H2O2 concentrations. The optimum quantum yield was 1.23(±0.20)%, which is in good agreement with previously reported values.
Space and the State
Authors: Martin James
Published: September 2007

Speculation over the imminent demise of the nation‐state has recently given way to a more nuanced understanding of its ongoing transformation under globalising conditions. Far from disappearing, argue some, the state is subject to a process of ‘rescaling’ whereby its spatial dimensions are being radically reordered. What is emerging to replace post‐war welfare states is a new and more complex layering of the spaces of governance.
A ‘Rave’ Review: Conceptual Interests and Analytical Shifts in Research on Rave Culture
Authors: Anderson Tammy L. , Kavanaugh Philip R.
Published: September 2007

Raves have historically referred to grassroots organized, antiestablishment and unlicensed all‐night dance parties, featuring electronically produced dance music, such as techno, house, trance and drum and bass. Since their late‐1980s origins in the UK, raves have gained widespread popularity and transformed dramatically. Consequently, their many cultural traits and behaviors have garnered much sociological interest, which mostly falls into two competing perspectives: cultural studies and public health. In this paper, we review what raves look like today compared to their high point in the 1990s. We then discuss how the cultural studies and public health perspectives define raves and have studied them over time, focusing on the ‘pet’ sociological concepts each has sought to advance. Our analysis of these literatures reveals important differences in rave research by country and over time. We end by discussing the politics associated with the shift in rave research.
NMDA receptor‐dependent long‐term potentiation in mouse hippocampal interneurons shows a unique dependence on Ca2+/calmodulin‐dependent kinases
Authors: Lamsa Karri , Irvine Elaine E. , Giese K. Peter , Kullmann Dimitri M.
Published: September 2007

Long‐term potentiation (LTP) of excitatory synaptic transmission plays a major role in memory encoding in the cerebral cortex. It can be elicited at many synapses on principal cells, where it depends on Ca2+ influx through postsynaptic N‐methyl‐d‐aspartic acid (NMDA) receptors. Ca2+ influx triggers phosphorylation of several kinases, in particular Ca2+/calmodulin‐dependent kinase type II (CaMKII). Auto‐phosphorylation of CaMKII is a key step in the LTP induction cascade, as revealed by the absence of LTP in hippocampal pyramidal neurons of αCaMKII T286A‐mutant mice, where auto‐phosphorylation of the α isoform at residue T286 is prevented. A subset of hippocampal interneurons mediating feed‐forward inhibition also exhibit NMDA receptor‐dependent LTP, which shows all the cardinal features of Hebbian LTP in pyramidal neurons. This is unexpected, because αCaMKII has not been detected in interneurons. Here we show that pathway‐specific NMDA receptor‐dependent LTP is intact in hippocampal inhibitory interneurons of αCaMKII T286A‐mutant mice, although in pyramidal cells it is blocked. However, LTP in interneurons is blocked by broad‐spectrum pharmacological inhibition of Ca2+/calmodulin‐dependent kinases. The results suggest that non‐α Ca2+/calmodulin‐dependent kinases substitute for the α isoform in NMDA receptor‐dependent LTP in interneurons.
Sodium‐dependent potassium channels of a Slack‐like subtype contribute to the slow afterhyperpolarization in lamprey spinal neurons
Authors: Wallén Peter , Robertson Brita , Cangiano Lorenzo , Löw Peter , Bhattacharjee Arin , Kaczmarek Leonard K. , Grillner Sten
Published: September 2007

The slow afterhyperpolarization (sAHP) following the action potential is the main determinant of spike frequency regulation. The sAHP after single action potentials in neurons of the lamprey locomotor network is largely due to calcium‐dependent K+ channels (80%), activated by calcium entering the cell during the spike. The residual (20%) component becomes prominent during high level activity (50% of the sAHP). It is not Ca2+ dependent, has a reversal potential like that of potassium, and is not affected by chloride injection. It is not due to rapid activation of Na+/K+‐ATPase. This non‐KCa‐sAHP is reduced markedly in amplitude when sodium ions are replaced by lithium ions, and is thus sodium dependent. Quinidine also blocks this sAHP component, further indicating an involvement of sodium‐dependent potassium channels (KNa). Modulators tested do not influence the KNa‐sAHP amplitude. Immunofluorescence labelling with an anti‐Slack antibody revealed distinct immunoreactivity of medium‐sized and large neurons in the grey matter of the lamprey spinal cord, suggesting the presence of a Slack‐like subtype of KNa channel. The results strongly indicate that a KNa potassium current contributes importantly to the sAHP and thereby to neuronal frequency regulation during high level burst activity as during locomotion. This is, to our knowledge, the first demonstration of a functional role for the Slack gene in contributing to the slow AHP.
Postnatal developmental changes in activation profiles of the respiratory neuronal network in the rat ventral medulla
Authors: Oku Yoshitaka , Masumiya Haruko , Okada Yasumasa
Published: September 2007

Two putative respiratory rhythm generators (RRGs), the para‐facial respiratory group (pFRG) and the pre‐Bötzinger complex (preBötC), have been identified in the neonatal rodent brainstem. To elucidate their functional roles during the neonatal period, we evaluated developmental changes of these RRGs by optical imaging using a voltage‐sensitive dye. Optical signals, recorded from the ventral medulla of brainstem–spinal cord preparations of neonatal (P0–P4) rats (n= 44), were analysed by a cross correlation method. With development during the first few postnatal days, the respiratory‐related activity in the pFRG reduced and shifted from a preinspiratory (P0–P1) to an inspiratory (P2–P4) pattern, whereas preBötC activity remained unchanged. The μ‐opioid agonist [d‐Ala(2),N‐Me‐Phe(4),Gly(5)‐ol]‐enkephalin (DAMGO) augmented preinspiratory activity in the pFRG, while the μ‐opioid antagonist naloxone induced changes in spatiotemporal activation profiles that closely mimicked the developmental changes. These results are consistent with the recently proposed hypothesis by Janczewski and Feldman that the pFRG is activated to compensate for the depression of the preBötC by perinatal opiate surge. We conclude that significant reorganization of the respiratory neuronal network, characterized by a reduction of preinspiratory activity in the pFRG, occurs at P1–P2 in rats. The changes in spatiotemporal activation profiles of the pFRG neurones may reflect changes in the mode of coupling of the two respiratory rhythm generators.
Group III and IV muscle afferents differentially affect the motor cortex and motoneurones in humans
Authors: Martin P. G. , Weerakkody N. , Gandevia S. C. , Taylor J. L.
Published: September 2007

The influence of group III and IV muscle afferents on human motor pathways is poorly understood. We used experimental muscle pain to investigate their effects at cortical and spinal levels. In two studies, electromyographic (EMG) responses in elbow flexors and extensors to stimulation of the motor cortex (MEPs) and corticospinal tract (CMEPs) were evoked before, during, and after infusion of hypertonic saline into biceps brachii to evoke deep pain. In study 1, MEPs and CMEPs were evoked in relaxed muscles and during contractions to a constant elbow flexion force. In study 2, responses were evoked during elbow flexion and extension to a constant level of biceps or triceps brachii EMG, respectively. During pain, the size of CMEPs in relaxed biceps and triceps increased (by ∼47% and ∼56%, respectively; P < 0.05). MEPs did not change with pain, but relative to CMEPs, they decreased in biceps (by ∼34%) and triceps (by ∼43%; P < 0.05). During flexion with constant force, ongoing background EMG and MEPs decreased for biceps during pain (by ∼14% and 15%; P < 0.05). During flexion with a constant EMG level, CMEPs in biceps and triceps increased during pain (by ∼30% and ∼26%, respectively; P < 0.05) and relative to CMEPs, MEPs decreased for both muscles (by ∼20% and ∼17%; P < 0.05). For extension, CMEPs in triceps increased during pain (by ∼22%) whereas MEPs decreased (by ∼15%; P < 0.05). Activity in group III and IV muscle afferents produced by hypertonic saline facilitates motoneurones innervating elbow flexor and extensor muscles but depresses motor cortical cells projecting to these muscles.
The acute effect of stretching on the passive stiffness of the human gastrocnemius muscle tendon unit
Authors: Morse C. I. , Degens H. , Seynnes O. R. , Maganaris C. N. , Jones D. A.
Published: September 2007

Passive stretching is commonly used to increase limb range of movement prior to athletic performance but it is unclear which component of the muscle–tendon unit (MTU) is affected by this procedure. Movement of the myotendinous junction (MTJ) of the gastrocnemius medialis muscle was measured by ultrasonography in eight male participants (20.5 ± 0.9 years) during a standard stretch in which the ankle was passively dorsiflexed at 1 deg s−1 from 0 deg (the foot at right angles to the tibia) to the participants' volitional end range of motion (ROM). Passive torque, muscle fascicle length and pennation angle were also measured. Standard stretch measurements were made before (pre‐) and after (post‐) five passive conditioning stretches. During each conditioning stretch the MTU was taken to the end ROM and held for 1 min. Pre‐conditioning the extension of the MTU during stretch was taken up almost equally by muscle and tendon. Following conditioning, ROM increased by 4.6 ± 1.5 deg (17%) and the passive stiffness of the MTU was reduced (between 20 and 25 deg) by 47% from 16.0 ± 3.6 to 10.2 ± 2.0 Nm deg−1. Distal MTJ displacement (between 0 and 25 deg) increased from 0.92 ± 0.06 to 1.16 ± 0.05 cm, accounting for all the additional MTU elongation and indicating that there was no change in tendon properties. Muscle extension pre‐conditioning was explicable by change in length and pennation angle of the fascicles but post‐conditioning this was not the case suggesting that at least part of the change in muscle with conditioning stretches was due to altered properties of connective tissue.
Generation of a constitutive Na+‐dependent inward‐rectifier current in rat adult atrial myocytes by overexpression of Kir3.4
Authors: Mintert Elisa , Bösche Leif I. , Rinne Andreas , Timpert Mathias , Kienitz Marie‐Cécile , Pott Lutz , Bender Kirsten
Published: September 2007

Apart from gating by interaction with βγ subunits from heterotrimeric G proteins upon stimulation of appropriate receptors, Kir.3 channels have been shown to be gated by intracellular Na+. However, no information is available on how Na+‐dependent gating affects endogenous Kir3.1/Kir3.4 channels in mammalian atrial myocytes. We therefore studied how loading of adult atrial myocytes from rat hearts via the patch pipette filling solution with different concentrations of Na+([Na+]pip) affects Kir3 current. Surprisingly, in a range between 0 and 60 mm, Na+neither had an effect on basal inward‐rectifier current nor on the current activated by acetylcholine. Overexpression of Kir3.4 in adult atrial myocytes forced by adenoviral gene transfer results in formation of functional homomeric channels that interact with βγ subunits upon activation of endogenous muscarinic receptors. These channels are activated at [Na+]pip≥ 15 mm, resulting in a receptor‐independent basal inward rectifier current (Ibir).Ibirwas neither affected by pertussis toxin nor by GDP‐β‐S, suggesting G‐protein‐independent activation. PIP2depletion via endogenous PLC‐coupled α1adrenergic receptors causes inhibition of endogenous Kir3.1/3.4 channel currents by about 75%. In contrast, inhibition of Na+‐activatedIbiramounts to < 20%. The effect of the Kir3 channel blocker tertiapin‐Q can be described using an IC50of 12 nm(endogenousIK(ACh)) and 0.61 nm(Ibir). These data clearly identifyIbiras a homotetrameric Kir3.4 channel current with novel properties of regulation and pharmacology.Ibirshares some properties with a basal current recently described in atrial myocytes from an animal model of atrial fibrillation (AF) and AF patients.
Differential effects of metaboreceptor and chemoreceptor activation on sympathetic and cardiac baroreflex control following exercise in hypoxia in human
Authors: Gujic Marko , Laude Dominique , Houssière Anne , Beloka Sofia , Argacha Jean‐François , Adamopoulos Dionysios , Xhaët Olivier , Elghozi Jean‐Luc , Van De Borne Philippe
Published: September 2007

Muscle metaboreceptors and peripheral chemoreceptors exert differential effects on the cardiorespiratory and autonomic responses following hypoxic exercise. Whether these effects are accompanied by specific changes in sympathetic and cardiac baroreflex control is not known. Sympathetic and cardiac baroreflex functions were assessed by intravenous nitroprusside and phenylephrine boluses in 15 young male subjects. Recordings were performed in random order, under locally circulatory arrested conditions, during: (1) rest and normoxia (no metaboreflex and no chemoreflex activation); (2) normoxic post‐handgrip exercise at 30% of maximum voluntary contraction (metaboreflex activation without chemoreflex activation); (3) hypoxia without handgrip (10% O2 in N2, chemoreflex activation without metaboreflex activation); and (4) post‐handgrip exercise in hypoxia (chemoreflex and metaboreflex activation). When compared with normoxic rest (−42 ± 7% muscle sympathetic nerve activity (MSNA) mmHg−1), sympathetic baroreflex sensitivity did not change during normoxic post‐exercise ischaemia (PEI; −53 ± 9% MSNA mmHg−1, P= 0.5) and increased during resting hypoxia (−68 ± 5% MSNA mmHg−1, P < 0.01). Sympathetic baroreflex sensitivity decreased during PEI in hypoxia (−35 ± 6% MSNA mmHg−1, P < 0.001 versus hypoxia without exercise; P= 0.16 versus normoxic PEI). Conversely, when compared with normoxic rest (11.1 ± 1.7 ms mmHg−1), cardiac baroreflex sensitivity did not change during normoxic PEI (8.3 ± 1.3 ms mmHg−1, P= 0.09), but decreased during resting hypoxia (7.3 ± 0.8 ms mmHg−1, P < 0.05). Cardiac baroreflex sensitivity was lowest during PEI in hypoxia (4.3 ± 1 ms mmHg−1, P < 0.01 versus hypoxia without exercise; P < 0.001 versus normoxic exercise). The metaboreceptors and chemoreceptors exert differential effects on sympathetic and cardiac baroreflex function. Metaboreceptor activation is the major determinant of sympathetic baroreflex sensitivity, when these receptors are stimulated in the presence of hypoxia.
Computer Aided Synthesis of Piecewise Rational Motions for Planar 2R and 3R Robot Arms
Authors: Jin Zhe , Ge Q. J.
Published: September 2007

This paper deals with the problem of synthesizing piecewise rational motions of an object that satisfies kinematic constraints imposed by a planar robot arm with revolute joints. This paper brings together the kinematics of planar robot arms and the recently developed freeform rational motions to study the problem of synthesizing constrained rational motions for Cartesian motion planning. Through the use of planar quaternions, it is shown that for the case of a planar 2R arm, the problem of rational motion synthesis can be reduced to that of circular interpolations in two separate planes and that for the case of a planar 3R arm, the problem can be reduced to a combination of circular interpolation in one plane and a constrained spline interpolation in a circular ring on another plane. Due to the limitation of circular interpolation, only C1 continuous rational motions are generated that satisfy the kinematic constraints exactly. For applications that require C2 continuous motions, this paper presents a method for generating C2 continuous motions that approximate the kinematic constraints for planar 2R and 3R robot arms.
An Explicit Method for Determining the Force-Moment Capabilities of Redundantly Actuated Planar Parallel Manipulators
Authors: Zibil Alp , Firmani Flavio , Nokleby Scott B. , Podhorodeski Ron P.
Published: September 2007

A new explicit methodology for the determination of the force-moment capabilities of nonredundantly and redundantly actuated planar parallel manipulators (PPMs) is presented. This methodology is based on properly adjusting the actuator outputs to their maximum capabilities. As a result, the wrench to be applied or sustained is maximized. For a nonredundantly actuated PPM, one actuator can be maximized, while for a redundantly actuated PPM, one actuator, beyond the one of the nonredundant case, may be maximized for every degree of redundancy added to the mechanism. This methodology is compared to a previous work that required an optimization algorithm. The new method yields more accurate and reliable results and is considerably more efficient. Four studies of force-moment capabilities are considered: maximum force with prescribed moment, maximum applicable force, maximum moment with a prescribed force, and maximum applicable moment. The methodology is used to generate the force-moment capabilities of an existing PPM throughout its workspace.
Design of Compliant Mechanisms for Minimizing Input Power in Dynamic Applications
Authors: Tantanawat Tanakorn , Kota Sridhar
Published: September 2007

In this paper, we investigate power flow in compliant mechanisms that are employed in dynamic applications. More specifically, we identify various elements of the energy storage and transfer between the input, external load, and strain energy stored within the compliant transmission. The goal is to design compliant mechanisms for dynamic applications by exploiting the inherent energy storage capability of compliant mechanisms in the most effective manner. We present a detailed case study on a flapping mechanism, in which we compare the peak input power requirement in a rigid-body mechanism with attached springs versus a distributed compliant mechanism. Through this case study, we present two approaches: (1) generative-load exploitation and (2) reactance cancellation, to describe the role of stored elastic energy in reducing the peak input power requirement. We propose a compliant flapping mechanism and its evaluation using nonlinear transient analysis. The input power needed to drive the proposed compliant flapping mechanism is found to be 50% less than a rigid-link four-bar flapping mechanism without a spring, and 15% less than the one with a spring. This reduction of peak input power is primarily due to the exploitation of elasticity in compliant members. The results show that a compliant mechanism can be a better alternative to a rigid-body mechanism with attached springs.
Synthesis of Bistable Compliant Four-Bar Mechanisms Using Polynomial Homotopy
Authors: Su Hai-Jun , McCarthy J. Michael
Published: September 2007

In this paper we formulate and solve the synthesis equations for a compliant four-bar linkage with three specified equilibrium configurations in the plane. The kinematic synthesis equations as for rigid-body mechanisms are combined with equilibrium constraints at the flexure pivots to form design equations. These equations are simplified by modeling the joint angle variables in the equilibrium equations using sine and cosine functions. Polynomial homotopy continuation is applied to compute all of the design candidates that satisfy these design equations, which are refined using a Newton-Raphson technique. A numerical example demonstrates design methodology in which the homotopy solver obtained eight real solutions. Two of them provide two stable and one unstable equilibrium, and hence, can be used as the prototype of bistable compliant mechanisms.
Micro/Macro or Link-Integrated Micro-actuator Manipulation—A Kinematics and Dynamics Perspective
Authors: Zhang J. , Rastegar J.
Published: September 2007

Smart (active) materials based actuators, hereinafter called micro-actuators, have been shown to be well suited for the elimination of high harmonics in joint and/or end-effector motions of robot manipulators and in the reduction of actuator dynamic response requirements. Low harmonic joint and end-effector motions, as well as low actuator dynamic response requirements, are essential for a robot manipulator to achieve high operating speed and precision with minimal vibration and control problems. Micro-actuators may be positioned at the end-effector to obtain a micro- and macro-robot manipulation configuration. Alternatively, micro-actuators may be integrated into the structure of the links to vary their kinematics parameters, such as their lengths during the motion. In this paper, the kinematics and dynamics consequences of each of the aforementioned alternative are studied for manipulators with serial and closed-loop chains. It is shown that for robot manipulators constructed with closed-loop chains, the high harmonic components of all joint motions can be eliminated only when micro-actuators are integrated into the structure of the closed-loop chain links. The latter configuration is also shown to have dynamics advantage over micro- and macro-manipulator configuration by reducing the potential vibration and control problems at high operating speeds. The conclusions reached in this study also apply to closed-loop chains of parallel and cooperating robot manipulators.
Development of an Integrated System for the Automated Design of a Gerotor Oil Pump
Authors: Chang Y. J. , Kim J. H. , Jeon C. H. , Kim Chul , Jung S. Y.
Published: September 2007

A gerotor pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, construction, and other various applications. In particular, the pump is an essential machine element that feeds lubricant oil in an automotive engine. The main components of the pump are the two rotors. Usually, the outer one is characterized by lobes with a circular shape, while the inner rotor profile is determined as a conjugate to the other. In this study, the design optimization has been carried out to determine the design parameters that maximize the specific flow rate and minimize the flow rate irregularity. The integrated system, which is composed of three main modules, has been developed through AutoLISP, Visual Basic language, and the CAD method, and considers various design parameters. An optimally designed model for a general type of gerotor pump has been generated and experimentally verified for its pump performances. Results obtained using the system enable the designer and manufacturer of the oil pump to be more efficient in this field.
Mixed-Layer Deepening During Heinrich Events: A Multi-Planktonic Foraminiferal δ
18
O Approach
Authors: Rashid Harunur , Boyle Edward A.
Published: September 2007

Proxies from Greenland ice cores and North Atlantic marine sediment cores document repeated extreme climate swings of a few decades to millennia during the last glacial cycle, including periods of intense ice rafting called Heinrich events (HEs). We have found similar oxygen isotope variations recorded in mixed-layer–and thermocline-dwelling planktonic foraminifera during HEs 0, 1, and 4, suggesting that three foraminiferal taxa calcified their shells at similar temperatures in a homogenized upperwater column. This implies that the surface mixed layer was deeper during HEs. Similar deepening occurred on the northern margin of the ice-rafted–debris belt, implying that these deep mixed layers during HEs were widespread in the region. We suggest that an increase in storminess during HEs intensified the vertical mixing of meltwater from ice rafting in the upper ocean.
ON COMPUTING LONGEST PATHS IN SMALL GRAPH CLASSES
Authors: UEHARA RYUHEI , UNO YUSHI
Published: September 2007

The longest path problem is the one that finds a longest path in a given graph. While the graph classes in which the Hamiltonian path problem can be solved efficiently are widely investigated, few graph classes are known to be solved efficiently for the longest path problem. Among those, for trees, a simple linear time algorithm for the longest path problem is known. We first generalize the algorithm, and show that the longest path problem can be solved efficiently for some tree-like graph classes by this approach. We next propose two new graph classes that have natural interval representations, and show that the longest path problem can be solved efficiently on these classes.
UNDECIDABILITY BOUNDS FOR INTEGER MATRICES USING CLAUS INSTANCES
Authors: HALAVA VESA , HARJU TERO , HIRVENSALO MIKA
Published: September 2007

There are several known undecidable problems for 3 × 3 integer matrices the proof of which use a reduction from the Post Correspondence Problem (PCP). We establish new lower bounds in the number of matrices for the mortality, zero in the left upper corner, vector reachability, matrix reachability, scalar reachability and freeness problems. Also, we give a short proof for a strengthened result due to Bell and Potapov stating that the membership problem is undecidable for finitely generated matrix semigroups R ⊆ ℤ 4×4 whether or not kI4 ∈ R for any given |k| > 1. These bounds are obtained by using the Claus instances of the PCP.
ON THE EXISTENCE OF LOOKAHEAD DELEGATORS FOR NFA
Authors: RAVIKUMAR BALA , SANTEAN NICOLAE
Published: September 2007

We investigate deterministically simulating (i.e., solving the membership problem for) nondeterministic finite automata (NFA), relying solely on the NFA's resources (states and transitions). Unlike the standard NFA simulation, involving an algorithm which stores at each step all the states reached nondeterministically while reading the input, we consider deterministic finite automata (DFA) with lookahead, which choose the “right” NFA transitions based on a fixed number of input symbols read ahead. This concept, known as lookahead delegation, arose in a formal study of web services composition and its subsequent practical applications. Here we answer several related questions, such as “when is lookahead delegation possible?” and “how hard is it to find a delegator with a given lookahead buffer size?”. In particular, we show that only finite languages have the property that all their NFA have delegators. This implies, among others, that delegation is a machine property, rather than a language property. We also prove that the existence of lookahead delegators for unambiguous NFA is decidable, thus partially solving an open problem. Finally, we show that finding delegators (even for a given buffer size) is hard in general, and is more efficient for unambiguous NFA, and we give an algorithm and a compact characterization for NFA delegation in general.
ON THE EFFECT OF VARIABLE IDENTIFICATION ON THE ESSENTIAL ARITY OF FUNCTIONS ON FINITE SETS
Authors: COUCEIRO MIGUEL , LEHTONEN ERKKO
Published: September 2007

We show that every function of several variables on a finite set of k elements with n > k essential variables has a variable identification minor with at least n − k essential variables. This is a generalization of a theorem of Salomaa on the essential variables of Boolean functions. We also strengthen Salomaa's theorem by characterizing all the Boolean functions f having a variable identification minor that has just one essential variable less than f.
EFFICIENT ID-BASED MULTI-RECEIVER THRESHOLD DECRYPTION
Authors: CHAI ZHENCHUAN , CAO ZHENFU , DONG XIAOLEI
Published: September 2007

Threshold decryption allows a message encrypted under a public key to be read only when a quorum of users cooperate to decrypt the ciphertext. However, such threshold decryption scheme does not apply well in the situation where all the users have their own public/private key pairs, but not share any private key associated with a public key, such as mobile ad hoc network featured by its dynamic character. An immediate way to achieve threshold decryption in this situation is to split the message into pieces, then encrypt these pieces under the public keys of different users. However, it is not efficient. In this paper, we propose an efficient identity based multi-receiver threshold decryption scheme that could be applied efficiently in the above situation. We also define the security notions and prove the security in random oracle model. At last, we add the broadcast feature to the scheme, such that a message could be broadcast to any number of groups.
FAULT RESILIENCY OF CAYLEY GRAPHS GENERATED BY TRANSPOSITIONS
Authors: CHENG EDDIE , LIPTÁK LÁSZLÓ
Published: September 2007

The star graph Sn, proposed by [1], has many advantages over the n-cube. It is shown in [2] that when a large number of vertices are deleted from Sn, the resulting graph can have at most two components, one of which is small. In this paper, we show that Cayley graphs generated by transpositions have this property.
APPLICATION PLACEMENT ON A CLUSTER OF SERVERS
Authors: URGAONKAR BHUVAN , ROSENBERG ARNOLD L. , SHENOY PRASHANT
Published: September 2007

The APPLICATION PLACEMENT PROBLEM (APP, for short) arises in hosting platforms: clusters of servers that are used for hosting large, distributed applications such as Internet services. Hosting platforms imply a business relationship between an entity called the platform provider and a number of entities called the application providers. The latter pay the former for the resources on the hosting platform, in return for which, the former provides guarantees on resource availability for the applications. This implies that a hosting platform should host only applications for which it has sufficient resources. The objective of the APP is to maximize the number of applications that can be hosted on the platform while satisfying their resource requirements. The complexity of the APP is studied here, with the following results. The general APP is NP-hard; indeed, even restricted versions of the APP may not admit polynomial-time approximation schemes. However, several significant variants of the online version of the APP admit efficient approximation algorithms.
A FRAMEWORK FOR SOLVING SEQUENCE PROBLEM OF MULTIPLE INPUT STREAMS
Authors: LIN CHO-CHIN
Published: September 2007

In this research, a framework is proposed for answering the question: whether a dominant sequence exists for the multiple self-contained input streams destined for a computation provider running the requested applications concurrently. The framework is extended to find an optimal semidominant sequence for multiple input streams. This paper also shows that an existent universal dominant sequence can be formed by permuting a set of dominant input streams. In this paper, the neighbor-connected graph is first proposed to model the sequence problem of multiple input streams. Then, an algorithm with time complexity O(nLn) is proposed to determine the existence of a dominant data-receiving sequence, where L is the maximal length of the input streams plus one and n is the number of input streams. Examples of applying the framework to solve the sequence problems for several computation-intensive applications are also given. Furthermore, the framework is extended to find an optimal semidominant sequence using an algorithm with time complexity O(nLnlogδ*), where δ* is the maximal degree that the sequence diverges from all the optimal subsequences. Finally, the property of a universal dominant sequence is studied and the performance of the sequence is compared with those of other sequences.
REPRESENTATION OF SEMIAUTOMATA BY CANONICAL WORDS AND EQUIVALENCES, PART II: SPECIFICATION OF SOFTWARE MODULES
Authors: BRZOZOWSKI JANUSZ , JÜRGENSEN HELMUT
Published: September 2007

A theory of representation of semiautomata by canonical words and equivalences was developed in [7]. That work was motivated by trace-assertion specifications of software modules, but its focus was entirely on the underlying mathematical model. In the present paper we extend that theory to automata with Moore and Mealy outputs, and show how to apply the extended theory to the specification of modules. In particular, we present a unified view of the trace-assertion methodology, as guided by our theory. We illustrate this approach, and some specific issues, using several nontrivial examples. We include a discussion of finite versus infinite modules, methods of error handling, some awkward features of the trace-assertion method, and a comparison to specifications by automata. While specifications by trace assertions and automata are equivalent in power, there are cases where one approach appears to be more natural than the other. We conclude that, for certain types of system modules, formal specification by automata, as opposed to informal state machines, is not only possible, but practical.