bluuebunny/crossref_metadata_2025 huggingface dataset:
Leptin, skeletal muscle lipids, and lipid-induced insulin resistance
Authors: Dube John J. , Bhatt Bankim A. , Dedousis Nikolas , Bonen Arend , O'Doherty Robert M.
Published: May 2007

Leptin-induced increases in insulin sensitivity are well established and may be related to the effects of leptin on lipid metabolism. However, the effects of leptin on the levels of lipid metabolites implicated in pathogenesis of insulin resistance and the effects of leptin on lipid-induced insulin resistance are unknown. The current study addressed in rats the effects of hyperleptinemia (HL) on insulin action and markers of skeletal muscle (SkM) lipid metabolism in the absence or presence of acute hyperlipidemia induced by an infusion of a lipid emulsion. Compared with controls (CONT), HL increased insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamp (∼15%), and increased SkM Akt (∼30%) and glycogen synthase kinase 3α (∼52%) phosphorylation. These improvements in insulin action were associated with decreased SkM triglycerides (TG; ∼61%), elevated ceramides (∼50%), and similar diacylglycerol (DAG) levels in HL compared with CONT. Acute hyperlipidemia in CONT decreased insulin sensitivity (∼25%) and increased SkM DAG (∼33%) and ceramide (∼60%) levels. However, hyperlipidemia did not induce insulin resistance or SkM DAG and ceramide accumulation in HL. SkM total fatty acid transporter CD36, plasma membrane fatty acid binding protein, acetyl Co-A carboxylase phosphorylation, and fatty acid oxidation were similar in HL compared with CONT. However, HL decreased SkM protein kinase Cθ (PKCθ), a kinase implicated in mediating the detrimental effects of lipids on insulin action. We conclude that increases in insulin sensitivity induced by HL are associated with decreased levels of SkM TG and PKCθ and increased SkM insulin signaling, but not with decreases in other lipid metabolites implicated in altering SkM insulin sensitivity (DAG and ceramide). Furthermore, insulin resistance induced by an acute lipid infusion is prevented by HL.
Prenatal high-salt diet in the Sprague-Dawley rat programs blood pressure and heart rate hyperresponsiveness to stress in adult female offspring
Authors: Porter James P. , King Summer H. , Honeycutt April D.
Published: May 2007

Several animal models have been developed to study fetal programming of hypertension. One model involves feeding high-salt (HS) diet to rats before and during pregnancy, during lactation, and after weaning for 10 days. In the present investigation, we limited HS diet to the prenatal period in an attempt to find a narrower critical window for fetal programming. The HS diet did not result in low-birth weight offspring. In the adult offspring, radiotelemetry was used to assess blood pressure and heart rate in the conscious unstressed state. As adults, the HS offspring were not hypertensive compared with normal-salt (NS) control animals. However, the pressor and tachycardic responses to 1-h of restraint were significantly enhanced in HS female offspring, and recovery after restraint was delayed. This was accompanied by an increase in relative expression of corticotropin-releasing hormone (CRH) mRNA in the paraventricular nucleus of the hypothalamus during basal and stressed conditions. There was no augmented stress response or relative increase in CRH mRNA in adult HS male offspring. When challenged with 1 wk of 8% NaCl diet as adults, neither HS male nor female offspring exhibited salt sensitivity compared with NS groups. These data show that a high-salt diet limited to the prenatal period is not sufficient to program hypertension in adult offspring. However, this narrower critical period is sufficient to imprint a lasting hyperresponsiveness to stress, at least in adult female offspring. These data indicate that excessive maternal salt intake during pregnancy can adversely affect the cardiovascular health of adult offspring.
Combined proteomic and metabonomic studies in three genetic forms of the renal Fanconi syndrome
Authors: Vilasi Annalisa , Cutillas Pedro R. , Maher Anthony D. , Zirah Severine F. M. , Capasso Giovambattista , Norden Anthony W. G. , Holmes Elaine , Nicholson Jeremy K. , Unwin Robert J.
Published: May 2007

The renal Fanconi syndrome is a defect of proximal tubular function causing aminoaciduria and low-molecular-weight proteinuria. Dent's disease and Lowe syndrome are defined X-linked forms of Fanconi syndrome; there is also an autosomal dominant idiopathic form (ADIF), phenotypically similar to Dent's disease though its gene defect is still unknown. To assess whether their respective gene products are ultimately involved in a common reabsorptive pathway for proteins and low-molecular-mass endogenous metabolites, we compared renal Fanconi urinary proteomes and metabonomes with normal (control) urine using mass spectrometry and1H-NMR spectroscopy, respectively. Urine from patients with low-molecular-weight proteinuria secondary to ifosfamide treatment (tubular proteinuria; TP) was also analyzed for comparison. All four of the disorders studied had characteristic proteomic and metabonomic profiles. Uromodulin was the most abundant protein in normal urine, whereas Fanconi urine was dominated by albumin.1H-NMR spectroscopic data showed differences in the metabolic profiles of Fanconi urine vs. normal urine, due mainly to aminoaciduria. There were differences in the urinary metabolite and protein compositions between the three genetic forms of Fanconi syndrome: cluster analysis grouped the Lowe and Dent's urinary proteomes and metabonomes together, whereas ADIF and TP clustered together separately. Our findings demonstrate a distinctive “polypeptide and metabolite fingerprint” that can characterize the renal Fanconi syndrome; they also suggest that more subtle and cause-specific differences may exist between the different forms of Fanconi syndrome that might provide novel insights into the underlying mechanisms and cellular pathways affected.
Epoxyeicosatrienoic acids affect electrolyte transport in renal tubular epithelial cells: dependence on cyclooxygenase and cell polarity
Authors: Nüsing Rolf M. , Schweer Horst , Fleming Ingrid , Zeldin Darryl C. , Wegmann Markus
Published: May 2007

We investigated the effects of epoxyeicosatrienoic acids (EETs) on ion transport in the polarized renal distal tubular cell line, Madin-Darby canine kidney (MDCK) C7. Of the four EET regioisomers (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) studied, only apical, but not basolateral, application of 5,6-EET increased short-circuit current ( Isc) with kinetics similar to those of arachidonic acid. The ion transport was blocked by preincubation with the cyclooxygenase inhibitor indomethacin or with the chloride channel blocker NPPB. Furthermore, both a Cl−-free bath solution and the Ca2+antagonist verapamil blocked 5,6-EET-induced ion transport. Although the presence of the PGE2receptors EP2, EP3, and EP4 was demonstrated, apically added PGE2was ineffective and basolaterally added PGE2caused a different kinetics in ion transport compared with 5,6-EET. Moreover, PGE2sythesis in MDCK C7 cells was unaffected by 5,6-EET treatment. GC/MS/MS analysis of cell supernatants revealed the presence of the biologically inactive 5,6-dihydroxy-PGE1in 5,6-EET-treated cells, but not in control cells. Indomethacin suppressed the formation of 5,6-dihydroxy-PGE1. 5,6-Epoxy-PGE1, the precursor of 5,6-dihydroxy-PGE1, caused a similar ion transport as 5,6-EET. Cytochrome P-450 enzymes homolog to human CYP2C8, CYP2C9, and CYP2J2 protein were detected immunologically in the MDCK C7 cells. Our findings suggest that 5,6-EET affects Cl−transport in renal distal tubular cells independent of PGE2but by a mechanism, dependent on its conversion to 5,6-epoxy-PGE1by cyclooxygenase. We suggest a role for this P450 epoxygenase product in the regulation of electrolyte transport, especially as a saluretic compound acting from the luminal side of tubular cells in the mammalian kidney.
Prior exercise speeds pulmonary O2 uptake kinetics by increases in both local muscle O2 availability and O2 utilization
Authors: DeLorey Darren S. , Kowalchuk John M. , Heenan Aaron P. , duManoir Gregory R. , Paterson Donald H.
Published: May 2007

The effect of prior exercise on pulmonary O2 uptake (V̇o2p), leg blood flow (LBF), and muscle deoxygenation at the onset of heavy-intensity alternate-leg knee-extension (KE) exercise was examined. Seven subjects [27 ( 5 ) yr; mean (SD)] performed step transitions ( n = 3; 8 min) from passive KE following no warm-up (HVY 1) and heavy-intensity (Δ50%, 8 min; HVY 2) KE exercise. V̇o2p was measured breath-by-breath; LBF was measured by Doppler ultrasound at the femoral artery; and oxy (O2Hb)-, deoxy (HHb)-, and total (Hbtot) hemoglobin/myoglobin of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). Phase 2 V̇o2p, LBF, and HHb data were fit with a monoexponential model. The time delay (TD) from exercise onset to an increase in HHb was also determined and an HHb effective time constant (HHb − MRT = TD + τ) was calculated. Prior heavy-intensity exercise resulted in a speeding ( P < 0.05) of phase 2 V̇o2p kinetics [HVY 1: 42 s ( 6 ); HVY 2: 37 s ( 8 )], with no change in the phase 2 amplitude [HVY 1: 1.43 l/min (0.21); HVY 2: 1.48 l/min (0.21)] or amplitude of the V̇o2p slow component [HVY 1: 0.18 l/min (0.08); HVY 2: 0.18 l/min (0.09)]. O2Hb and Hbtot were elevated throughout the on-transient following prior heavy-intensity exercise. The τLBF [HVY 1: 39 s ( 7 ); HVY 2: 47 s ( 21 ); P = 0.48] and HHb-MRT [HVY 1: 23 s ( 4 ); HVY 2: 21 s ( 7 ); P = 0.63] were unaffected by prior exercise. However, the increase in HHb [HVY 1: 21 μM ( 10 ); HVY 2: 25 μM ( 10 ); P < 0.001] and the HHb-to-V̇o2p ratio [(HHb/V̇o2p) HVY 1: 14 μM·l−1·min−1 ( 6 ); HVY 2: 17 μM·l−1·min−1 ( 5 ); P < 0.05] were greater following prior heavy-intensity exercise. These results suggest that the speeding of phase 2 τV̇o2p was the result of both elevated local O2 availability and greater O2 extraction evidenced by the greater HHb amplitude and HHb/V̇o2p ratio following prior heavy-intensity exercise.
Methacholine responsiveness in mice from 2 to 8 wk of age
Authors: Bozanich Elizabeth M. , Jánosi Tibor Z. , Collins Rachel A. , Thamrin Cindy , Turner Debra J. , Hantos Zoltán , Sly Peter D.
Published: May 2007

Many chronic human lung diseases have their origin in early childhood, yet most murine models used to study them utilize adult mice. An important component of the asthma phenotype is exaggerated airway responses, frequently modelled by methacholine (MCh) challenge. The present study was undertaken to characterize MCh responses in mice from 2 to 8 wk of age measuring absolute lung volume and volume-corrected respiratory mechanics as outcome variables. Female BALB/c mice aged 2, 3, 4, 6, and 8 wk were studied during cumulative intravenous MCh challenge. Following each MCh dose, absolute lung volume was measured plethysmographically at functional residual volume and during a slow inflation to 20-hPa transrespiratory pressure. Respiratory system impedance was measured continuously during the inflation maneuver and partitioned into airway and constant-phase parenchymal components by model fitting. Volume-corrected (specific) estimates of respiratory mechanics were calculated. Intravenous MCh challenge induced a predominantly airway response with no evidence of airway closure in any age group. No changes in functional residual volume were seen in mice of any age during the MCh challenge. The specific airway resistance MCh dose response curves did not show significant differences between the age groups. The results from the present study do not show systematic differences in MCh responsiveness in mice from 2 to 8 wk of age.
Prehension Synergies in the Grasps With Complex Friction Patterns: Local Versus Synergic Effects and the Template Control
Authors: Niu Xun , Latash Mark L. , Zatsiorsky Vladimir M.
Published: May 2007

We studied adjustments of digit forces to changes in the friction. The subjects held a handle statically in a three-digit grasp. The friction under each digit was either high or low, resulting in eight three-element friction sets (such grasps were coined the grasps with complex friction pattern). The total load was also manipulated. It was found that digit forces were adjusted not only to the supported load and local friction, but also to friction at other digits (synergic effects). When friction under a digit was low, its tangential force decreased and the normal force increased (local effects). The synergic effects were directed to maintain the equilibrium of the handle. The relation between the individual digit forces and loads agreed with the triple-product model: fin= ki(2)ki(1)L, where finis normal force of digit i, L is the load (newtons), ki(1)is a dimensionless coefficient representing sharing the total tangential force among the digits (∑ ki(1)= 1.0), and ki(2)is a coefficient representing the relation between the tangential and normal forces of digit i (the overall friction equivalent, OFE). At each friction set, the central controller selected the grasping template—a three-element array of ki(2)ki(1)products—and then scaled the template with the load magnitude.
In Vivo Roles for Matrix Metalloproteinase-9 in Mature Hippocampal Synaptic Physiology and Plasticity
Authors: Bozdagi Ozlem , Nagy Vanja , Kwei Kimberly T. , Huntley George W.
Published: May 2007

Extracellular proteolysis is an important regulatory nexus for coordinating synaptic functional and structural plasticity, but the identity of such proteases is incompletely understood. Matrix metalloproteinases (MMPs) have well-known, mostly deleterious roles in remodeling after injury or stroke, but their role in nonpathological synaptic plasticity and function in intact adult brains has not been extensively investigated. Here we address the role of MMP-9 in hippocampal synaptic plasticity using both gain- and loss-of-function approaches in urethane-anesthetized adult rats. Acute blockade of MMP-9 proteolytic activity with inhibitors or neutralizing antibodies impairs maintenance, but not induction, of long-term potentiation (LTP) at synapses formed between Schaffer-collaterals and area CA1 dendrites. LTP is associated with significant increases in levels of MMP-9 and proteolytic activity within the potentiated neuropil. By introducing a novel application of gelatin-substrate zymography in vivo, we find that LTP is associated with significantly elevated numbers of gelatinolytic puncta in the potentiated neuropil that codistribute with immunolabeling for MMP-9 and for markers of synapses and dendrites. Such increases in proteolytic activity require NMDA receptor activation. Exposing intact area CA1 neurons to recombinant-active MMP-9 induces a slow synaptic potentiation that mutually occludes, and is occluded by, tetanically evoked potentiation. Taken together, our data reveal novel roles for MMP-mediated proteolysis in regulating nonpathological synaptic function and plasticity in mature hippocampus.
Synaptic Vesicle Distribution and Release at Rat Diaphragm Neuromuscular Junctions
Authors: Rowley Katharine L. , Mantilla Carlos B. , Ermilov Leonid G. , Sieck Gary C.
Published: May 2007

Synaptic vesicle release at the neuromuscular junction (NMJ) is highly reliable and is vital to the success of synaptic transmission. We examined synaptic vesicle number, distribution, and release at individual type-identified rat diaphragm NMJ. Three-dimensional reconstructions of electron microscopy images were used to obtain novel measurements of active zone distribution and the number of docked synaptic vesicles. Diaphragm muscle-phrenic nerve preparations were used to perform electrophysiological measurements of the decline in quantal content (QC) during repetitive phrenic nerve stimulation. The number of synaptic vesicles available for release vastly exceeds those released with a single stimulus, thus reflecting a relatively low probability of release for individual docked vesicles and at each active zone. There are two components that describe the decline in QC resulting from repetitive stimulation: a rapid phase (<0.5 s) and a delayed phase (<2.5 s). Differences in the initial rapid decline in QC were evident across type-identified presynaptic terminals (fiber type classification based on myosin heavy chain composition). At terminals innervating type IIx and/or IIb fibers, the initial decline in QC during repetitive stimulation matched the predicted depletion of docked synaptic vesicles. In contrast, at terminals innervating type I or IIa fibers, a faster than predicted decline in QC with repetitive stimulation suggests that a decrease in the probability of release at these terminals plays a role in addition to depletion of docked vesicles. Differences in QC decline likely reflect fiber-type specific differences in activation history and correspond with well-described differences in neuromuscular transmission across muscle fiber types.
Multichannel Micromanipulator and Chamber System for Recording Multineuronal Activity in Alert, Non-Human Primates
Authors: Gray Charles M. , Goodell Baldwin , Lear Alex
Published: May 2007

We describe the design and performance of an electromechanical system for conducting multineuron recording experiments in alert non-human primates. The system is based on a simple design, consisting of a microdrive, control electronics, software, and a unique type of recording chamber. The microdrive consists of an aluminum frame, a set of eight linear actuators driven by computer-controlled miniature stepping motors, and two printed circuit boards (PCBs) that provide connectivity to the electrodes and the control electronics. The control circuitry is structured around an Atmel RISC-based microcontroller, which sends commands to as many as eight motor control cards, each capable of controlling eight motors. The microcontroller is programmed in C and uses serial communication to interface with a host computer. The graphical user interface for sending commands is written in C and runs on a conventional personal computer. The recording chamber is low in profile, mounts within a circular craniotomy, and incorporates a removable internal sleeve. A replaceable Sylastic membrane can be stretched across the bottom opening of the sleeve to provide a watertight seal between the cranial cavity and the external environment. This greatly reduces the susceptibility to infection, nearly eliminates the need for routine cleaning, and permits repeated introduction of electrodes into the brain at the same sites while maintaining the watertight seal. The system is reliable, easy to use, and has several advantages over other commercially available systems with similar capabilities.
Modulation of a Delayed-Rectifier K+ Current by Angiotensin II in Rat Sympathetic Neurons
Authors: Acosta Eduardo , Mendoza Víctor , Castro Elena , Cruzblanca Humberto
Published: May 2007

It is well known that angiotensin II (Angio II) mimics most of the muscarinic-mediated excitatory actions of acetylcholine on superior cervical ganglion neurons. For instance, in addition to depolarization and stimulation of norepinephrine release, muscarinic agonists and Angio II modulate the M-type K+ current and the N-type Ca2+ current. We recently found that muscarinic receptors modulate the delayed rectifier current IKV as well. Therefore a whole cell patch-clamp experiment was carried out in rat cultured sympathetic neurons to assess whether Angio II modulates IKV. We found that Angio II increased IKV by about 30% with a time constant of approximately 30 s. In comparison, inhibition of M-current was faster (τ ∼ 8 s) and stronger (∼61%). Modulation of IKV was disrupted by the AT1 receptor-antagonist losartan but not by the AT2-antagonist PD123319. IKV enhancement was reduced by the G-protein inhibitor GDP-β-S, whereas current modulation remained unaltered after cell treatment with pertussis toxin. The peptidergic modulation of IKV was severely disrupted when internal ATP was replaced by its nonhydrolyzable analogue AMP-PNP. Angio II enhanced IKV and further reduced the stimulatory action of a muscarinic agonist on IKV. Likewise, the muscarinc agonist enhanced IKV and occluded the effect of Angio II on IKV. We have also found that the protein kinase C activator PMA enhanced IKV, thereby mimicking and further attenuating the action of Angio II on IKV. These results suggest that AT1 receptors by coupling to pertussis toxin–insensitive G proteins, stimulate an ATP-dependent and PKC-mediated pathway to modulate IKV.
Multimodality Data Integration in Epilepsy
Authors: Muzik Otto , Chugani Diane C. , Zou Guangyu , Hua Jing , Lu Yi , Lu Shiyong , Asano Eishi , Chugani Harry T.
Published: May 2007

An important goal of software development in the medical field is the design of methods which are able to integrate information obtained from various imaging and nonimaging modalities into a cohesive framework in order to understand the results of qualitatively different measurements in a larger context. Moreover, it is essential to assess the various features of the data quantitatively so that relationships in anatomical and functional domains between complementing modalities can be expressed mathematically. This paper presents a clinically feasible software environment for the quantitative assessment of the relationship among biochemical functions as assessed by PET imaging and electrophysiological parameters derived from intracranial EEG. Based on the developed software tools, quantitative results obtained from individual modalities can be merged into a data structure allowing a consistent framework for advanced data mining techniques and 3D visualization. Moreover, an effort was made to derive quantitative variables (such as the spatial proximity index, SPI) characterizing the relationship between complementing modalities on a more generic level as a prerequisite for efficient data mining strategies. We describe the implementation of this software environment in twelve children (mean age 5.2 ± 4.3 years) with medically intractable partial epilepsy who underwent both high‐resolution structural MR and functional PET imaging. Our experiments demonstrate that our approach will lead to a better understanding of the mechanisms of epileptogenesis and might ultimately have an impact on treatment. Moreover, our software environment holds promise to be useful in many other neurological disorders, where integration of multimodality data is crucial for a better understanding of the underlying disease mechanisms.
Regular Generalizedω-Closed Sets
Authors: Al-Omari Ahmad , Noorani Mohd Salmi Md
Published: May 2007

In 1982 and 1970, Hdeib and Levine introduced the notions ofω-closed set and generalized closed set, respectively. The aim of this paper is to provide a relatively new notion of generalized closed set, namely, regular generalizedω-closed, regular generalizedω-continuous,a-ω-continuous, and regular generalizedω-irresolute maps and to study its fundamental properties.
On the Behaviour of the Solutions of a Second-Order Difference Equation
Authors: Gutnik Leonid , Stevic Stevo
Published: May 2007

We study the difference equationxn+1=α−xn/xn−1,n∈ℕ0, whereα∈ℝand wherex−1andx0are so chosen that the corresponding solution(xn)of the equation is defined for everyn∈ℕ. We prove that whenα=3the equilibriumx¯=2of the equation is not stable, which corrects a result due to X. X. Yan, W. T. Li, and Z. Zhao. For the caseα=1, we show that there is a strictly monotone solution of the equation, and we also find its asymptotics. An explicit formula for the solutions of the equation are given for the caseα=0.
Rational Probabilistic Deciders—Part I: Individual Behavior
Authors: Kabamba P. T. , Lin W.-C. , Meerkov S. M.
Published: May 2007

This paper is intended to model a decision maker as a rational probabilistic decider (RPD) and to investigate its behavior in stationary and symmetric Markov switch environments. RPDs take their decisions based on penalty functions defined by the environment. The quality of decision making depends on a parameter referred to as level of rationality. The dynamic behavior of RPDs is described by an ergodic Markov chain. Two classes of RPDs are considered—local and global. The former take their decisions based on the penalty in the current state while the latter consider all states. It is shown that asymptotically (in time and in the level of rationality) both classes behave quite similarly. However, the second largest eigenvalue of Markov transition matrices for global RPDs is smaller than that for local ones, indicating faster convergence to the optimal state. As an illustration, the behavior of a chief executive officer, modeled as a global RPD, is considered, and it is shown that the company performance may or may not be optimized—depending on the pay structure employed. While the current paper investigates individual RPDs, a companion paper will address collective behavior.
Bitraces on PartialO*-Algebras
Authors: Ekhaguere G. O. S.
Published: May 2007

Unbounded bitraces on partialO*-algebras are considered, a class of ideals defined by them is exhibited, and several relationships between certain commutants, bicommutants, and tricommutants associated with the*-representations and*-antirepresentations determined by the bitraces are established. Moreover, a notion of a partialW*-algebra of unbounded densely defined linear maps on a Hilbert space, as a generalization of aW*-algebra, is introduced and a set of criteria for classifying such algebras by means of the type of bitraces that are defined on them is proposed.
Role ofp53andCDKN2AInactivation in Human Squamous Cell Carcinomas
Authors: Pacifico Alessia , Leone Giovanni
Published: May 2007

p53tumor suppressor gene is the most commonly mutated gene in human and mouse cancers. Disruption of thep53andRbpathways is a fundamental trend of most human cancer cells. Inactivation ofCDKN2Acan lead to deregulation of these two pathways. Genetic abnormalities inCDKN2Agene have been well documented in human melanoma but their involvement in human nonmelanoma skin cancer (NMSC) and in particular in squamous cell carcinoma (SCC) is less clear. Several studies have shown that human SCCs harbour unique mutations in thep53gene as well as inactivation of theCDKN2Agene. While mutations in thep53gene are induced by UV radiation and represent tumor initiating events, the majority of alterations detected in theCDKN2Agene do not appear to be UV-dependent. In conclusion, in addition top53mutations, silencing of theCDKN2Agene might play a significant role in SCC development.
High-Performance Long NoC Link Using Delay-Insensitive Current-Mode Signaling
Authors: Nigussie Ethiopia , Lehtonen Teijo , Tuuna Sampo , Plosila Juha , Isoaho Jouni
Published: May 2007

High-performance long-range NoC link enables efficient implementation of network-on-chip topologies which inherently require high-performance long-distance point-to-point communication such as torus and fat-tree structures. In addition, the performance of other topologies, such as mesh, can be improved by using high-performance link between few selected remote nodes. We presented novel implementation of high-performance long-range NoC link based on multilevel current-mode signaling and delay-insensitive two-phase 1-of-4 encoding. Current-mode signaling reduces the communication latency of long wires significantly compared to voltage-mode signaling, making it possible to achieve high throughput without pipelining and/or using repeaters. The performance of the proposed multilevel current-mode interconnect is analyzed and compared with two reference voltage mode interconnects. These two reference interconnects are designed using two-phase 1-of-4 encoded voltage-mode signaling, one with pipeline stages and the other using optimal repeater insertion. The proposed multilevel current-mode interconnect achieves higher throughput and lower latency than the two reference interconnects. Its throughput at 8 mm wire length is 1.222 GWord/s which is 1.58 and 1.89 times higher than the pipelined and optimal repeater insertion interconnects, respectively. Furthermore, its power consumption is less than the optimal repeater insertion voltage-mode interconnect, at 10 mm wire length its power consumption is 0.75 mW while the reference repeater insertion interconnect is 1.066 mW. The effect of crosstalk is analyzed using four-bit parallel data transfer with the best-case and worst-case switching patterns and a transmission line model which has both capacitive coupling and inductive coupling.
eGenomics: Cataloguing Our Complete Genome Collection III
Authors: Field Dawn , Garrity George , Gray Tanya , Selengut Jeremy , Sterk Peter , Thomson Nick , Tatusova Tatiana , Cochrane Guy , Glöckner Frank Oliver , Kottmann Renzo , Lister Allyson L. , Tateno Yoshio , Vaughan Robert
Published: May 2007

This meeting report summarizes the proceedings of the “eGenomics: Cataloguing our Complete Genome Collection III” workshop held September 11–13, 2006, at the National Institute for EnvironmentaleScience (NIEeS), Cambridge, United Kingdom. This 3rd workshop of the Genomic Standards Consortium was divided into two parts. The first half of the three-day workshop was dedicated to reviewing the genomic diversity of our current and future genome and metagenome collection, and exploring linkages to a series of existing projects through formal presentations. The second half was dedicated to strategic discussions. Outcomes of the workshop include a revised “Minimum Information about a Genome Sequence” (MIGS) specification (v1.1), consensus on a variety of features to be added to the Genome Catalogue (GCat), agreement by several researchers to adopt MIGS for imminent genome publications, and an agreement by the EBI and NCBI to input their genome collections into GCat for the purpose of quantifying the amount of optional data already available (e.g., for geographic location coordinates) and working towards a single, global list of all public genomes and metagenomes.
A Spatially Extended Model for Residential Segregation
Authors: Aguilera Antonio , Ugalde Edgardo
Published: May 2007

We analyze urban spatial segregation phenomenon in terms of the income distribution over a population, and an inflationary parameter weighting the evolution of housing prices. For this, we develop a discrete spatially extended model based on a multiagent approach. In our model, the mobility of socioeconomic agents is driven only by the housing prices. Agents exchange location in order to fit their status to the cost of their housing. On the other hand, the price of a particular house depends on the status of its tenant, and on the neighborhood mean lodging cost weighted by a control parameter. The agent's dynamics converges to a spatially organized configuration, whose regularity is measured by using an entropy-like indicator. This simple model provides a dynamical process organizing the virtual city, in a way that the population inequality and the inflationary parameter determine the degree of residential segregation in the final stage of the process, in agreement with the segregation-inequality thesis put forward by Douglas Massey.
Area and Power Modeling for Networks-on-Chip with Layout Awareness
Authors: Meloni Paolo , Loi Igor , Angiolini Federico , Carta Salvatore , Barbaro Massimo , Raffo Luigi , Benini Luca
Published: May 2007

Networks-on-Chip (NoCs) are emerging as scalable interconnection architectures, designed to support the increasing amount of cores that are integrated onto a silicon die. Compared to traditional interconnects, however, NoCs still lack well established CAD deployment tools to tackle the large amount of available degrees of freedom, starting from the choice of a network topology. “Silicon-aware” optimization tools are now emerging in literature; they select an NoC topology taking into account the tradeoff between performance and hardware cost, that is, area and power consumption. A key requirement for the effectiveness of these tools, however, is the availability of accurate analytical models for power and area. Such models are unfortunately not as available and well understood as those for traditional communication fabrics. Further, simplistic models may turn out to be totally inaccurate when applied to wire dominated architectures; this observation demands at least for a model validation step against placed and routed devices. In this work, given an NoC reference architecture, we present a flow to devise analytical models of area occupation and power consumption of NoC switches, and propose strategies for coefficient characterization which have different tradeoffs in terms of accuracy and of modeling activity effort. The models are parameterized on several architectural, synthesis-related, and traffic variables, resulting in maximum flexibility. We finally assess the accuracy of the models, checking whether they can also be applied to placed and routed NoC blocks.
Semiconductor-Superlattice Parametric Oscillator as a Subterahertz and Possible Terahertz Radiation Source
Authors: Renk Karl F. , Rogl Andreas , Stahl Benjamin I. , Muthmann Matthias , Appel Helmut , Jain Manish , Glukhovskoy Anatoly , Schuh Dieter , Wegscheider Werner
Published: May 2007

We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subterahertz frequency (near 300 GHz). The oscillator is driven by a microwave source (frequency near 100 GHz). We also present an analysis indicating that operation at frequencies above 1 THz should be possible. The SPO is based on the ability of conduction electrons in a superlattice to perform Bloch oscillations. Broadband tunability as well as the monochromacy of a driving microwave field are transferred to the SPO.
On Global Exponential Stability of Discrete-Time Hopfield Neural Networks with Variable Delays
Authors: Zhang Qiang , Wei Xiaopeng , Xu Jin
Published: May 2007

Global exponential stability of a class of discrete-time Hopfield neural networks with variable delays is considered. By making use of a difference inequality, a new global exponential stability result is provided. The result only requires the delay to be bounded. For this reason, the result is milder than those presented in the earlier references. Furthermore, two examples are given to show the efficiency of our result.
The Design of a Chemical Virtual Instrument Based on LabVIEW for Determining Temperatures and Pressures
Authors: Wang Wen-Bin , Li Jang-Yuan , Wu Qi-Jun
Published: May 2007

A LabVIEW-based self-constructed chemical virtual instrument (VI) has been developed for determining temperatures and pressures. It can be put together easily and quickly by selecting hardware modules, such as the PCI-DAQ card or serial port method, different kinds of sensors, signal-conditioning circuits or finished chemical instruments, and software modules such as data acquisition, saving, proceeding. The VI system provides individual and extremely flexible solutions for automatic measurements in physical chemistry research.
Convergence of Weighted Linear Process forρ-Mixing Random Variables
Authors: Cai Guang-Hui
Published: May 2007

A central limit theorem and a functional central limit theorem are obtained for weighted linear process ofρ-mixing sequences for theXt=∑i=0∞aiYt−i, where{Yi,0≤i<∞}is a sequence ofρ-mixing random variables withEYi=0,0<EYi2<∞,∑i=1∞ρ(2i)<∞. The results obtained generalize the results of Liang et al. (2004) toρ-mixing sequences.
Coincidence Theorems, Generalized Variational Inequality Theorems, and Minimax Inequality Theorems for the "Equation missing" -Mapping on "Equation missing" -Convex Spaces
Authors: Chen Chi-Ming , Chang Tong-Huei , Liao Ya-Pei
Published: May 2007

We establish some coincidence theorems, generalized variational inequality theorems, and minimax inequality theorems for the family "Equation missing"-KKM "Equation missing" and the "Equation missing"-mapping on "Equation missing"-convex spaces.
Regulation of Defense Responses against Protozoan Infection by Interleukin-27 and Related Cytokines
Authors: Yoshida Hiroki , Miyazaki Yoshiyuki , Wang Sen , Hamano Shinjiro
Published: May 2007

Cytokine-mediated immunity is crucial in the defense against pathogens. Recently, IL-23 and IL-27 were identified, which along with IL-12 belong to the IL-12 cytokine family. IL-27 is pivotal for the induction of helper T cell (Th) 1 responses while IL-23 is important for the proliferation of memory type Th1 cells. Recent studies revealed that IL-27 also has an anti-inflammatory property. In some protozoan infection, various proinflammatory cytokines were over produced causing lethal inflammatory responses in IL-27 receptor-deficient mice. The anti-inflammatory effect of IL-27 depends, at least partly, on inhibition of the development of Th17 cells, a newly identified Th population that is induced by IL-23 and is characterized by the production of the inflammatogenic cytokine, IL-17. IL-27 thus has a double identity as an initiator and as an attenuator of immune responses and inflammation. With the discoveries of the new IL-12-related cytokines and Th17 cells, Th development is facing a new paradigm.
An Investigation on Gas Lift Performance Curve in an Oil-Producing Well
Authors: Saepudin Deni , Soewono Edy , Sidarto Kuntjoro Adji , Gunawan Agus Yodi , Siregar Septoratno , Sukarno Pudjo
Published: May 2007

The main objective in oil production system using gas lift technique is to obtain the optimum gas injection rate which yields the maximum oil production rate. Relationship between gas injection rate and oil production rate is described by a continuous gas lift performance curve (GLPC). Obtaining the optimum gas injection rate is important because excessive gas injection will reduce production rate, and also increase the operation cost. In this paper, we discuss a mathematical model for gas lift technique and the characteristics of the GLPC for a production well, for which one phase (liquid) is flowing in the reservoir, and two phases (liquid and gas) in the tubing. It is shown that in certain physical condition the GLPC exists and is unique. Numerical computations indicate unimodal properties of the GLPC. It is also constructed here a numerical scheme based on genetic algorithm to compute the optimum oil production.
Rational Probabilistic Deciders—Part II: Collective Behavior
Authors: Kabamba P. T. , Lin W.-C. , Meerkov S. M.
Published: May 2007

This paper explores the behavior of rational probabilistic deciders (RPDs) in three types of collectives: zero sum matrix games, fractional interactions, and Edgeworth exchange economies. The properties of steady states and transients are analyzed as a function of the level of rationality,N, and, in some cases, the size of the collective,M. It is shown that collectives of RPDs, may or may not behave rationally, depending, for instance, on the relationship betweenNandM(under fractional interactions) orNand the minimum amount of product exchange (in Edgeworth economies). The results obtained can be useful for designing rational reconfigurable systems that can autonomously adapt to changing environments.
Bifurcation Analysis for a Two-Dimensional Discrete-Time Hopfield Neural Network with Delays
Authors: Ren Yaping , Li Yongkun
Published: May 2007

A bifurcation analysis is undertaken for a discrete-time Hopfield neural network with four delays. Conditions ensuring the asymptotic stability of the null solution are obtained with respect to two parameters of the system. Using techniques developed by Kuznetsov to a discrete-time system, we study the Neimark-Sacker bifurcation (also called Hopf bifurcation for maps) of the system. The direction and the stability of the Neimark-Sacker bifurcation are investigated by applying the normal form theory and the center manifold theorem.
Stem Cell Fate Analysis Revisited: Interpretation of Individual Clone Dynamics in the Light of a New Paradigm of Stem Cell Organization
Authors: Roeder Ingo , Braesel Katrin , Lorenz Ronny , Loeffler Markus
Published: May 2007

Many experimental findings on heterogeneity, flexibility, and plasticity of tissue stem cells are currently challenging stem cell concepts that assume a cell intrinsically predefined, unidirectional differentiation program. In contrast to these classical concepts, nonhierarchical self-organizing systems provide an elegant and comprehensive alternative to explain the experimental data. Here we present the application of such a self-organizing concept to quantitatively describe the hematopoietic stem cell system. Focusing on the analysis of individual-stem-cell fates and clonal dynamics, we particularly discuss implications of the theoretical results on the interpretation of experimental findings. We demonstrate that it is possible to understand hematopoietic stem cell organization without assumptions on unidirectional developmental hierarchies, preprogrammed asymmetric division events or other assumptions implying the existence of a predetermined stem cell entity. The proposed perspective, therefore, changes the general paradigm of thinking about stem cells.
The Mathematical Foundations of 3D Compton Scatter Emission Imaging
Authors: Truong T. T. , Nguyen M. K. , Zaidi H.
Published: May 2007

The mathematical principles of tomographic imaging using detected (unscattered) X‐ or gamma‐rays are based on the two‐dimensional Radon transform and many of its variants. In this paper, we show that two new generalizations, called conical Radon transforms, are related to three‐dimensional imaging processes based on detected Compton scattered radiation. The first class of conical Radon transform has been introduced recently to support imaging principles of collimated detector systems. The second class is new and is closely related to the Compton camera imaging principles and invertible under special conditions. As they are poised to play a major role in future designs of biomedical imaging systems, we present an account of their most important properties which may be relevant for active researchers in the field.
Photonic Crystal Waveguide Weakly Interacting with Multiple Off-Channel Resonant Features Formed of Kerr Nonlinear Dielectric Media
Authors: McGurn A. R.
Published: May 2007

A theoretical study is presented of guided modes of a photonic crystal waveguide for cases in which they interact with multiple bound electromagnetic modes localized on off-channel impurity features of Kerr nonlinear media. The interest is on
the properties of resonant scattering and optical bistability exhibited by the system and the coherent scattering of the guided modes due to their simultaneous resonant interactions with multiple bound modes. In first study, two off-channel features on opposite sides of a photonic crystal waveguide are made of different Kerr nonlinear dielectric media. In second study, an off-channel feature is composed of two neighboring sites having different Kerr dielectric properties. In addition to numerical results
a number of analytical results are presented providing simple explanations of the quantitative behaviors of the systems. A relationship of these systems to forms of electromagnetic-induced transparency and modifications of waveguide dispersion relations is discussed.
Modeling of Coupled Roll and Yaw Damping of a Floating Body in Waves
Authors: Das S. K. , Das S. N.
Published: May 2007

A mathematical model is described to investigate the damping moment of weakly nonlinear roll and yaw motions of a floating body in time domain under the action of sinusoidal waves. The mathematical formulation for added mass moment of inertia and damping is presented by approximating time-dependent coefficients and forcing moments when small distortion holds. Using perturbation technique, we obtain orderwise equations wherein the closed-form solution is obtained for zeroth-order case, and for higher-order cases we resort to numerical integration using Runge-Kutta method with adaptive step-size algorithm. In order to analyze the model result, we perform numerical experiment for a vessel of 19190 tons under the beam wave of 1 m height and frequency 0.74 rad/s. Closer inspection in damping analysis reveals that viscous effect becomes significant for roll damping; whereas for yaw damping, contribution from added mass variation becomes significant.
EGFR Activation and Ultraviolet Light‐Induced Skin Carcinogenesis
Authors: El-Abaseri Taghrid B. , Hansen Laura A.
Published: May 2007

The epidermal growth factor receptor (EGFR) regulates the proliferation of keratinocytes through multiple mechanisms that differ depending on the localization of the cell within the skin. Ultraviolet (UV) irradiation, the main etiologic factor in the development of skin cancer, also activates the receptor. In this review, we discuss how the UV-induced activation of EGFR regulates the response of the skin to UV. UV-induced EGFR activation increases keratinocyte proliferation, suppresses apoptosis, and augments and accelerates epidermal hyperplasia in response to UV. Pharmacological inhibition of the UV-induced activation of EGFR in a genetically initiated mouse skin tumorigenesis model suppresses tumorigenesis and the activation of mitogen-activated protein (MAP) kinases and phosphatidyl inositol-3-kinase (PI3K)/AKT signaling pathways. EGFR has pleiotropic, complex, and cell-type-specific functions in cutaneous keratinocytes; suggesting that the receptor is an appropriate target for the development of molecularly targeted therapies for skin cancer and other pathologies.
Numerical Exploration of Kaldorian Macrodynamics: Hopf-Neimark Bifurcations and Business Cycles with Fixed Exchange Rates
Authors: Asada Toichiro , Douskos Christos , Markellos Panagiotis
Published: May 2007

We explore numerically a three-dimensional discrete-time Kaldorian macrodynamic model in an open economy with fixed exchange rates, focusing on the effects of variation of the model parameters, the speed of adjustment of the goods marketα, and the degree of capital mobilityβon the stability of equilibrium and on the existence of business cycles. We determine the stability region in the parameter space and find that increase ofαdestabilizes the equilibrium more quickly than increase ofβ. We determine the Hopf-Neimark bifurcation curve along which business cycles are generated, and discuss briefly the occurrence of Arnold tongues. Bifurcation and Lyapunov exponent diagrams are computed providing information on the emergence, persistence, and amplitude of the cycles and illustrating the complex dynamics involved. Examples of cycles and other attractors are presented. Finally, we discuss a two-dimensional variation of the model related to a “wealth effect,” called model 2, and show that in this case,αdoes not destabilize the equilibrium more quickly thanβ, and that a Hopf-Neimark bifurcation curve does not exist in the parameter space, therefore model 2 does not produce cycles.
Ubiquitin and Ubiquitin-Like Proteins in Protein Regulation
Authors: Herrmann Joerg , Lerman Lilach O. , Lerman Amir
Published: May 2007

The discovery of the ubiquitin system was awarded with the Nobel Prize in Chemistry in 2004. Labeling of intracellular proteins for degradation by a multienzymatic complex, called the proteasome, was identified as the main function of this system. Subsequently, it was discovered that the attachment of ubiquitin to proteins can modify their function without degradation. Finally, a number of other molecules were recognized to be conjugated to proteins in a manner similar to ubiquitin and were henceforth called ubiquitin-like proteins. This review provides an overview of this class of molecules and its implication for function, subcellular location, and half-life of proteins.