bluuebunny/crossref_metadata_2025 huggingface dataset:
MULTIPARAMETER PARALLEL SEARCH BRANCH SWITCHING
Authors: HENDERSON MICHAEL E.
Published: May 2005

A continuation method (sometimes called path following) is a way to compute solution curves of a nonlinear system of equations with a parameter. We derive a simple algorithm for branch switching at bifurcation points for multiple parameter continuation, where surfaces bifurcate along singular curves on a surface. It is a generalization of the parallel search technique used in the continuation code AUTO, and avoids the need for second derivatives and a full analysis of the bifurcation point.

The one parameter case is special. While the generalization is not difficult, it is nontrivial, and the geometric interpretation may be of some interest. An additional tangent calculation at a point near the singular point is used to estimate the tangent to the singular set.
MODEL REDUCTION FOR FLUIDS, USING BALANCED PROPER ORTHOGONAL DECOMPOSITION
Authors: ROWLEY C. W.
Published: May 2005

Many of the tools of dynamical systems and control theory have gone largely unused for fluids, because the governing equations are so dynamically complex, both high-dimensional and nonlinear. Model reduction involves finding low-dimensional models that approximate the full high-dimensional dynamics. This paper compares three different methods of model reduction: proper orthogonal decomposition (POD), balanced truncation, and a method called balanced POD. Balanced truncation produces better reduced-order models than POD, but is not computationally tractable for very large systems. Balanced POD is a tractable method for computing approximate balanced truncations, that has computational cost similar to that of POD. The method presented here is a variation of existing methods using empirical Gramians, and the main contributions of the present paper are a version of the method of snapshots that allows one to compute balancing transformations directly, without separate reduction of the Gramians; and an output projection method, which allows tractable computation even when the number of outputs is large. The output projection method requires minimal additional computation, and has a priori error bounds that can guide the choice of rank of the projection. Connections between POD and balanced truncation are also illuminated: in particular, balanced truncation may be viewed as POD of a particular dataset, using the observability Gramian as an inner product. The three methods are illustrated on a numerical example, the linearized flow in a plane channel.
A BAYESIAN METANETWORK
Authors: TERZIYAN VAGAN
Published: June 2005

Bayesian network (BN) is known to be one of the most solid probabilistic modeling tools. The theory of BN provides already several useful modifications of a classical network. Among those there are context-enabled networks such as multilevel networks or recursive multinets, which can provide separate BN modelling for different combinations of contextual features' values. The main challenge of this paper is the multilevel probabilistic meta-model (Bayesian Metanetwork), which is an extension of traditional BN and modification of recursive multinets. It assumes that interoperability between component networks can be modeled by another BN. Bayesian Metanetwork is a set of BN, which are put on each other in such a way that conditional or unconditional probability distributions associated with nodes of every previous probabilistic network depend on probability distributions associated with nodes of the next network. We assume parameters (probability distributions) of a BN as random variables and allow conditional dependencies between these probabilities. Several cases of two-level Bayesian Metanetworks were presented, which consist on interrelated predictive and contextual BN models.
SUBSAMPLED MODEL AGGREGATION
Authors: KAO BEN , KATRIEL RON
Published: June 2005

There has been a recent push for a new framework of learning, due in part to the availability of storage, networking and the abundance of very large datasets. This framework argues for parallelized learning algorithms that can operate on a distributed platform and have the ability to terminate early in the likely event that data size is too inundating. Methods described herein propose a subsampled model aggregation technique based on the bagging algorithm. It is capable of significant run-time reduction with no loss in modeling performance. These claims were validated with a variety of base-learning algorithms on large web and newswire datasets.
PUSHING LOG-BASED RECONCILIATION
Authors: HAMADI YOUSSEF , SHAPIRO MARC
Published: June 2005

Optimistic reconciliation allows, multiple update of shared data without synchronization. The assumption is that the vast majority of the actions will not conflict. In these systems, write availability is raised in the presence of network failures, high latencies or parallel development. However, in order to remain consistent, optimistic systems repair divergences. To produce a new consistent state, they use the logs of each user in a process called log-based reconciliation. The purpose of an efficient reconciliation engine is then to compute a new consistent state which preserves the maximum of previous actions. This work leverages the efficiency of constraint-based reconciliation. It provides a new efficient two step procedure built by connecting theoretical results on backtrack-free search with this hard optimisation problem.
CONFLICTING AGENTS IN DISTRIBUTED SEARCH
Authors: HAMADI YOUSSEF
Published: June 2005

We extend here the work on interleaved distributed graph based backjumping, IDIBT/GBJ7,6,5 by considering conflicting agents.13 The resulting method IDIBT/CBJ-DkC for Conflict-directed Back-Jumbing and Directed k-Consistency combines distributed and parallel explorations of search spaces with more efficient backtrack steps. We take advantage of the asynchronous framework to implement a more refined and efficient update of conflicts. A fine analysis of these conflicts allows to some extent the detection of k-inconsistent values. Our experiments show a large improvement over graph based distributed/interleaved search.
METAMORPHOSIS: MINING MAXIMAL FREQUENT SETS IN DENSE DOMAINS
Authors: SRIKUMAR KRISHNAMOORTHY , BHASKER BHARAT
Published: June 2005

We present Metamorphosis, an algorithm for mining Maximal Frequent Sets (MFS) using novel data transformations. Metamorphosis transforms the dataset to Maximum Collapsible and Compressible (MC2) format and employs a top down strategy with phased bottom up search for efficiently mining MFS. Using a set of benchmark dense datasets such as chess, connect and pumsb, we demonstrate that our algorithm offers better performance in mining MFS compared to dGenMax (an algorithm that offers better performance compared to other known algorithms) at different support levels. Furthermore, we evaluate our algorithm for mining Top-K maximal frequent sets in dense domains.
THE HUGIN TOOL FOR PROBABILISTIC GRAPHICAL MODELS
Authors: MADSEN ANDERS L. , JENSEN FRANK , KJÆRULFF UFFE B. , LANG MICHAEL
Published: June 2005

As the framework of probabilistic graphical models becomes increasingly popular for knowledge representation and inference, the need for efficient tools for its support is increasing. The Hugin Tool is a general purpose tool for construction, maintenance, and deployment of Bayesian networks and influence diagrams. This paper surveys the key functionality of the Hugin Tool and reports on new advances of the tool. Furthermore, an empirical analysis reports on the efficiency of the Hugin Tool on common inference and learning tasks.
DEFORMATION ENERGIES OF NUCLEAR SYSTEMS
Authors: BŁOCKI J. , SHVEDOV L. , WILCZYŃSKI J.
Published: June 2005

We have extended a macroscopic model for calculating potential energy for nuclear shapes relevant in fusion and fission processes. Compared to the original approach [J. Blocki and W. J. Swiatecki, LBL-12811 (1982)], a more realistic model employing the Yukawa-plus-exponential folding potential and the Coulomb energy calculated for diffused charge distributions is proposed. The configuration space is extended to the regions which may be important for fusion of very heavy asymmetric nucleus-nucleus systems.
LIFETIME MEASUREMENTS IN 128Cs AND 132La AS A TEST OF CHIRALITY
Authors: GRODNER E. , ZALEWSKA I. , MOREK T. , SREBRNY J. , DROSTE CH. , KOWALCZYK M. , MIERZEJEWSKI J. , SAŁATA M. , PASTERNAK A. A. , KOWNACKI J. , KISIELIŃSKI M. , KORDYASZ A. , NAPIORKOWSKI P. , WOLIŃSKA M. , ROHOZIŃSKI S. G. , KACZAROWSKI R. , PŁÓCIENNIK W. , RUCHOWSKA E. , WASILEWSKI A. , PERKOWSKI J.
Published: June 2005

The lifetime of levels in 128 Cs and 132 La have been measured in-beam of the Warsaw University Cyclotron using DSA method. The absolute M1 and E2 transition probabilities have been deduced. Two cases have been found: 132 La where the B(E2) values in yrast and partner bands differ up to 30 times and 128 Cs - the B(E2) values in both bands differ only few times. It seems that bands in 128 Cs are better candidates for chiral partner bands than the ones in 132 La .
SEARCH FOR SHAPE COEXISTENCE IN 100Mo USING COULOMB EXCITATION
Authors: WRZOSEK K. , ZIELIŃSKA M. , CHOIŃSKI J. , CZOSNYKA T. , IWANICKI J. , KISIELIŃSKI M. , KOWALCZYK M. , NAPIORKOWSKI P. , REISSIG L. , SREBRNY J. , USHAKOV I. , ZAJAC K.
Published: June 2005

Coulomb excitation experiment of 100 Mo has recently been performed using 40 Ar beam from the Warsaw Cyclotron. Three lowest 2+ states, two 4+ and one 0+ excited states have been observed. It is a continuation of the systematic study of 96 Mo and 98 Mo nuclei having low lying 0+ excited state, with energy very close to the first 2+ state.
PROPERTIES OF SUPERHEAVY NUCLEI IN VARIOUS MACROSCOPIC-MICROSCOPIC MODELS
Authors: BARAN A. , KOWAL M. , ŁOJEWSKI Z. , SIEJA K.
Published: June 2005

In the framework of various macroscopic-microscopic models we examine the ground state properties: separation energies, mean square charge radii, electric quadrupole moments as well as fission barriers, mass parameters, spontaneous fission and α decay half-lives of superheavy nuclei. Four macroscopic models and two models of pairing interactions are applied and studied. The approach is based on the deformed Woods-Saxon potential. Spontaneous fission half-lives are calculated within a multi-dimensional dynamical-programming method where the action integral is minimized within the three dimensional space of the nuclear deformation parameters {β2, β4, β6}.
CROSS SECTIONS CALCULATED FOR COLD FUSION REACTIONS WITH EMISSION OF ONLY ONE NEUTRON FOR PRODUCING THE HEAVIEST ELEMENTS
Authors: SMOLAŃCZUK ROBERT
Published: June 2005

Entrance-channel effects in cold fusion reactions that lead to heavy and superheavy nuclei are discussed in the framework of the coupled-channels theory. Dynamical deformation besides collective excitations is taken into account in the entrance channel. Exit channel is described by using the modified statistical model that takes into account the difference between the level density in the equilibrium configuration and that in the saddle-point configuration. Comparison of the calculated fusion cross sections with experimental data is given.
SEARCH FOR THE TRI-AXIAL HEXADECAPOLE-DEFORMATION EFFECTS IN TRANS-ACTINIDAE NUCLEI
Authors: DUDEK J. , MAZUREK K. , NERLO-POMORSKA B.
Published: June 2005

We have performed calculations of the nuclear potential energies in a 5-dimensional space of deformation parameters including α20, α22, α40, α42 and α44 multipole deformations by using the macroscopic-microscopic method. The energy expression contains the macroscopic term (in our case in the form of the Lublin Strasbourg Drop – LSD) and the microscopic terms of the Strutinsky shell energy and projected BCS pairing energy. The single-particle energies are obtained from the classical mean-field potential as well as from the correspondig Dirac relativistic realisation of the mean-field, both parametrised with the help of the deformed Woods-Saxon forms. Our resuls are compared to the selfconsistent Hartree Fock Bogolubov method with the D1S Gogny force.
EXOTIC NUCLEAR SHAPES: TODAY AND TOMORROW
Authors: DUDEK J. , SCHUNCK N. , DUBRAY N. , GÓŹDŹ A.
Published: June 2005

After recalling some in principle known but seldom mentioned facts about variety of concepts/notions of the nuclear shapes, we briefly summarize the results of the recent microscopic calculations predicting the existence of the large-elongation (hyper-deformed) nuclear configurations — as well as another series of calculations predicting that some nuclei should exhibit high-rank symmetries: the tetrahedral and the octahedral ones. The latter are associated with 48- and 96- symmetry elements, respectively, of the nuclear mean-field Hamiltonian. Obviously the physics motivations behind the hyper-deformation and the high-rank symmetry studies are not the observations of the new geometrical forms as such; in our opinion these motivations are much deeper and are given in the text.
THE FISSION OF 252Cf FROM A MEAN FIELD PERSPECTIVE
Authors: WARDA M. , POMORSKI K. , EGIDO J. L. , ROBLEDO L. M.
Published: June 2005

The potential energy surface of 252 Cf has been computed within the Hartree-Fock-Bogolubov theory with the D1S Gogny force. The shape evolution of the nucleus during the fission process have been studied. Quadrupole, octupole and hexadecapole deformations have been taken into consideration.
SENSITIVITY OF ONE-QUASIPARTICLE SPECTRA OF HEAVIEST NUCLEI TO VARIOUS FACTORS
Authors: PARKHOMENKO A. , SOBICZEWSKI A.
Published: June 2005

Sensitivity of one-quasiparticle spectrum of a heavy nucleus to changes of such quantities as equilibrium deformation and pairing-interaction strength is studied. The study is done within a macroscopic-microscopic approach. The analysis is performed on the example of the nucleus 241 Am . Especially large sensitivity of the spectrum to changes of the quadrupole component of the equilibrium deformation is found.
QUASIPARTICLE PAIRS IN ODD-ODD NUCLEI
Authors: ROHOZIŃSKI STANISŁAW G. , STAROSTA KRZYSZTOF
Published: June 2005

In analogy to the core-quasiparticle coupling model used for investigation of the structure of odd-A nuclei a new way of description of odd-odd nuclei is presented being based on a symmetrical coupling of the two odd particles to the four neighboring even-even cores. The key feature of the model is an introduction of new objects: the quasiparticle pairs which are not systems of two independent quasiparticles. A method of selecting the physical solutions of the model is presented.
CRANKING OF NUCLEI AT FINITE TEMPERATURE: A SEMICLASSICAL APPROACH
Authors: BARTEL J. , BENCHEIKH K. , QUENTIN P.
Published: June 2005

We present a generalization of the Extended Thomas Fermi (ETF) theory to fermionic systems at finite temperature and finite angular momentum. In fact the present approach is more general in the sense that it is able to treat an excited system of fermions subject to an external vector field which in the case of nuclear rotations, developed more extensively here, is simply [Formula: see text].
QUADRUPOLE COLLECTIVE HAMILTONIAN WITH PAIRING VARIABLES INCLUDED
Authors: PRÓCHNIAK L.
Published: June 2005

We present a collective model which contains both deformation and pairing degrees of freedom. Coupling of these modes is important for a reliable treatment of the quadrupole dynamics in transitional nuclei. The microscopic part of the model contains the Nilsson potential and the seniority pairing force and the collective hamiltonian is obtained by the ATDHFB method. Results for γ soft nuclei 110 Ru and 126 Ba are shown.
SHELL AND PAIRING ENERGIES OBTAINED BY FOLDING IN THE PARTICLE NUMBER SPACE
Authors: POMORSKI K.
Published: June 2005

The Strutinsky shell correction method is modified. The smooth part of energy is evaluated by performing the Gauss-Hermite folding in the particle-number space, i.e. not over the single-particle energies as it was done in the old prescription.
THE PARTICLE CONSERVING SHELL CORRECTION METHOD AND THE NUCLEAR ZERO-POINT MOTION
Authors: MOLIQUE HERVÉ , DUDEK JERZY , POMORSKI KRZYSZTOF
Published: June 2005

We estimate the influence of the zero-point motion mechanism on the shell-energies calculated within the method of Strutinsky — applied for the doubly-magic spherical nuclei.
ERROR THRESHOLD ESTIMATION BY MEANS OF THE [[7,1,3]] CSS QUANTUM CODE
Authors: SALAS P. J. , SANZ A. L.
Published: May 2005

The states needed in quantum computation are extremely affected by decoherence. Several methods have been proposed to control error spreading. They use two main tools: fault-tolerant constructions and concatenated quantum error correcting codes. In this work, we estimate the threshold conditions necessary to make a long enough quantum computation. The [[7,1,3]] CSS quantum code together with the Shor method to measure the error syndrome is used. No concatenation is included. The decoherence is introduced by means of the depolarizing channel error model, obtaining several thresholds from the numerical simulation. Regarding the maintenance of a qubit stabilized in the memory, the error probability must be smaller than 2.9 × 10-5. In order to implement a one or two-qubit encoded gate in an effective fault-tolerant way, it is possible to choose an adequate non-encoded noisy gate if the memory error probability is smaller than 1.3 × 10-5. In addition, fulfilling this last condition permits us to assume a more efficient behavior compared to the equivalent non-encoded process.
Adipose-specific overexpression of GLUT4 reverses insulin resistance and diabetes in mice lacking GLUT4 selectively in muscle
Authors: Carvalho Eugenia , Kotani Ko , Peroni Odile D. , Kahn Barbara B.
Published: June 2005

Adipose tissue plays an important role in glucose homeostasis and affects insulin sensitivity in other tissues. In obesity and type 2 diabetes, glucose transporter 4 (GLUT4) is downregulated in adipose tissue, and glucose transport is also impaired in muscle. To determine whether overexpression of GLUT4 selectively in adipose tissue could prevent insulin resistance when glucose transport is impaired in muscle, we bred muscle GLUT4 knockout (MG4KO) mice to mice overexpressing GLUT4 in adipose tissue (AG4Tg). Overexpression of GLUT4 in fat not only normalized the fasting hyperglycemia and glucose intolerance in MG4KO mice, but it reduced these parameters to below normal levels. Glucose infusion rate during a euglycemic clamp study was reduced 46% in MG4KO compared with controls and was restored to control levels in AG4Tg-MG4KO. Similarly, insulin action to suppress hepatic glucose production was impaired in MG4KO mice and was restored to control levels in AG4Tg-MG4KO. 2-Deoxyglucose uptake during the clamp was increased approximately twofold in white adipose tissue but remained reduced in skeletal muscle of AG4Tg-MG4KO mice. AG4Tg and AG4Tg-MG4KO mice have a slight increase in fat mass, a twofold elevation in serum free fatty acids, an ∼50% increase in serum leptin, and a 50% decrease in serum adiponectin. In MG4KO mice, serum resistin is increased 34% and GLUT4 overexpression in fat reverses this. Overexpression of GLUT4 in fat also reverses the enhanced clearance of an oral lipid load in MG4KO mice. Thus overexpression of GLUT4 in fat reverses whole body insulin resistance in MG4KO mice without restoring glucose transport in muscle. This effect occurs even though AG4Tg-MG4KO mice have increased fat mass and low adiponectin and is associated with normalization of elevated resistin levels.
Initial entry of IRAP into the insulin-responsive storage compartment occurs prior to basal or insulin-stimulated plasma membrane recycling
Authors: Liu Gang , Hou June Chunqiu , Watson Robert T. , Pessin Jeffrey E.
Published: June 2005

To examine the acquisition of insulin sensitivity after the initial biosynthesis of the insulin-responsive aminopeptidase (IRAP), 3T3-L1 adipocytes were transfected with an enhanced green fluorescent protein-IRAP (EGFP-IRAP) fusion protein. In the absence of insulin, IRAP was rapidly localized (1–3 h) to secretory membranes and retained in these intracellular membrane compartments with little accumulation at the plasma membrane. However, insulin was unable to induce translocation to the plasma membrane until 6–9 h after biosynthesis. This was in marked contrast to another type II membrane protein (syntaxin 3) that rapidly defaulted to the plasma membrane 3 h after expression. In parallel with the time-dependent acquisition of insulin responsiveness, the newly synthesized IRAP protein converted from a brefeldin A-sensitive to a brefeldin A-insensitive state. The initial trafficking of IRAP to the insulin-responsive compartment was independent of plasma membrane endocytosis, as expression of a dominant-interfering dynamin mutant (Dyn/K44A) inhibited transferrin receptor endocytosis but had no effect on the insulin-stimulated translocation of the newly synthesized IRAP protein.
Localization and Connectivity in Spinal Interneuronal Networks: The Adduction–Caudal Extension–Flexion Rhythm in the Frog
Authors: Saltiel Philippe , Wyler-Duda Kuno , d'Avella Andrea , Ajemian Robert J. , Bizzi Emilio
Published: June 2005

We have previously reported that focal intraspinal N-methyl-d-aspartate (NMDA) iontophoresis in the frog elicits a motor output, which is organized in terms of its constituent isometric force directions at the ipsilateral ankle and its topography. Furthermore, the associated EMG patterns can be reconstructed as the linear combinations of seven muscle synergies, labeled A to G. We now focus on one of the most common NMDA-elicited outputs, the adduction–caudal extension–flexion rhythm, and examine the relationship between the different force phases in terms of synergies and topography. Two distinct EMG patterns produce caudal extensions, and only one of the two patterns is used at most sites. The key synergy combinations for the two patterns are B + e and D + c (strongest synergies capitalized). These two patterns map at distinct locations in the lumbar cord. Within individual sites rhythms, we find linkages among the synergies used to produce adductions, the onsets of flexions after caudal extensions, and the synergy pattern producing the caudal extensions. For example, the synergy composition of adductions at B + e caudal extension sites is dominated by E + b and at D + c caudal extension sites by C + d. The two types of adductions map at distinct locations, situated between the two caudal extension regions. Specifically the linked patterns of caudal extension–adduction interleave rostrocaudally in a CE2-ADD1-ADD2-CE1 sequence, where 1 and 2 refer to the two pattern types. The implications of this topography and connectivity with respect to motor systems organization and behaviors are discussed.
Low-Frequency Oscillations Arising From Competitive Interactions Between Visual Stimuli in Macaque Inferotemporal Cortex
Authors: Rollenhagen Julianne E. , Olson Carl R.
Published: June 2005

Some neurons in the inferotemporal cortex (IT) of the macaque monkey respond to visual stimuli by firing action potentials in a series of sharply defined bursts at a frequency of about 5 Hz. The aim of the present study was to test the hypothesis that the oscillatory responses of these neurons depend on competitive interactions with other neurons selective for different stimuli. To test this hypothesis, we monitored responses to probe images displayed in the presence of other already visible backdrop images. Two stimuli were used in testing each neuron: a foveal image that, when displayed alone, elicited an excitatory response (the “object”) and a peripheral image that, when displayed alone, elicited little or no activity (the “flanker”). We assessed the results of presenting these images separately and together in monkeys trained to maintain central fixation. Two novel phenomena emerged. First, displaying the object in the presence of the flanker enhanced the strength of the oscillatory component of the response to the object. This effect varied in strength across task contexts and may have depended on the monkey's allocating attention to the flanker. Second, displaying the flanker in the presence of the object gave rise to sometimes strong oscillations in which the initial phase was negative. This was all the more striking because the flanker by itself elicited little or no response. This effect was robust and invariant across task contexts. These results can be accounted for by competition between two neuronal populations, one selective for the object and the other for the flanker, if it is assumed that the visual responses of each population are subject to fatigue.
Anterior Cingulate Cortical Neuronal Activity During Perception of Noxious Thermal Stimuli in Monkeys
Authors: Iwata Koichi , Kamo Hiroshi , Ogawa Akiko , Tsuboi Yoshiyuki , Noma Noboru , Mitsuhashi Yutaka , Taira Masato , Koshikawa Noriaki , Kitagawa Junichi
Published: May 2005

It has been reported that the anterior cingulate cortex (ACC) has a variety of functions relating to pain as well as pain perception. However, the underlying mechanisms for those functions remain unclear. To elucidate the functional role of the ACC in pain perception and pain-related functions such as attention to pain and escape from pain, single neuronal activity was recorded from the ACC, and the behavioral correlates of this neuronal activity was studied. A total of 667 neurons were recorded from the ACC in awake behaving monkeys. Twenty-one had modulated activity during a heat-detection task. Eighteen of these increased their firing frequency following an increase in stimulus temperature, whereas three of them had decreased firing during heating of the face. Seventy-five percent of heat-evoked responses of heat-responsive ACC neurons were significantly depressed when monkeys detected the change in magnitude of illumination of a light presented on the front panel. The neuronal activity was significantly higher when monkeys escaped from a noxious heat stimulus than when the monkeys detected a small change in temperature (T2) above a larger initial shift (T1). No relationship between firing frequency and detection latency of the T2 stimulation was observed. These findings suggest that ACC nociceptive neurons are involved in attention to pain and escape from pain but not in the sensory discriminative aspect of pain.
Vagal-Evoked Activity in the Parafascicular Nucleus of the Primate Thalamus
Authors: Ito Shin-Ichi , Craig A. D.
Published: June 2005

The physiological effects of ascending vagal afferent activity in the primate forebrain have not been established, and because vagus nerve stimulation (VNS) is useful clinically for treatment of epilepsy and depression, these actions need to be identified. We used a roving microelectrode to record vagal-evoked potentials in the thalamus of the macaque monkey. In addition to the anticipated activation in the gustatory/visceral thalamic relay nucleus, we found an unexpectedly larger and earlier response focus with multi-unit discharges in the adjacent parafascicular nucleus. These data reveal a potent vagal input to this intralaminar nucleus, which is normally considered to be involved in motor control. This finding indicates that a role for this vagal activation site in the anti-epileptic effects of VNS needs to be considered.
Controlling Synaptic Input Patterns In Vitro by Dynamic Photo Stimulation
Authors: Boucsein Clemens , Nawrot Martin , Rotter Stefan , Aertsen Ad , Heck Detlef
Published: June 2005

Recent experimental and theoretical work indicates that both the intensity and the temporal structure of synaptic activity strongly modulate the integrative properties of single neurons in the intact brain. However, studying these effects experimentally is complicated by the fact that, in experimental systems, network activity is either absent, as in the acute slice preparation, or difficult to monitor and to control, as in in vivo recordings. Here, we present a new implementation of neurotransmitter uncaging in acute brain slices that uses functional projections to generate tightly controlled, spatio-temporally structured synaptic input patterns in individual neurons. For that, a set of presynaptic neurons is activated in a precisely timed sequence through focal photolytic release of caged glutamate with the help of a fast laser scanning system. Integration of synaptic inputs can be studied in postsynaptic neurons that are not directly stimulated with the laser, but receive input from the targeted neurons through intact axonal projections. Our new approach of dynamic photo stimulation employs functional synapses, accounts for their spatial distribution on the dendrites, and thus allows study of the integrative properties of single neurons with physiologically realistic input. Data obtained with our new technique suggest that, not only the neuronal spike generator, but also synaptic transmission and dendritic integration in neocortical pyramidal cells, can be highly reliable.
Role of Gap Junctions in Synchronized Neuronal Oscillations in the Inferior Olive
Authors: Leznik Elena , Llinás Rodolfo
Published: June 2005

Inferior olivary (IO) neurons are electrically coupled through gap junctions and generate synchronous subthreshold oscillations of their membrane potential at a frequency of 1–10 Hz. Whereas the ionic mechanisms of these oscillatory responses are well understood, their origin and ensemble properties remain controversial. Here, the role of gap junctions in generating and synchronizing IO oscillations was examined by combining intracellular recordings with high-speed voltage-sensitive dye imaging in rat brain stem slices. Single cell responses and ensemble synchronized responses of IO neurons were compared in control conditions and in the presence of 18β-glycyrrhetinic acid (18β-GA), a pharmacological gap junction blocker. Under our experimental conditions, 18β-GA had no adverse effects on intrinsic electroresponsive properties of IO neurons, other than the block of gap junction-dependent dye coupling and the resulting change in cells' passive properties. Application of 18β-GA did not abolish single cell oscillations. Pharmacologically uncoupled IO neurons continued to oscillate with a frequency and amplitude that were similar to those recorded in control conditions. However, these oscillations were no longer synchronized across a population of IO neurons. Our optical recordings did not detect any clusters of synchronous oscillatory activity in the presence of the blocker. These results indicate that gap junctions are not necessary for generating subthreshold oscillations, rather, they are required for clustering of coherent oscillatory activity in the IO. The findings support the view that oscillatory properties of single IO neurons endow the system with important reset dynamics, while gap junctions are mainly required for synchronized neuronal ensemble activity.
Auditory Thalamocortical Transmission Is Reliable and Temporally Precise
Authors: Rose Heather J. , Metherate Raju
Published: June 2005

We have used the auditory thalamocortical slice to characterize thalamocortical transmission in primary auditory cortex (ACx) of the juvenile mouse. “Minimal” stimulation was used to activate medial geniculate neurons during whole cell recordings from regular-spiking (RS cells; mostly pyramidal) and fast-spiking (FS, putative inhibitory) neurons in ACx layers 3 and 4. Excitatory postsynaptic potentials (EPSPs) were considered monosynaptic (thalamocortical) if they met three criteria: low onset latency variability (jitter), little change in latency with increased stimulus intensity, and little change in latency during a high-frequency tetanus. Thalamocortical EPSPs were reliable (probability of postsynaptic responses to stimulation was ∼1.0) as well as temporally precise (low jitter). Both RS and FS neurons received thalamocortical input, but EPSPs in FS cells had faster rise times, shorter latencies to peak amplitude, and shorter durations than EPSPs in RS cells. Thalamocortical EPSPs depressed during repetitive stimulation at rates (2–300 Hz) consistent with thalamic spike rates in vivo, but at stimulation rates ≥40 Hz, EPSPs also summed to activate N-methyl-d-aspartate receptors and trigger long-lasting polysynaptic activity. We conclude that thalamic inputs to excitatory and inhibitory neurons in ACx activate reliable and temporally precise monosynaptic EPSPs that in vivo may contribute to the precise timing of acoustic-evoked responses.
Motor Control of Rapid Sequential Finger Tapping in Humans
Authors: Arunachalam R. , Weerasinghe V. S. , Mills K. R.
Published: June 2005

We investigated in 29 healthy subjects a simple model of rapid independent finger movement: the rapid sequential tapping of adjacent fingers. Inter-tap interval (ITI) was measured for adjacent pairs of fingers in each direction. ITI was shorter in the ulnar→radial direction than in the reverse direction [ P < 0.001 for middle to index (M→I) compared with index to middle (I→M)]. There was a gradient across the hand such that in the ulnar→radial direction, little to ring (L→R) tapping was fastest and M→I slowest; in the radial→ulnar direction, the reverse was the case. Rectified surface electromyography (EMG) from finger extensors and flexors was averaged with respect to either the first or second tap. The interval between the flexor EMG burst and the tap was similar irrespective of the order of finger tapping, excluding a mechanical explanation of the timing difference. Transcranial magnetic stimulation (TMS) was applied at 0- to 50-ms intervals after the first tap. Interposed TMS delayed the second tap significantly more ( P < 0.001) in the M→I direction than in the I→M direction. Motor-evoked potentials (MEPs) evoked by TMS interposed between taps showed a greater facilitation in the M→I than in the I→M direction ( P < 0.001). Increasing intensity of TMS rendered subjects unable to produce the second tap, more frequently in the I→M direction than in the M→I direction. We have demonstrated a consistent pattern across the hand and postulate that finger-order-dependent differences in ITI and the gradient of these across the hand may reflect the mechanism of grasping and further that the cortical programming of finger tapping differs depending on finger order.
Neurosteroids Exhibit Differential Effects on mIPSCs Recorded From Normal and Seizure Prone Rats
Authors: Schwabe Kerstin , Gavrilovici Cezar , McIntyre Dan C. , Poulter Michael O.
Published: June 2005

In the perirhinal cortex of seizure prone (SP) rats, GABAA-mediated miniature inhibitory postsynaptic currents (mIPSCs) are smaller in amplitude but have longer deactivation phases than mIPSCs recorded in normal control (NC; outbred) rats. These differences in mIPSCs are correlated to the relatively higher α1 subunit expression in the NC rat strains and the higher α2, α3, and α5 subunit expression in the SP strain. Using patch-clamp recording, we investigated how the neurosteroids tetrahydrodeoxcorticosterone (THDOC) and allopregnanolone at physiological and pharmacological concentrations may differentially affect the mIPSCs in the perirhinal cortex of brain slices isolated from SP and NC rats. We found that 100 nM THDOC prolonged the time course and increased the amplitude of both the mono- and biphasic mIPSCs in the SP rats, but these effects were smaller in the NC rats. By comparison, allopregnanolone (100 nM) had small effects in both the NC and SP rats. At 1.0 μM, THDOC enhanced mIPSCs in both strains, but this effect was not greater in the SP rat than it was at 100 nM. By contrast, allopregnanolone (500 nM) enhanced the time course of the mIPSCs in both strains but it reduced mIPSC amplitudes as well. THDOC (100 nM) was much more effective than 100 nM allopregnanolone in inducing a tonic current in SP and NC rats. These data show that neurosteroids modulate synaptic activity at synapses having different biophysical behaviors. As differing GABAA receptors are targeted by subsets of interneurons, these data suggest these neurosteroids may selectively modulate one inhibitory input over another.
Design of an Automated Flow Injection‐Chemiluminescence Instrument Incorporating a Miniature Photomultiplier Tube for Monitoring Picomolar Concentrations of Iron in Seawater
Authors: Bowie Andrew R. , Achterberg Eric P. , Ussher Simon , Worsfold Paul J.
Published: June 2005

A flow‐injection (FI)‐based instrument under LabVIEW control for monitoring iron in marine waters is described. The instrument incorporates a miniature, low‐power photomultiplier tube (PMT), and a number of microelectric and solenoid actuated valves and peristaltic pumps. The software allows full control of all flow injection components and processing of the data from the PMT. The optimised system is capable of 20 injections per hour, including preconcentration and wash steps. The detection limit (3 sd of the blank) is 21 pM at sea and the linear range is 21–2000 pM with a 60‐second sample load time. Typical precision between replicate FI peaks is 5.9 ± 3.2% (n = 4) over the linear range.
Automated Quality Assurance of Online NIR Analysers
Authors: Aaljoki Kari
Published: June 2005

Modern NIR analysers produce valuable data for closed‐loop process control and optimisation practically in real time. Thus it is highly important to keep them in the best possible shape. Quality assurance (QA) of NIR analysers is an interesting and complex issue because it is not only the instrument and sample handling that has to be monitored. At the same time, validity of prediction models has to be assured. A system for fully automated QA of NIR analysers is described. The system takes care of collecting and organising spectra from various instruments, relevant laboratory, and process management system (PMS) data. Validation of spectra is based on simple diagnostics values derived from the spectra. Predictions are validated against laboratory (LIMS) or other online analyser results (collected from PMS). The system features automated alarming, reporting, trending, and charting functions for major key variables for easy visual inspection. Various textual and graphical reports are sent to maintenance people through email. The software was written with Borland Delphi 7 Enterprise. Oracle and PMS ODBC interfaces were used for accessing LIMS and PMS data using appropriate SQL queries. It will be shown that it is possible to take actions even before the quality of predictions is seriously affected, thus maximising the overall uptime of the instrument.
Mathematical Modeling of Perfect Decoupled Control System and Its Application: A Reverse Osmosis Desalination Industrial‐Scale Unit
Authors: Riverol C. , Pilipovik V.
Published: June 2005

This short paper outlines the computer simulation using real data of a decoupled control system for a desalination unit. The control strategy incorporated a perfect decoupled controller for the control of the fresh water flow and conductivity. The model was estimated using real data and empirical tools instead of mass balances. The success is demonstrated in the reduction of wide fluctuations in the variables of the process and decreasing of the sensibility to the changes of pressure and/or pH and allows predicting problems of quality of water and waste of energy in the future.
A New Analyzer Based on Pellistor Sensor with Neural Network Data Postprocessing for Measurement of Hydrocarbons in Lower Explosive Limit Range
Authors: Bandomir Radosław , Krawczyk Mariusz , Namieśnik Jacek
Published: June 2005

We present the results of a first stage of development work on a new type of analyzer for hydrogen and C1–C3 hydrocarbons concentration measurements in the lower explosive limit range, based on single pellistor sensor with artificial neural network data postprocessing.
Transforming Growth Factor-β Signaling during Epithelial-Mesenchymal Transformation: Implications for Embryogenesis and Tumor Metastasis
Authors: Nawshad Ali , LaGamba Damian , Polad Ahmad , Hay Elizabeth D.
Published: June 2005

The molecular mechanisms of epithelial-mesenchymal transformation (EMT) have long been studied to gain a greater understanding of this distinct change in cellular morphology. Early studies of the developing embryo have designated the involvement of Wnt signaling in EMT, through an activated complex of the lymphoid-enhancing factor-1 (LEF-1) transcription factor and the cell adhesion molecule β-catenin. However, more recent studies have implicated a significant role of the transforming growth factor-β (TGF-β) in causing EMT in both development and pathology. The ability of TGF-β isoforms to signal through a variety of molecules such as Smads, phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) creates an incredible complexity as to their role in this transition. Here we assess the biochemical signaling pathways of TGF-β and their potential cross-interaction with traditional Wnt signaling molecules to bring about EMT during embryogenesis and tumor metastasis.
Role of Interleukin-1β in the Development of Malnutrition in Chronic Renal Failure Patients
Authors: Maruyama Yukio , Stenvinkel Peter , Lindholm Bengt
Published: June 2005

Protein-energy malnutrition and wasting are common among patients with end-stage renal disease (ESRD) and these complications are strongly associated with poor survival in these patients. Whereas both under- and overweight predict in increased mortality risk in the general population, a high body mass index is associated with better outcome in ESRD patients. Circulating levels of pro-inflammatory cytokines are markedly elevated in uremia and also predictor of a poor clinical outcome in ESRD patients. Interleukin-1β (IL-1β), which is a major pro-inflammatory cytokine, may further amplify inflammation and lead to malnutrition, through inducing anorexia, and muscle wasting due to increased protein breakdown. Several clinical studies have shown that the circulating level of IL-1β may affect nutritional status, especially body composition. Several IL-1 gene cluster polymorphisms were reported, and they may affect the prevalence of cytokine-mediated diseases. Although a number of factors are related to malnutrition and wasting in ESRD, pro-inflammatory cytokines, such as IL-1β, may play an important role. This could in part be due to genetic factors. Further research, especially regarding the IL-1 gene cluster polymorphisms, is necessary to determine this hypothesis.
Particle Leakage in Extracorporeal Blood Purification Systems Based on Microparticle Suspensions
Authors: Hartmann Jens , Schildboeck Claudia , Brandl Martin , Falkenhagen Dieter
Published: June 2005

Aim: The newly developed ‘Microspheres based Detoxification System’ (MDS) designed for any extracorporeal adsorption therapy uses microparticles as adsorbents characterized by a size of 1–20 µm in diameter which are recirculated in the secondary (filtrate) circuit connected to a hollow fiber filter located in the primary (blood) circuit. In the case of a leakage or rupture in the hollow fiber filter, microspheres can enter patients’ blood circuits and cause embolic episodes in different organs with varying degrees of clinical relevance. Aim of this study was to determine the amount of particles infused to a patient during a long-term treatment under different failure conditions of the filter. Methods: The filters were prepared by cutting single hollow fibers. Fresh-frozen plasma (FFP) and a mixture of glycerol and water were used as a medium together with microparticles potentially used in the MDS.The amounts of particles transferred from the filtrate into the primary circuit were measured. Results: The analysis of particle transfer in the case of a single cut hollow fiber inside the membrane results in particle volumes of up to 26 ml calculated for 10 h. Conclusion: Particle leakage in microparticle suspension based detoxification systems can lead to considerable particle transfer to the patient. Therefore, a particle detection unit which is able to detect critical amounts of particles (<1 ml particle volume/treatment) in the extracorporeal blood line is necessary for patient safety.
Investigations of the Influence of External Nose Deformities on Nasal Airflow
Authors: Grützenmacher S. , Robinson D.M. , Lang C. , Lebe E. , Knape U. , Mlynski G.
Published: June 2005

Background: Abnormalities of the external shape of the nose are often felt as cosmetically disturbing. In many cases an additional hampering of the respiratory function of the nose is seen and causes pathological nasal airflow patterns. For the functional outcome of aesthetic-surgery of the nose, knowledge of nasal flow is essential. In the medical literature there are some discrepancies between the relationship of nasal shape and nasal flow. We investigated typical airflow patterns in different abnormalities of the external nose. Methods: We performed fluid dynamic experiments on exact, anatomical nasal models and functional nasal models (so-called modified Mink boxes). We investigated the inspiratory flow pattern in nose-models with typical variations of the shape of the external nose. Results and Conclusions: There were typical airflow patterns for every external nasal abnormalities. The normal nose shows a disturbance of the streamlines over the entire nasal cavum. Under physiological flow velocities we find laminar and turbulent flow. The pathological variations of the nasal shape show mostly different airflow patterns and characteristics. The main reason for that is a deformed or anatomically false configurated inflow area (vestibulum, isthmus and anterior cavum). During rhinoplasty the reconstruction of the nasal inflow area has to be taken into account.
Sizing of Atrial Septal Defects in Adults
Authors: Helgason Hrodmar , Johansson Magnus , Söderberg Björn , Eriksson Peter
Published: June 2005

In a retrospective study of 51 consecutive patients undergoing transcatheter closure of secundum type atrial septal defects (ASDs), we examined the reliability of transesophageal echocardiography (TEE) prior to catheterization and compared the diameter with that obtained by balloon measurement during catheterization. The TEE diameter was 16.3 ± 4.6 mm compared with 22.5 ± 6.0 mm for the stretched diameter obtained during catheterization (p < 0.001). There was no gender difference. The degree of left-to-right shunting correlated poorly with the size of the defect. We conclude that although TEE is accurate for diagnosis of an ASD, the measurement of its size to determine the size of the closure device is at best inaccurate.
The Prevalence of Common Cardiovascular Diseases among 17-Year-Old Israeli Conscripts
Authors: Bar-Dayan Yaron , Elishkevits Keren , Goldstein Liav , Goldberg Avishay , Ohana Nisim , Onn Erez , Levi Yehezkel , Bar-Dayan Yosefa
Published: June 2005

Background: There are only few reports on the prevalence of common cardiovascular disorders among adolescents. The previous studies focused on specific diseases, and screened relatively small samples. Objective: The aim of this study was to define the prevalence of different common cardiovascular disorders among 17-year-old Israeli conscripts. A comparison between the morbidity patterns of female and male adolescents was also performed. Design:All 17-years-old Israeli nationals are obliged by law to appear at the Israel Defense Forces Recruiting Office for medical examination except for orthodox religious and Arabic adolescents. Cardiology specialists evaluated and classified nominees with suspected cardiovascular disorders. Results: The most prevalent diagnoses were valvular heart disease (590/ 100,000), syncope (440/100,000), and mitral valve prolapse (340/100,000). The most prominent differences between female and male adolescents were noted in the prevalence of: congenital valvular heart disease, syncope, history of hypertension, supraventricular tachycardia with pre-excitation, myocarditis and pericarditis, and bradycardia and conduction disorders. Conclusions: The most prevalent cardiac disorders among 17-year-old Israelis were congenital valvular heart disease, syncope and mitral valve prolapse. Some significant differences were noted between the morbidity patterns among male and female adolescents. The higher prevalence of congenital valvular heart disease compared to non-valvular heart disease is surprising. The prevalence of hypertension among Israeli adolescents in the last 15 years remained stable.