bluuebunny/crossref_metadata_2025 huggingface dataset:
ON A CLASS OF SINGULAR NONLINEAR TRAVELING WAVE EQUATIONS
Authors: LI JIBIN , CHEN GUANRONG
Published: February 2008

The existence of solitary wave, kink wave and periodic wave solutions of a class of singular reaction–diffusion equations is obtained using some effective methods from the dynamical systems theory. Specially, for a class of nonlinear wave equations, fundamental properties of profiles of traveling wave solutions determined by some bounded orbits of the traveling wave systems are rigorously proved. Parametric conditions that guarantee the existence of the aforementioned solutions are derived and given explicitly.
FRACTAL AND WADA EXIT BASIN BOUNDARIES IN TOKAMAKS
Authors: PORTELA JEFFERSON S. E. , CALDAS IBERÊ L. , VIANA RICARDO L. , SANJUÁN MIGUEL A. F.
Published: February 2008

The creation of an outer layer of chaotic magnetic field lines in a tokamak is useful to control plasma-wall interactions. Chaotic field lines (in the Lagrangian sense) in this region eventually hit the tokamak wall and are considered lost. Due to the underlying dynamical structure of this chaotic region, namely a chaotic saddle formed by intersections of invariant stable and unstable manifolds, the exit patterns are far from being uniform, rather presenting an involved fractal structure. If three or more exit basins are considered, the respective basins exhibit an even stronger Wada property, for which a boundary point is arbitrarily close to points belonging to all exit basins. We describe such a structure for a tokamak with an ergodic limiter by means of an analytical Poincaré field line mapping.
A NONLINEAR DYNAMICS PERSPECTIVE OF WOLFRAM'S NEW KIND OF SCIENCE PART VIII: MORE ISLES OF EDEN
Authors: CHUA LEON O. , KARACS KRISTOF , SBITNEV VALERY I. , GUAN JUNBIAO , SHIN JINWOOK
Published: February 2008

This paper presents the basin tree diagrams of all hyper Bernoulli στ-shift rules for string lengths L = 3, 4, …, 8. These diagrams have revealed many global and time-asymptotic properties that we have subsequently proved to be true for all L < ∞. In particular, we have proved that local rule [Formula: see text] has no Isles of Eden for all L, and that local rules [Formula: see text] and [Formula: see text] are inhabited by a dense set (continuum) of Isles of Eden if, and only if, L is an odd integer. A novel and powerful graph-theoretic tool, called Isles-of-Eden digraph, has been developed and can be used to test the existence of dense Isles of Eden of any local rule which satisfies certain constraints, such as rules [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], as well as all invariant local rules, such as rules [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], subject to no constraints.
Cerebellum-Like Structures and Their Implications for Cerebellar Function
Authors: Bell Curtis C. , Han Victor , Sawtell Nathaniel B.
Published: February 2008

The nervous systems of most vertebrates include both the cerebellum and structures that are architecturally similar to the cerebellum. The cerebellum-like structures are sensory structures that receive input from the periphery in their deep layers and parallel fiber input in their molecular layers. This review describes these cerebellum-like structures and compares them with the cerebellum itself. The cerebellum-like structures in three groups of fish act as adaptive sensory processors in which the signals conveyed by parallel fibers in the molecular layer predict the patterns of sensory input to the deep layers through a process of associative synaptic plasticity. Similarities between the cerebellum-like structures and the cerebellum suggest that the cerebellum may also generate predictions about expected sensory inputs or states of the system, as suggested also by clinical, experimental, and theoretical studies of the cerebellum. Understanding the process of predicting sensory patterns in cerebellum-like structures may therefore be a source of insight into cerebellar function.
Effects of osmotic stress on the activity of MAPKs and PDGFR-β-mediated signal transduction in NIH-3T3 fibroblasts
Authors: Nielsen M.-B. , Christensen S. T. , Hoffmann E. K.
Published: February 2008

Signaling in cell proliferation, cell migration, and apoptosis is highly affected by osmotic stress and changes in cell volume, although the mechanisms underlying the significance of cell volume as a signal in cell growth and death are poorly understood. In this study, we used NIH-3T3 fibroblasts in a serum- and nutrient-free inorganic medium (300 mosM) to analyze the effects of osmotic stress on MAPK activity and PDGF receptor (PDGFR)-β-mediated signal transduction. We found that hypoosmolarity (cell swelling at 211 mosM) induced the phosphorylation and nuclear translocation of ERK1/2, most likely via a pathway independent of PDGFR-β and MEK1/2. Conversely, hyperosmolarity (cell shrinkage at 582 mosM) moved nuclear and phosphorylated ERK1/2 to the cytoplasm and induced the phosphorylation and nuclear translocation of p38 and phosphorylation of JNK1/2. In a series of parallel experiments, hypoosmolarity did not affect PDGF-BB-induced activation of PDGFR-β, whereas hyperosmolarity strongly inhibited ligand-dependent PDGFR-β activation as well as downstream mitogenic signal components of the receptor, including Akt and the MEK1/2-ERK1/2 pathway. Based on these results, we conclude that ligand-dependent activation of PDGFR-β and its downstream effectors Akt, MEK1/2, and ERK1/2 is strongly modulated (inhibited) by hyperosmotic cell shrinkage, whereas cell swelling does not seem to affect the activation of the receptor but rather to activate ERK1/2 via a different mechanism. It is thus likely that cell swelling via activation of ERK1/2 and cell shrinkage via activation of the p38 and JNK pathway and inhibition of the PDGFR signaling pathway may act as key players in the regulation of tissue homeostasis.
Natriuretic peptides stimulate the cardiac sodium pump via NPR-C-coupled NOS activation
Authors: William M. , Hamilton E. J. , Garcia A. , Bundgaard H. , Chia K. K. M. , Figtree G. A. , Rasmussen H. H.
Published: February 2008

Natriuretic peptides (NPs) and their receptors (NPRs) are expressed in the heart, but their effects on myocyte function are poorly understood. Because NPRs are coupled to synthesis of cGMP, an activator of the sarcolemmal Na+-K+ pump, we examined whether atrial natriuretic peptide (ANP) regulates the pump. We voltage clamped rabbit ventricular myocytes and identified electrogenic Na+-K+ pump current (arising from the 3:2 Na+:K+ exchange and normalized for membrane capacitance) as the shift in membrane current induced by 100 μmol/l ouabain. Ten nanomoles per liter ANP stimulated the Na+-K+ pump when the intracellular compartment was perfused with pipette solutions containing 10 mmol/l Na+ but had no effect when the pump was at near maximal activation with 80 mmol/l Na+ in the pipette solution. Stimulation was abolished by inhibition of cGMP-activated protein kinase with KT-5823, nitric oxide (NO)-activated guanylyl cyclase with 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ), or NO synthase with NG-nitro-l-arginine methyl ester (l-NAME). Since synthesis of cGMP by NPR-A and NPR-B is not NO dependent or ODQ sensitive, we exposed myocytes to AP-811, a highly selective ligand for the NPR-C “clearance” receptor. It abolished ANP-induced pump stimulation. Conversely, the selective NPR-C agonist ANP(4-23) reproduced stimulation. The stimulation was blocked by l-NAME. To examine NO production in response to ANP(4-23), we loaded myocytes with the NO-sensitive fluorescent dye diacetylated diaminofluorescein-2 and examined them by confocal microscopy. ANP(4-23) induced a significant increase in fluorescence, which was abolished by l-NAME. We conclude that NPs stimulate the Na+-K+ pump via an NPR-C and NO-dependent pathway.
FOXO transcription factors are mechanosensitive and their regulation is altered with aging in the respiratory pump
Authors: Pardo Patricia S. , Lopez Michael A. , Boriek Aladin M.
Published: February 2008

The mechanical regulation of the forkhead box O (FOXO) subclass of transcription factors in the respiratory pump and its implication in aging are completely unknown. We investigated the effects of diaphragm stretch on three FOXO isoforms, Foxo1, Foxo3a, and Foxo4, in normal mice at different ages. We tested the hypotheses that 1) FOXO activities are regulated in response to diaphragm stretch and 2) mechanical properties of aging diaphragm are altered, leading to altered regulation of FOXO with aging. Our results showed that stretch downregulated FOXO DNA-binding activity by a mechanism that required Akt and IKK activation in young mice but that these pathways lost their mechanosensitivity with age. This aberrant regulation of FOXO with aging was associated with altered viscoelasticity, compliance, and extensibility of the aged diaphragm. Curiously, the dramatic decrease of the nuclear content of Foxo1 and Foxo3a, the two isoforms associated with muscle atrophy, with aging correlated with higher basal activation of Akt and IKK signaling in diaphragms of old mice. In contrast, the stability of Foxo4 in the nucleus became dependent on JNK, which is strongly activated in aged diaphragm. This finding suggests that Foxo4 was responsible for the FOXO-dependent transcriptional activity in aging diaphragm. Our data support the hypothesis that aging alters the mechanical properties of the respiratory pump, leading to altered mechanical regulation of the stretch-induced signaling pathways controlling FOXO activities. Our study supports a mechanosensitive signaling mechanism that is responsible for regulation of the FOXO transcription factors by aging.
Nitric oxide facilitates NFAT-dependent transcription in mouse myotubes
Authors: Drenning Jason A. , Lira Vitor A. , Simmons Catherine G. , Soltow Quinlyn A. , Sellman Jeff E. , Criswell David S.
Published: February 2008

Intracellular calcium transients in skeletal muscle cells initiate phenotypic adaptations via activation of calcineurin and its effector nuclear factor of activated t-cells (NFAT). Furthermore, endogenous production of nitric oxide (NO) via calcium-calmodulin-dependent NO synthase (NOS) is involved in skeletal muscle phenotypic plasticity. Here, we provide evidence that NO enhances calcium-dependent nuclear accumulation and transcriptional activity of NFAT and induces phosphorylation of glycogen synthase kinase-3β (GSK-3β) in C2C12 myotubes. The calcium ionophore A23187 (1 μM for 9 h) or thapsigargin (2 μM for 4 h) increased NFAT transcriptional activity by seven- and fourfold, respectively, in myotubes transiently transfected with an NFAT-dependent reporter plasmid (pNFAT-luc, Stratagene). Cotreatment with the NOS-inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 5 mM) or the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM) prevented the calcium effects on NFAT activity. The NO donor diethylenetriamine-NONO (DETA-NO; 10 μM) augmented the effects of A23187 on NFAT-dependent transcription. Similarly, A23187 (0.4 μM for 4 h) caused nuclear accumulation of NFAT and increased phosphorylation (i.e., inactivation) of GSK-3β, whereas cotreatment with l-NAME or ODQ inhibited these responses. Finally, the NO donor 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPA-NO; 1 μM for 1 h) increased phosphorylation of GSK-3β in a manner dependent on guanylate cyclase activity. We conclude that NOS activity mediates calcium-induced phosphorylation of GSK-3β and activation of NFAT-dependent transcription in myotubes. Furthermore, these effects of NO are guanylate cyclase-dependent.
Development and Physiological Regulation of Intestinal Lipid Absorption. III. Intestinal transporters and cholesterol absorption
Authors: Hui David Y. , Labonté Eric D. , Howles Philip N.
Published: February 2008

Intestinal cholesterol absorption is modulated by transport proteins in enterocytes. Cholesterol uptake from intestinal lumen requires several proteins on apical brush-border membranes, including Niemann-Pick C1-like 1 (NPC1L1), scavenger receptor B-I, and CD36, whereas two ATP-binding cassette half transporters, ABCG5 and ABCG8, on apical membranes work together for cholesterol efflux back to the intestinal lumen to limit cholesterol absorption. NPC1L1 is essential for cholesterol absorption, but its function as a cell surface transporter or an intracellular cholesterol transport protein needs clarification. Another ATP transporter, ABCA1, is present in the basolateral membrane to mediate HDL secretion from enterocytes.
Placental restriction of fetal growth decreases IGF1 and leptin mRNA expression in the perirenal adipose tissue of late gestation fetal sheep
Authors: Duffield Jaime A. , Vuocolo Tony , Tellam Ross , Yuen Bernard S. , Muhlhausler Beverly S. , McMillen I. Caroline
Published: February 2008

Placental restriction (PR) of fetal growth results in a low birth weight and an increased visceral fat mass in postnatal life. We investigated whether PR alters expression of genes that regulate adipogenesis [IGF1, IGF1 receptor (IGF1R), IGF2, IGF2R, proliferator-activated receptor-γ, retinoid-X-receptor-α], adipocyte metabolism (lipoprotein lipase, G3PDH, GAPDH) and adipokine signaling (leptin, adiponectin) in visceral adipose tissue before birth. PR was induced by removal of the majority of endometrial caruncles in nonpregnant ewes before mating. Fetal blood samples were collected from 116 days gestation, and perirenal visceral adipose tissue (PAT) was collected from PR and control fetuses at 145 days. PAT gene expression was measured by quantitative RT-PCR. PR fetuses had a lower weight (PR 2.90 ± 0.32 kg; control, 5.12 ± 0.24 kg; P < 0.0001), mean gestational arterial Po2( P < 0.0001), plasma glucose ( P < 0.01), and insulin concentrations ( P < 0.02), than controls. The expression of IGF1 mRNA in PAT was lower in the PR fetuses (PR, 0.332 ± 0.063; control, 0.741 ± 0.083; P < 0.01). Leptin mRNA expression in PAT was also lower in PR fetuses (PR, 0.077 ± 0.009; control, 0.115 ± 0.013; P < 0.05), although there was no difference in the expression of other adipokine or adipogenic genes in PAT between PR and control fetuses. Thus, restriction of placental and hence, fetal substrate supply results in decreased IGF1 and leptin expression in fetal visceral adipose tissue, which may alter the functional development of the perirenal fat depot and contribute to altered leptin signaling in the growth-restricted newborn and the subsequent emergence of an increased visceral adiposity.
Cadmium-dependent oxygen limitation affects temperature tolerance in eastern oysters (Crassostrea virginicaGmelin)
Authors: Lannig Gisela , Cherkasov Anton S. , Pörtner Hans-O. , Bock Christian , Sokolova Inna M.
Published: February 2008

Marine ectotherms, including oysters are exposed to variable environmental conditions in coastal shallow waters and estuaries. In the light of global climate change, additional stressors like pollution might pose higher risk to populations. On the basis of the concept of oxygen- and capacity-limited thermal tolerance in aquatic ectotherms ( 40 ), we show that a persistent pollutant, cadmium, can have detrimental effects on oysters ( Crassostrea virginica). During acute warming from 20 to 28°C (4°C/48 h) standard metabolic rate (SMR) rose in control and cadmium-exposed (50 μg Cd2+/l) animals, with a consistently higher SMR in Cd-exposed oysters. Additionally, Cd-exposed oysters showed a stronger temperature-dependent decrease in hemolymph oxygen partial pressures. This observation indicates that the effect of temperature on aerobic metabolism was exacerbated due to the additional Cd stress. The oxygen delivery systems could not provide enough oxygen to cover Cd-induced elevated metabolic demands at high temperatures. Interestingly, cardiac performance (measured as the heart rate and hemolymph supply to tissues) rose to a similar extent in control and Cd-exposed oysters with warming indicating that cardiac output was unable to compensate for elevated energy demand in Cd-exposed oysters. Together with the literature data on metal-induced reduction of ventilatory capacity, these findings suggest that synergistic effects of elevated temperatures and cadmium exposure led to oxygen limitation by impaired performance in oxygen supply through ventilation and circulation. Overall, cadmium exposure resulted in progressive hypoxemia in oysters at high temperatures, suggesting that the thermal tolerance window is narrowed in marine ectotherms inhabiting polluted areas compared with pristine environments.
Circadian rhythm disorganization produces profound cardiovascular and renal disease in hamsters
Authors: Martino Tami A. , Oudit Gavin Y. , Herzenberg Andrew M. , Tata Nazneen , Koletar Margaret M. , Kabir Golam M. , Belsham Denise D. , Backx Peter H. , Ralph Martin R. , Sole Michael J.
Published: February 2008

Sleep deprivation, shift work, and jet lag all disrupt normal biological rhythms and have major impacts on health; however, circadian disorganization has never been shown as a causal risk factor in organ disease. We now demonstrate devastating effects of rhythm disorganization on cardiovascular and renal integrity and that interventions based on circadian principles prevent disease pathology caused by a short-period mutation ( tau) of the circadian system in hamsters. The point mutation in the circadian regulatory gene, casein kinase-1ε, produces early onset circadian entrainment with fragmented patterns of behavior in +/ tau heterozygotes. Animals die at a younger age with cardiomyopathy, extensive fibrosis, and severely impaired contractility; they also have severe renal disease with proteinuria, tubular dilation, and cellular apoptosis. On light cycles appropriate for their genotype (22 h), cyclic behavioral patterns are normalized, cardiorenal phenotype is reversed, and hearts and kidneys show normal structure and function. Moreover, hypertrophy does not develop in animals whose suprachiasmatic nucleus was ablated as young adults. Circadian organization therefore is critical for normal health and longevity, whereas chronic global asynchrony is implicated in the etiology of cardiac and renal disease.
Heterogeneity of muscarinic receptor-mediated Ca2+responses in cultured urothelial cells from rat
Authors: Kullmann F. Aura , Artim D. , Beckel J. , Barrick S. , de Groat W. C. , Birder L. A.
Published: February 2008

Muscarinic receptors (mAChRs) have been identified in the urothelium, a tissue that may be involved in bladder sensory mechanisms. This study investigates the expression and function of mAChRs using cultured urothelial cells from the rat. RT-PCR established the expression of all five mAChR subtypes. Muscarinic agonists acetylcholine (ACh; 10 μM), muscarine (Musc; 20 μM), and oxotremorine methiodide (OxoM; 0.001–20 μM) elicited transient repeatable increases in the intracellular calcium concentration ([Ca2+]i) in ∼50% of cells. These effects were blocked by the mAChR antagonist atropine methyl nitrate (10 μM). The sources of [Ca2+]ichanges included influx from external milieu in 63% of cells and influx from external milieu plus release from internal stores in 27% of cells. The use of specific agonists and antagonists (10 μM M1agonist McN-A-343; 10 μM M2, M3antagonists AF-DX 116, 4-DAMP) revealed that M1, M2, M3subtypes were involved in [Ca2+]ichanges. The PLC inhibitor U-73122 (10 μM) abolished OxoM-elicited Ca2+responses in the presence of the M2antagonist AF-DX 116, suggesting that M1, M3, or M5mediates [Ca2+]iincreases via PLC pathway. ACh (0.1 μM), Musc (10 μM), oxotremorine sesquifumarate (20 μM), and McN-A-343 (1 μM) acting on M1, M2, and M3mAChR subtypes stimulated ATP release from cultured urothelial cells. In summary, cultured urothelial cells express functional M1, M2, and M3mAChR subtypes whose activation results in ATP release, possibly through mechanisms involving [Ca2+]ichanges.
Angiopoietin 1 and 2 gene and protein expression is differentially regulated in acute anti-Thy1.1 glomerulonephritis
Authors: Câmpean Valentina , Karpe Britta , Haas Christian , Atalla Akram , Peters Harm , Rupprecht Harald , Liebner Stefan , Acker Till , Plate Karl , Amann Kerstin
Published: February 2008

Capillary neoformation is important in repair of glomerular injury of various origins. VEGF was shown to be crucial for glomerular capillary repair in glomerulonephritis (GN). We reasoned that other angiogenic factors are likewise involved in glomerular capillary remodeling and found angiopoietin 1 and -2 (ANG1 and ANG2) mRNA to be upregulated in cDNA microarrays of microdissected glomeruli of anti-Thy1.1 GN of the rat. We then studied glomerular in situ gene and protein expression of ANG1 and ANG2 and their receptor Tie-2 in the course of anti-Thy1.1 GN, which was induced by injection of OX-7 antibody. Animals were perfusion fixed at days 6 and 12 after GN induction and compared with nonnephritic controls receiving PBS. Capillary damage and repair were quantitatively analyzed using stereological techniques. Gene and protein expression of ANG1 and ANG2 and their receptor Tie-2 was analyzed using real-time quantitative PCR from microdissected glomeruli, nonradioactive in situ hybridization, double immunofluorescence, and Western blot analysis. Glomerular capillarization assessed as length density was significantly lower at day 6 of anti-Thy1.1 GN than in controls; it was back to normal values at day 12. ANG1 and ANG2 gene expression was markedly upregulated at day 6 of the disease compared with controls. Protein expression of ANG1 and ANG2 was confined to podocytes and that of Tie-2 to endothelial cells. At day 12 of anti-Thy1.1 GN when capillary restoration was nearly completed, ANG1 and ANG2 gene expression returned to basal levels, whereas Tie-2 expression was still high. With the use of a combined molecular and in situ approach, the spatial and temporal gene and protein expression of the angiopoietins and their receptor was analyzed in anti-Thy1.1 GN. The results indicate that glomerular expression of ANG1 and ANG2 and Tie-2 is differentially regulated and may contribute to healing and endothelial cell stabilization in experimental GN.
Molecular mechanism of ADP-ribosyl cyclase activation in angiotensin II signaling in murine mesangial cells
Authors: Kim Seon-Young , Gul Rukhsana , Rah So-Young , Kim Suhn Hee , Park Sung Kwang , Im Mie-Jae , Kwon Ho Jeong , Kim Uh-Hyun
Published: February 2008

ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca2+-mobilizing second messenger cyclic ADP-ribose (cADPR) from NAD+. In this study, we investigated the molecular basis of ADPR-cyclase activation and the following cellular events in angiotensin II (ANG II) signaling in mouse mesangial cells (MMCs). Treatment of MMCs with ANG II induced an increase in intracellular Ca2+concentrations through a transient Ca2+release via an inositol 1,4,5-trisphosphate receptor and a sustained Ca2+influx via L-type Ca2+channels. The sustained Ca2+signal, but not the transient Ca2+signal, was blocked by a cADPR antagonistic analog, 8-bromo-cADPR (8-Br-cADPR), and an ADPR-cyclase inhibitor, 4,4′-dihydroxyazobenzene (DHAB). In support of the results, ANG II stimulated cADPR production in a time-dependent manner, and DHAB inhibited ANG II-induced cADPR production. Application of pharmacological inhibitors revealed that activation of ADPR-cyclase by ANG II involved ANG II type 1 receptor, phosphoinositide 3-kinase, protein tyrosine kinase, and phospolipase C-γ1. Moreover, DHAB as well as 8-Br-cADPR abrogated ANG II-mediated Akt phosphorylation, nuclear translocation of nuclear factor of activated T cell, and uptake of [3H]thymidine and [3H]leucine in MMCs. These results demonstrate that ADPR-cyclase in MMCs plays a pivotal role in ANG II signaling for cell proliferation and protein synthesis.
Organization and Properties of GABAergic Neurons in Solitary Tract Nucleus (NTS)
Authors: Bailey Timothy W. , Appleyard Suzanne M. , Jin Young-Ho , Andresen Michael C.
Published: February 2008

Cranial visceral afferents enter the brain at the solitary tract nucleus (NTS). GABAergic neurons are scattered throughout the NTS, but their relation to solitary tract (ST) afferent pathways is imprecisely known. We hypothesized that most GABAergic NTS neurons would be connected only indirectly to the ST. We identified GABAergic neurons in brain stem horizontal slices using transgenic mice in which enhanced green fluorescent protein (EGFP) expression was linked to glutamic acid decarboxylase expression (GAD+). Finely graded electrical shocks to ST recruit ST-synchronized synaptic events with all-or-none thresholds and individual waveforms did not change with greater suprathreshold intensities—evidence consistent with initiation by single afferent axons. Most (∼70%) GAD+ neurons received ST-evoked excitatory postsynaptic currents (EPSCs) that had minimally variant latencies (jitter, SD of latency <200 μs) and waveforms consistent with single, direct ST connections (i.e., monosynaptic). Increasing stimulus intensity evoked additional ST-synchronized synaptic responses with jitters >200 μs including inhibitory postsynaptic currents (IPSCs), indicating indirect connections (polysynaptic). Shocks of suprathreshold intensity delivered adjacent (50–300 μm) to the ST failed to excite non-ST inputs to second-order neurons, suggesting a paucity of axons passing near to ST that connected to these neurons. Despite expectations, we found similar ST synaptic patterns in GAD+ and unlabeled neurons. Generally, ST information that arrived indirectly had small amplitudes (EPSCs and IPSCs) and frequency-dependent failures that reached >50% for IPSCs to bursts of stimuli. This ST afferent pathway organization is strongly use-dependent—a property that may tune signal propagation within and beyond NTS.
Responses of Auditory Cortex to Complex Stimuli: Functional Organization Revealed Using Intrinsic Optical Signals
Authors: Nelken Israel , Bizley Jennifer K. , Nodal Fernando R. , Ahmed Bashir , King Andrew J. , Schnupp Jan W. H.
Published: February 2008

We used optical imaging of intrinsic signals to study the large-scale organization of ferret auditory cortex in response to complex sounds. Cortical responses were collected during continuous stimulation by sequences of sounds with varying frequency, period, or interaural level differences. We used a set of stimuli that differ in spectral structure, but have the same periodicity and therefore evoke the same pitch percept (click trains, sinusoidally amplitude modulated tones, and iterated ripple noise). These stimuli failed to reveal a consistent periodotopic map across the auditory fields imaged. Rather, gradients of period sensitivity differed for the different types of periodic stimuli. Binaural interactions were studied both with single contralateral, ipsilateral, and diotic broadband noise bursts and with sequences of broadband noise bursts with varying level presented contralaterally, ipsilaterally, or in opposite phase to both ears. Contralateral responses were generally largest and ipsilateral responses were smallest when using single noise bursts, but the extent of the activated area was large and comparable in all three aural configurations. Modulating the amplitude in counter phase to the two ears generally produced weaker modulation of the optical signals than the modulation produced by the monaural stimuli. These results suggest that binaural interactions seen in cortex are most likely predominantly due to subcortical processing. Thus our optical imaging data do not support the theory that the primary or nonprimary cortical fields imaged are topographically organized to form consistent maps of systematically varying sensitivity either to stimulus pitch or to simple binaural properties of the acoustic stimuli.
Hyperthermic Preconditioning of Presynaptic Calcium Regulation inDrosophila
Authors: Klose M. K. , Atwood H. L. , Robertson R. M.
Published: February 2008

We examined the thermosensitivity of calcium regulation in Drosophila larval neuromuscular junctions, testing effects of prior heat shock and Hsp70 expression. Motor neurons were loaded with either the ratiometric indicator Fura-dextran or the nonratiometric indicator Oregon Green bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid to monitor parameters of calcium regulation as temperature increased. Nerve terminals treated to a prior heat shock, and those of transgenic flies expressing higher than normal levels of Hsp70, were better able to maintain near-normal resting calcium concentrations, calcium influx, and calcium clearance at higher temperatures. Synaptic transmission was also protected by prior heat shock and by higher than normal Hsp70 expression. Thus the thermal limit of synaptic transmission may be directly linked to the stability of calcium regulation.
Fast Locomotor Burst Generation in Late Stage Embryonic Motility
Authors: Bradley Nina S. , Ryu Young U. , Lin John
Published: February 2008

We examined muscle burst patterns and burst frequencies for a distinct form of repetitive leg movement recently identified in chick embryos at embryonic day (E)18 that had not been previously studied. The aim was to determine if burst frequencies during repetitive leg movements were indicative of a rhythm burst generator and if maturing muscle afferent mechanisms could modulate the rhythm. Electromyographic recordings synchronized with video were performed in ovo during spontaneous movement at E15, E18, and E20. Multiple leg muscles were rhythmically active during repetitive leg movements at E18 and E20. Rhythmic activity was present at E15 but less well formed. The ankle dorsi flexor, tibialis anterior, was the most reliably rhythmic muscle because extensor muscles frequently dropped out. Tibialis anterior burst frequencies ranged from 1 to 12 Hz, similar to frequencies during fast locomotor burst generation in lamprey. The distribution in burst frequencies at E18 was greatest at lower frequencies and similar to locomotor data in hatchlings. Relative distributions were more variable at E20 and shifted toward faster frequencies. The shell wall anterior to the leg was removed in some experiments to determine if environmental constraints associated with growth contributed to frequency distributions. Wall removal had minimal impact at E18. E20 embryos extended their foot outside the egg, during which faster frequencies were observed. Our findings provide evidence that embryonic motility in chick may be controlled by a fast locomotor burst generator by E15 and that modulation by proprioceptors may emerge between E18 and E20.
Sensitivity Limitations for Multivariable Linear Filtering
Authors: Weller Steven R.
Published: February 2008

This paper examines fundamental limitations in performance which apply to linear filtering problems associated with multivariable systems having as many inputs as outputs. The results of this paper quantify unavoidable limitations in the sensitivity of state estimates to process and measurement disturbances, as represented by the maximum singular values of the relevant transfer matrices. These limitations result from interpolation constraints imposed by open right half-plane poles and zeros in the transfer matrices linking process noise and output noise with state estimates. Using the Poisson integral inequality, this paper shows how sensitivity limitations and tradeoffs in multivariable filtering problems are intimately related to the directionality properties of the open right half-plane poles and zeros in these transfer matrices.
Design Two-Dimensional IIR Filters Based on Clonal Selection Algorithm with Singular Value Decomposition
Authors: Su Te-Jen , Yang Tsang-Chi , Tsai Wen-Pin , Liu Jia-Wei
Published: February 2008

In this letter, clonal selection algorithm (CSA) with singular value decomposition (SVD) method is investigated for the realization of two-dimentional (2D) infinite-impulse response (IIR) filters with arbitrary magnitude responses. The CSA is applied to optimize the sampled frequencies of transition band of digital filters, then producing a planar response matrix of a 2D IIR digital filter. By using the SVD, 2D magnitude specifications can be decomposed into a pair of 1D filters, and thus the problem of designing a 2D digital filter can be reduced to the one of designing a pair of 1D digital filters or even only one 1D digital filter. The stimulation results show the proposed method has the better performance of the minimum attenuation between the passband and stopband.
Femtosecond Transient Absorption Studies in Cadmium Selenide Nanocrystal Thin Films Prepared by Chemical Bath Deposition Method
Authors: Rath M. C. , Mondal J. A. , Palit D. K. , Mukherjee T. , Ghosh H. N.
Published: February 2008

Dynamics of photo-excited carrier relaxation processes in cadmium selenide nanocrystal thin films prepared by chemical bath deposition method have been studied by nondegenerate femtosecond transient pump-probe spectroscopy. The carriers were generated by exciting at 400 nm laser light and monitored by several other wavelengths. The induced absorption followed by a fast bleach recovery observed near and above the bandgap indicates that the photo-excited carriers (electrons) are first trapped by the available traps and then the trapped electrons absorb the probe light to show a delayed absorption process. The transient decay kinetics was found to be multiexponential in nature. The short time constant,<1 picosecond, was attributed to the trapping of electrons by the surface and/or deep traps and the long time constant,≥20 picoseconds, was due to the recombination of the trapped carriers. A very little difference in the relaxation processes was observed in the samples prepared at bath temperatures from25∘Cto60∘C.
Antimicrobial Study of Newly Synthesized Lanthanide(III) Complexes of 2‐[2‐hydroxy‐3‐methoxyphenyl]‐3‐[2‐hydroxy‐3‐methoxybenzylamino]‐1,2‐dihydroquinazolin‐4(3H)‐one
Authors: Gudasi Kalagouda B. , Havanur Vidyadhar C. , Patil Siddappa A. , Patil Basavaraj R.
Published: February 2008

New lanthanide(III) complexes with 2‐[2‐hydroxy‐3‐methoxyphenyl]‐3‐[hydroxyl‐3‐methoxybenzylamino]‐1,2‐dihydroquin‐azoline‐4(3H)‐one (Hmpbaq) have been synthesized and characterized by elemental analysis, conductance measurements, magnetic susceptibilities, spectroscopic (IR, NMR, UV, EPR), and thermal studies. Molar conductance studies indicate 1: 1 electrolytic behavior for these complexes. IR spectra indicate that Hmpbaq acts as a tridentate ligand coordinating through carbonyl oxygen, benzyl amine nitrogen, and deprotonated phenolic oxygen. TG and DTA studies of La(III) and Pr(III) complexes indicate the presence of two coordinated water molecules. Based on these studies, the complexes have been formulated as [La(mpbaq)2(H2O)2]·NO3, where Ln = La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Th(III), Dy(III), and Y(III). The ligand, lanthanide(III) salts, and the corresponding complexes have been simultaneously screened for their antibacterial and antifungal activities and compared with the drugs in use.
Blockade of Cochlear NMDA Receptors Prevents Long-Term Tinnitus during a Brief Consolidation Window after Acoustic Trauma
Authors: Guitton Matthieu J. , Dudai Yadin
Published: February 2008

Tinnitus, the perception of sound in the absence of external acoustic stimulation, is a common and devastating pathology. It is often a consequence of acoustic trauma or drug toxicity. The neuronal mechanisms of tinnitus are neither yet fully understood nor are effective treatments available. Using a novel behavioral paradigm for measuring tinnitus in the rat based on tone-guided navigation, we show here that the development of long-term noise-induced tinnitus, the most prevalent and clinically important form of human tinnitus, can be abated by local administration of the NMDA antagonist “ifenprodil” into the cochlea in the first 4 days following the noise insult but not afterwards. This suggests that long-term tinnitus undergoes a consolidation-like process, resembling the ontogeny of items in long-term memory. Furthermore, this finding paves the way to potential therapeutic strategies for the prevention of chronic tinnitus once the noise insult had taken place.
Experimental Results for the Settling Behaviour of Particle‐Fiber Mixtures
Authors: Feist Markus , Nirschl Hermann , Wagner Jörg , Hirsch Georg , Schabel Samuel
Published: February 2008

Sedimentation of organic fibres and inorganic particles can be observed in several industrial applications. Fibres are involved not only in wastewater treatment but also in other separation applications. In the paper industry, the separation of inorganic filler and coating particles from short cellulose fibres is still a challenge in the recycling process. During that process, particles have to be removed to obtain a purified fibre suspension. These fibres can be used again to produce new paper. With the currently applied techniques, like screening and flotation, the efficiency of short fibre separation is very poor. Moreover, also separation by sedimentation fails due to similar settling velocities of heavy‐small particles and the light and larger fibres. This paper concentrates on the sedimentation of organic fibres and inorganic particles in water. The investigated suspensions are made by resolving two different and specially produced papers a coated and an uncoated one, as well as the single components used for its production. We observe a different sedimentation behaviour according to the concentration of fibres and particles in the suspension and the pH‐value of it. The main result is that, according to the fibre rate, the sedimentation behaviour is particle dominant or fibre dominant.
The P300 as a Marker of Waning Attention and Error Propensity
Authors: Datta Avijit , Cusack Rhodri , Hawkins Kari , Heutink Joost , Rorden Chris , Robertson Ian H. , Manly Tom
Published: February 2008

Action errors can occur when routine responses are triggered inappropriately by familiar cues. Here, EEG was recorded as volunteers performed a “go/no-go” task of long duration that occasionally and unexpectedly required them to withhold a frequent, routine response. EEG components locked to the onset of relevant go trials were sorted according to whether participants erroneously responded to immediatelysubsequentno-go trials or correctly withheld their responses. Errors were associated with a significant relative reduction in the amplitude of the preceding P300, that is, a judgement could be made bout whether a response-inhibition error was likely before it had actually occurred. Furthermore, fluctuations in P300 amplitude across the task formed a reliable associate of individual error propensity, supporting its use as a marker of sustained control over action.
Common QTL Affect the Rate of Tomato Seed Germination under Different Stress and Nonstress Conditions
Authors: Foolad Majid R. , Subbiah Prakash , Zhang Liping
Published: February 2008

The purpose of this study was to determine whether the rates of tomato seed germination under different stress and nonstress conditions were under common genetic controls by examining quantitative trait loci (QTL) affecting such traits. Seeds of BC1progeny of a cross between a slow-germinating tomato breeding line and a rapid-germinating tomato wild accession were evaluated for germination under nonstress as well as cold, salt, and drought stress conditions. In each treatment, the most rapidly-germinating seeds were selected, grown to maturity, and subjected to molecular marker analysis. A selective genotyping approach detected between 6 and 9 QTL affecting germination rate under each of the four conditions, with a total of 14 QTL identified. Ten QTL affected germination rate under 2 or 3 conditions, which were considered germination-related common QTL. Four QTL affected germination rate only in one treatment, which were considered germination-related, condition-specific QTL . The results indicated that mostly the same QTL affected seed germination under different stress and nonstress conditions, supporting a previous suggestion that similar physiological mechanisms contribute to rapid seed germination under different conditions. Marker-assisted selection for the common QTL may result in progeny with rapid seed germinability under different conditions.
Treatment of Diabetic Foot Ulcers in the Home: Video Consultations as an Alternative to Outpatient Hospital Care
Authors: Clemensen Jane , Larsen Simon B. , Kirkevold Marit , Ejskjaer Niels
Published: February 2008

The aim of this study was to investigate whether video consultations in the home can support a viable alternative to visits to the hospital outpatient clinic for patients with diabetic foot ulcers. And furthermore whether patients, relatives, visiting nurses, and experts at the hospital will experience satisfaction and increased confidence with this new course of treatment. Participatory design methods were applied as well as field observations, semistructured interviews, focus groups, and qualitative analysis of transcriptions of telemedical consultations conducted during a pilot test. This study shows that it is possible for experts at the hospital to conduct clinical examinations and decision making at a distance, in close cooperation with the visiting nurse and the patient. The visiting nurse experienced increased confidence with the treatment of the foot ulcer and characterized the consultations as a learning situation. All patients expressed satisfaction and felt confidence with this new way of working.
On the Spheroidal Semiseparation for Stokes Flow
Authors: Dassios George , Vafeas Panayiotis
Published: February 2008

Many heat and mass transport problems involve particle‐fluid systems, where the assumption of Stokes flow provides a very good approximation for representing small particles embedded within a viscous, incompressible fluid characterizing the steady, creeping flow. The present work is concerned with some interesting practical aspects of the theoretical analysis of Stokes flow in spheroidal domains. The stream function ψ, for axisymmetric Stokes flow, satisfies the well‐known equation E4ψ = 0. Despite the fact that in spherical coordinates this equation admits separable solutions, this property is not preserved when one seeks solutions in the spheroidal geometry. Nevertheless, defining some kind of semiseparability, the complete solution for ψ in spheroidal coordinates
has been obtained in the form of products combining Gegenbauer
functions of different degrees. Thus, the general solution is
represented in a full‐series expansion in terms of
eigenfunctions, which are elements of the space kerE2 (separable solutions), and in terms of generalized eigenfunctions, which are elements of the space kerE4 (semiseparable solutions). In this work
we revisit this aspect by introducing a different and simpler
way of representing the aforementioned generalized
eigenfunctions. Consequently, additional semiseparable solutions
are provided in terms of the Gegenbauer functions, whereas the
completeness is preserved and the full‐series expansion is
rewritten in terms of these functions.
The DiatomAnorthoneis dulcisHein from Southern Brazil: Morphology and Ecology
Authors: Marinês Garcia , Marciana Talgatti Dávia
Published: February 2008

A new geographic locality forAnorthoneis dulcisis reported. The paper describes the distribution and relative abundance ofA. dulcisin Lagoa dos Patos lagoon (a lagoon in Rio Grande do Sul state, Brazil) from samples collected between 2004 and 2005, and shows that this rare species is present all year round. This study extends the species distribution to South America indicating that the species can thrive on sand grains in lentic estuarine, and freshwater areas. It widens the range of tolerance to environmental parameters. The valve fine structure, morphology, and dimensions are in agreement with the original diagnosis.
Nanopinholes‐Based Optical Superlens
Authors: Fu Yongqi , Du Chunlei , Zhou Wei , Lim Lennie Enk Ng
Published: February 2008

A type of nanopinhole‐based plasmonic structure is presented. It can realize superfocusing within micron‐scale propagation distance with spatial resolution beyond diffraction limit. Cut‐off wavelength effect is highlighted for understanding how periodicity distribution of the nanopinholes influences transmission and focusing through the structure. Redshift peak transmission occurs while the periodicity increases. In addition, focusing property of the plasmonic structures is analyzed for the monochromatic illumination with different incident wavelengths ranging from 400 nm to 750 nm. The easy fabrication and high focusing performance of the proposed structures may be used in data storage devices, bioimaging, and nanolithography.
Mass-Charge and Energy Spectra of Oxygen Ions in a Two-Element Laser-Produced Plasma
Authors: Khaydarov R. T. , Kunishev U. S.
Published: February 2008

Using a static mass spectrometer, we study the characteristics of multicharge plasma ions generated from solid targets under the action of a
15 nanosecond Nd:YAG laser radiation with maximal intensity 1011 W/cm2. We consider two-element solid targets with a mass of the heavy component ranging from 44.9 (Sc) to 174.9 (Lu) with main attention to the properties of oxygen ions. The time-of-flight measurements show that oxygen ions are obtained in the range of the energy
E = 40–250 eV with maximal charge Zmax=2. The latter is independent on the target composition for the given intensity of the laser radiation. However, the properties of the energy spectra of oxygen ions strongly depend on the second component of the target, which is explained by the interaction between the light and heavy elements of the target.
Game Play Schemas: From Player Analysis to Adaptive Game Mechanics
Authors: Lindley Craig A. , Sennersten Charlotte C.
Published: February 2008

Schema theory provides a foundation for the analysis of game play patterns created by players during their interaction with a game. Schema models derived from the analysis of play provide a rich explanatory framework for the cognitive processes underlying game play, as well as detailed hypotheses for the hierarchical structure of pleasures and rewards motivating players. Game engagement is accounted for as a process of schema selection or development, while immersion is explained in terms of levels of attentional demand in schema execution. However, schemas may not only be used to describe play, but might be used actively as cognitive models within a game engine. Predesigned schema models are knowledge representations constituting anticipated or desired learned cognitive outcomes of play. Automated analysis of player schemas and comparison with predesigned target schemas can provide a foundation for a game engine adapting or tuning game mechanics to achieve specific effects of engagement, immersion, and cognitive skill acquisition by players. Hence, schema models may enhance the play experience as well as provide a foundation for achieving explicitly represented pedagogical or therapeutic functions of games.
Simple Correspondence Analysis of Nominal-Ordinal Contingency Tables
Authors: Beh Eric J.
Published: February 2008

The correspondence analysis of a two-way contingency table is now accepted as a very versatile tool for helping users to understand the structure of the association in their data. In cases where the variables consist of ordered categories, there are a number of approaches that can be employed and these generally involve an adaptation of singular value decomposition. Over the last few years, an alternative decomposition method has been used for cases where the row and column variables of a two-way contingency table have an ordinal structure. A version of this approach is also available for a two-way table where one variable has a nominal structure and the other variable has an ordinal structure. However, such an approach does not take into consideration the presence of the nominal variable. This paper explores an approach to correspondence analysis using an amalgamation of singular value decomposition and bivariate moment decomposition. A benefit of this technique is that it combines the classical technique with the ordinal analysis by determining the structure of the variables in terms of singular values and location, dispersion and higher-order moments.