bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of Cluster magnetic data with the Tsyganenko 2001 model
Authors: Woodfield E. E. , Dunlop M. W. , Holme R. , Davies J. A. , Hapgood M. A.
Published: June 2007

As part of an investigation of the magnetic effects of external currents in the magnetosphere, we have compared two years of perigee Cluster data to the Tsyganenko 2001 (T01) field model. Cluster data are not included in the T01 database and therefore can be used to independently verify the model. The model performs very well in a global sense; nevertheless, absolute residuals between the data and the model can reach ∼20 nT near perigee. These deviations take two forms: a sharp, bipolar signature and well‐defined trends over a larger spatial region. The bipolar signatures in the residuals are moderately stable, repeating on the phase period of the Cluster orbit. The bipolar nature of the signatures reflects variations in the Cluster data, therefore indicating that the spacecraft may be observing a field‐aligned current. Although the size of the magnetic field perturbation in this region is not well determined by T01, the location of the observed field‐aligned current system is accurately predicted. The bipolar signatures are observed in close proximity to the edge of the ring current, estimated from Cluster energetic electron spectrograms, indicating that they are associated with region 2 field‐aligned currents. Longer‐duration trends in the residuals indicate a slight difference between the model predictions and the Cluster data for various locations and seasons. For example, throughout most of 2003 and the first half of 2004, there is a residual in the total magnetic field for an hour centered on perigee, of ∼20 nT.
Complex systems analysis of series of blackouts: Cascading failure, critical points, and self-organization
Authors: Dobson Ian , Carreras Benjamin A. , Lynch Vickie E. , Newman David E.
Published: June 2007

We give an overview of a complex systems approach to large blackouts of electric power transmission systems caused by cascading failure. Instead of looking at the details of particular blackouts, we study the statistics and dynamics of series of blackouts with approximate global models. Blackout data from several countries suggest that the frequency of large blackouts is governed by a power law. The power law makes the risk of large blackouts consequential and is consistent with the power system being a complex system designed and operated near a critical point. Power system overall loading or stress relative to operating limits is a key factor affecting the risk of cascading failure. Power system blackout models and abstract models of cascading failure show critical points with power law behavior as load is increased. To explain why the power system is operated near these critical points and inspired by concepts from self-organized criticality, we suggest that power system operating margins evolve slowly to near a critical point and confirm this idea using a power system model. The slow evolution of the power system is driven by a steady increase in electric loading, economic pressures to maximize the use of the grid, and the engineering responses to blackouts that upgrade the system. Mitigation of blackout risk should account for dynamical effects in complex self-organized critical systems. For example, some methods of suppressing small blackouts could ultimately increase the risk of large blackouts.
Vibronic induced one- and two-photon absorption in a charge-transfer stilbene derivate
Authors: Lin Na , Zhao Xian , Rizzo Antonio , Luo Yi
Published: June 2007

Both the electronic and the vibronic contributions to one- and two-photon absorption of a D-π-D charge-transfer molecule (4-dimethylamino-4′-methyl-trans stilbene) are studied by means of density functional response theory combined with a linear coupling model. Vibronic profiles of the first four excited states are fully explored. The dominating vibrational modes for both Franck-Condon and Herzberg-Teller contributions are identified. The Franck-Condon contribution dominates the spectra of first, second, and fourth excited states. The Herzberg-Teller contribution is on the other hand of comparable size for the third excited state, where its inclusion leads to a blueshift with respect to the vertical transition. A similar vibronic coupling behavior is found for both one- and two-photon absorptions.
Compaction of microporous amorphous solid water by ion irradiation
Authors: Raut U. , Teolis B. D. , Loeffler M. J. , Vidal R. A. , Famá M. , Baragiola R. A.
Published: June 2007

We have studied the compaction of vapor-deposited amorphous solid water by energetic ions at 40K. The porosity was characterized by ultraviolet-visible spectroscopy, infrared spectroscopy, and methane adsorption/desorption. These three techniques provide different and complementary views of the structural changes in ice resulting from irradiation. We find that the decrease in internal surface area of the pores, signaled by infrared absorption by dangling bonds, precedes the decrease in the pore volume during irradiation. Our results imply that impacts from cosmic rays can cause compaction in the icy mantles of the interstellar grains, which can explain the absence of dangling bond features in the infrared spectrum of molecular clouds.
Semiconducting polymers and quantum dots in luminescent solar concentrators for solar energy harvesting
Authors: Sholin V. , Olson J. D. , Carter S. A.
Published: June 2007

We compare the performance of luminescent solar concentrators (LSCs) fabricated with polymers and quantum dots to the behavior of laser dye LSCs. Previous research, centered around the use of small molecule laser dyes, was hindered by the lack of materials with small absorption/emission band overlap and longer lifetime. Materials such as semiconducting polymers and quantum dots present qualities that are desirable in LSCs, for example, smaller absorption/emission band overlap, tunable absorption, and longer lifetimes. In this study, the efficiency of LSCs consisting of liquid solutions of semiconducting polymers encased in glass was measured and compared to the efficiency of LSCs based on small molecule dyes and on quantum dots. Factors affecting the optical efficiency of the system such as the luminescing properties of the organic materials were examined. The experimental results were compared to Monte Carlo simulations. Our results suggest that commercially available quantum dots cannot serve as viable LSC dyes because of their large absorption/emission band overlaps and relatively low quantum yields. Materials such as Red F demonstrate that semiconducting polymers with high quantum yield and small absorption/emission band overlap are good candidates for LSCs.
Time-dependent picture of the charge-transfer contributions to surface enhanced Raman spectroscopy
Authors: Lombardi John R. , Birke Ronald L.
Published: June 2007

We reexamine the Herzberg-Teller theory of charge-transfer contributions to the theory of surface enhanced Raman scattering (SERS). In previous work, the Kramers-Heisenberg-Dirac framework was utilized to explain many of the observed features in SERS. However, recent experimental and theoretical developments suggest that we revise the theory to take advantage of the time-dependent picture of Raman scattering. Results are obtained for molecular adsorption on nanoparticles in both the strong confinement limit and the weak confinement limit. We show that the Herzberg-Teller contributions to the charge-transfer effect in SERS display a resonance at the molecule-to-metal or metal-to-molecule transition while retaining the selection rules associated with normal Raman spectroscopy (i.e., harmonic oscillator, as opposed to Franck-Condon overlaps). The charge-transfer contribution to the enhancement factor scales as Γ−4, where Γ is the homogeneous linewidth of the charge-transfer transition, and thus is extremely sensitive to the magnitude of this parameter. We show that the Herzberg-Teller coupling term may be associated with the polaron-coupling constant of the surface phonon-electron interaction. A time-dependent expression for the Raman amplitude is developed, and we discuss the implications of these results for both metal and semiconductor nanoparticle surfaces.
Characterization of spectroscopic photoemission and low energy electron microscope using multipolarized soft x rays at BL17SU/SPring-8
Authors: Guo F. Z. , Muro T. , Matsushita T. , Wakita T. , Ohashi H. , Senba Y. , Kinoshita T. , Kobayashi K. , Saitoh Y. , Koshikawa T. , Yasue T. , Oura M. , Takeuchi T. , Shin S.
Published: June 2007

Spectroscopic photoemission and low energy electron microscope (SPELEEM) improved its performance after installation at BL17SU/SPring-8, where a multipolarization-mode undulator is employed to produce circularly and linearly polarized soft x rays. This undulator enables us to study the domain structures of ferromagnetic and antiferromagnetic materials by x-ray magnetic circular dichroism and x-ray magnetic linear dichroism. SPELEEM is used to study light elements (C, N, and O), 3d transition-metal elements and 4f rare earth elements, utilizing a wide range of photon energies. The two cylindrical mirrors adopted in front of SPELEEM ensure an illumination area of 14×14μm2 on the samples. The lateral resolution of a secondary electron photoemission electron microscope image is estimated to be better than 85nm, whereas the energy resolution of the instrument is better than 0.4eV.
Continuous-wave operation of electrically pumped, single-mode, edge-emitting photonic crystal Bragg lasers
Authors: Zhu Lin , Sun Xiankai , DeRose Guy A. , Scherer Axel , Yariv Amnon
Published: June 2007

The authors demonstrate an electrically pumped, single-mode, large-area, edge-emitting InGaAsP∕InP two dimensional photonic crystal Bragg laser operating in continuous-wave condition. The laser uses a weak index perturbed, polymer-planarized, surface photonic crystal structure to control the optical mode in the wafer plane. They find that the laser operates in single transverse and longitudinal modes. They compare the performance of the photonic crystal Bragg laser with a broad-area laser fabricated from the same wafer and the comparison shows that the performance penalty incurred by the photonic crystal is small.
Nematodes from the water dragon, Physignathus lesueurii (Reptilia:Agamidae) in Australia, with a description of Spinicauda fluviatica, sp. nov. (Nematoda:Heterakoidea)
Authors: Jones Hugh I.
Published: June 2007

Abbreviata physignathi and Spinicauda fluviatica, sp. nov., were the predominant species of nematode recovered from the gastrointestinal tracts of 65 Physignathus lesueurii examined from eastern Australia. S. fluviatica, sp. nov., is distinguished from other known species by the large well sclerotised excretory sinuses in both sexes and by the relative lengths of the spicules and gubernaculum in males. This is the first species of Spinicauda to be described from an agamid lizard. Both these nematode species occur mainly or entirely in New South Wales within 100 km of the coast; P. lesueurii is the only known host of both species. The persistence of generalised apical dentition in A. physignathi and its high host-specificity suggests a long association with this lizard, which diverged early from the main agamid stock. The significant association of these two unrelated nematode species is attributed to the high density of P. lesueurii hosts along suitable rivers. Other nematode species identified in low numbers in one or two hosts only were Abbreviata antarctica, A. confusa, Maxvachonia brygooi and immature Dracunculus sp. in the gastrointestinal tract, encysted subserosal physalopterid larvae on two stomachs, and Oswaldofilaria samfordensis in the body cavity.
Small Interfering RNA-mediated Silencing Induces Target-dependent Assembly of GW/P Bodies
Authors: Lian Shangli , Fritzler Marvin J. , Katz Joseph , Hamazaki Takashi , Terada Naohiro , Satoh Minoru , Chan Edward K.L.
Published: June 2007

Gene silencing using small interfering RNA (siRNA) is a valuable laboratory tool and a promising approach to therapeutics for a variety of human diseases. Recently, RNA interference (RNAi) has been linked to cytoplasmic GW bodies (GWB). However, the correlation between RNAi and the formation of GWB, also known as mammalian processing bodies, remains unclear. In this report, we show that transfection of functional siRNA induced larger and greater numbers of GWB. This siRNA-induced increase of GWB depended on the endogenous expression of the target mRNA. Knockdown of GW182 or Ago2 demonstrated that the siRNA-induced increase of GWB required these two proteins and correlated with RNAi. Furthermore, knockdown of rck/p54 or LSm1 did not prevent the reassembly of GWB that were induced by and correlated with siRNA-mediated RNA silencing. We propose that RNAi is a key regulatory mechanism for the assembly of GWB, and in some cases, GWB may serve as markers for RNAi in mammalian cells.
Low triiodothyronine: a strong predictor of outcome in acute stroke patients
Authors: Alevizaki M. , Synetou M. , Xynos K. , Pappa T. , Vemmos K. N.
Published: June 2007

Background  Low triiodothyronine (T3) has been associated with increased short‐term mortality in intensive care unit patients and long‐term mortality in patients with heart disease. The objective of this study was to investigate possible associations of thyroid hormone status with clinical outcome in patients admitted for acute stroke.

Materials and methods  A total of 737 consecutive patients with acute first ever stroke who presented within 24 h from symptoms’ onset were studied. Total T3, thyroxin (T4) and thyroid‐stimulating hormone (TSH) levels were assessed in the morning following admission. Cases with T3 values ≤ 78 ng dL−1 (1·2 nmol L−1) (median) were characterized as ‘low T3’. Cases with T4 values ≤ 4·66 µg dL−1 (60 nmol L−1) were characterized as ‘low T4’. Basic and clinical characteristics, stroke risk factors, and brain imaging were evaluated. Neurological impairment was assessed using the Scandinavian Stroke Scale.

Results  Four hundred and seventeen (56%) patients had T3 values ≤ 78 ng dL−1 and 320 had normal T3 values. The 1‐year mortality was 27·34% for low T3 and 19·37% for normal T3 cases (P = 0·006). A smaller percentage of patients with low T3 values were independent at 1 year compared to those with normal T3 values [54·2% vs. 68·7%, χ2 = 12·09, P < 0·001, odds ratio (OR) = 0·53, 95% confidence interval (CI) 0·37–0·76]. Cox regression analysis revealed that increased age, haemorrhagic stroke, low Scandinavian Stroke Scale score, increased glucose and low T3 values (hazards ratio 0·69, CI = 0·48–0·98, P = 0·041) were significant predictors of 1‐year mortality.

Conclusions  A high proportion of patients with acute stroke were found soon after the event with low T3 values. The low‐T3 syndrome is an independent predictor of early and late survival in patients with acute stroke, and predicts handicap at 1 year.
Caries prevalence in children with cleft lip and palate – a systematic review of case–control studies
Authors: HASSLÖF PAMELA , TWETMAN SVANTE
Published: June 2007

Aim.  To conduct a systematic review of literature in order to examine the evidence of an increased prevalence of dental caries in children with cleft lip and palate (CLP).

Methods.  A search of the PubMed database was conducted through May 2006. Sex‐ and age‐matched case–control studies with noncavitated and manifest caries lesions as endpoint were targeted (n = 6). The studies were assessed independently by two reviewers and scored A–C according to predetermined criteria for methodology and performance.

Results.  Significantly more caries in CLP children were reported in two of the four studies in the permanent dentition and in three out of four publications dealing with primary teeth. None of the articles were, however, assessed with the highest grade ‘A’ and the level of evidence was therefore based on three papers graded ‘B’. There was a tendency towards higher caries scores in preschool children, but as conflicting results were revealed, the evidence that children with CLP exhibit more caries than noncleft controls was inconclusive.

Conclusion.  This systematic review of literature was unable to find firm evidence for the assumption that CLP children have an increased prevalence of dental caries.
Antimicrobial susceptibility of 800 anaerobic isolates from patients with dentoalveolar infection to 13 oral antibiotics
Authors: Kuriyama T. , Williams D. W. , Yanagisawa M. , Iwahara K. , Shimizu C. , Nakagawa K. , Yamamoto E. , Karasawa T.
Published: June 2007

Introduction:  The aim of this study was to determine the current antimicrobial susceptibility of the principle anaerobic pathogens involved in dentoalveolar infection, to 13 oral antibiotics, and to assess the value of each antibiotic in the management of the infection.

Methods:  A total of 800 isolates from patients with dentoalveolar infection (Prevotella species, Fusobacterium species, Porphyromonas species and Peptostreptococcus micros) were tested for their susceptibility to amoxicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, cefcapene, cefdinir, erythromycin, azithromycin, telithromycin, minocycline, levofloxacin, clindamycin, and metronidazole using an agar dilution method.

Results:  Although the majority of Fusobacterium strains were resistant to erythromycin, azithromycin, and telithromycin, the remaining antibiotics demonstrated a high level of antimicrobial activity. P. micros and Porphyromonas species exhibited high susceptibility to all antibiotics tested in this study. In the case of Prevotella species, resistance to amoxicillin occurred in 34% of isolates and all of these resistant strains were found to produce β‐lactamase. Susceptibility of Prevotella strains to cefaclor, cefuroxime, cefcapene, cefdinir, erythromycin, azithromycin, and minocycline was found to correlate with amoxicillin susceptibility. Amoxicillin/clavulanate, telithromycin, clindamycin, and metronidazole exhibited high antimicrobial activity even against amoxicillin‐resistant strains of Prevotella species.

Conclusion:  Amoxicillin would still be advocated therefore as being a suitable first‐line agent, while reduced susceptibility of Prevotella strains remains a matter of concern with penicillins. Amoxicillin/clavulanate, clindamycin, and metronidazole are useful alternatives in combating the anaerobic bacteria involved in dentoalveolar infection.
The oligopeptide (opp) gene cluster of Streptococcus mutans: identification, prevalence, and characterization
Authors: Nepomuceno R. S. L. , Tavares M. B. , Lemos J. A. , Griswold A. R. , Ribeiro J. L. , Balan A. , Guimarães K. S. , Cai S. , Burne R. A. , Ferreira L. C. S. , Ferreira R. C. C.
Published: June 2007

Introduction:  The Opp system is an ATP‐binding cassette‐type transporter formed by membrane‐associated proteins required for the uptake of oligopeptides in bacteria. In gram‐positive bacteria, the Opp system, and particularly the oligopeptide‐binding protein (OppA), has been shown to be involved in different aspects of cell physiology, including intercellular communication and binding to host proteins.

Methods:  In the present study we began to investigate the Opp system of Streptococcus mutans, the main etiological agent of dental caries.

Results:  Five opp genes (oppABCDF) organized in a single operon were identified in the genome of the S. mutans UA159 strain. Amino acid sequence analyses showed that the S. mutans OppA is closely related to an ortholog found in Streptococcus agalactiae. Incubation of S. mutans UA159 cells with an anti‐OppA‐specific serum did not inhibit biofilm formation on polystyrene plates. Moreover, S. mutans UA159 derivatives carrying deletions on the oppA or oppB genes did not show significant growth impairment, increased sensitivity to aminopterin, or defective capacity to form biofilms on polystyrene wells in the presence or not of saliva. Remarkably, only two out of three laboratory strains and one out of seven clinical strains recovered from tooth decay processes harbored a copy of the oppA gene and expressed the OppA protein.

Conclusion:  Collectively, these results indicate that, in contrast to other Streptococcus species, the S. mutans Opp system, and particularly the OppA protein, does not represent an important trait required for growth and colonization.
Impaired single cell firing and long‐term potentiation parallels memory impairment following recurrent seizures
Authors: Zhou Jun‐Li , Shatskikh Tatiana N. , Liu Xianzeng , Holmes Gregory L.
Published: June 2007

Patients with epilepsy are at substantial risk for memory impairment. Animal studies have paralleled these clinical observations, demonstrating impaired hippocampal function as measured by spatial memory in rodents subjected to seizures. However, the mechanism of seizure‐induced hippocampal impairment is unclear. Here we investigated the effects of recurrent seizures on water‐maze performance, a behavioural measure of learning and memory, long‐term potentiation (LTP; considered a test of synaptic plasticity and memory) and place‐cell firing patterns, a single‐cell indicator of spatial memory. LTP and CA1 place‐cell activity were examined in separate groups of freely moving rats, before and after 10 flurothyl‐induced seizures. Water maze performance was examined in a third group of rats, five with previously induced seizures and five controls. Recurrent flurothyl seizures were associated with marked impairment in LTP and a reduction in the frequency of the peak theta power. Compared to baseline recordings, place‐cell firing patterns following recurrent seizures were significantly less precise, had lower firing rates and were less stable. Impaired place‐cell firing was seen as early as after two seizures and persisted at least 72 h after the last seizure. Water‐maze performance was also significantly impaired in animals that underwent recurrent seizures. No cell loss or synaptic reorganization was observed in the hippocampus or in several other cortical areas that are vulnerable to seizures. These results demonstrate that relatively brief excitatory events, not producing visible cell damage, can nevertheless cause long‐lasting changes in hippocampal physiology, observable as impairments in place‐cell function, LTP and spatial memory.
Anticipatory changes in beta synchrony in the human corticospinal system and associated improvements in task performance
Authors: Androulidakis Alexandros G. , Doyle Louise M. F. , Yarrow Kielan , Litvak Vladimir , Gilbertson Thomas P. , Brown Peter
Published: June 2007

Synchronized oscillatory activity in the beta frequency band (13–30 Hz) can be detected in the cerebral motor cortex of healthy humans in the form of corticomuscular coherence. Elevated beta activity is associated with impaired processing of new movements and with more efficient postural or tonic contraction. Accordingly, beta activity is suppressed prior to voluntary movements, rebounding thereafter in the face of peripheral afferance. However, it remains to be established whether synchronized activity in the beta band can be up‐regulated in a task‐appropriate way independently of confounding changes in sensory afferance. Here we show that there is a systematic and prospective increase in beta synchrony prior to an expected postural challenge. This up‐regulation of beta synchrony is associated with improved behavioural performance. We instructed nine healthy subjects to perform a reaction‐time movement of the index finger in response to an imperative visual cue or to resist a stretch to the finger in the same direction. These events were preceded by congruent and less common incongruent warning cues. Beta synchrony was temporally increased when subjects were warned of an impending stretch and decreased following a warning cue signalling a forthcoming reaction‐time task. Finger positions were less successfully maintained in the face of stretches and reaction times were longer when warning cues were incongruent. The results suggest that the beta state is modulated in a task‐relevant way with accompanying behavioural consequences.
Fibromyalgia patients show an abnormal dopamine response to pain
Authors: Wood Patrick B. , Schweinhardt Petra , Jaeger Erik , Dagher Alain , Hakyemez Helene , Rabiner Eugenii A. , Bushnell M. Catherine , Chizh Boris A.
Published: June 2007

Fibromyalgia is characterized by chronic widespread pain and bodily tenderness and is often accompanied by affective disturbances. Accumulating evidence indicates that fibromyalgia may involve a dysfunction of modulatory systems in the brain. While brain dopamine is best known for its role in pleasure, motivation and motor control, recent evidence suggests that it is also involved in pain modulation. Because dopamine is implicated in both pain modulation and affective processing, we hypothesized that fibromyalgia may involve a disturbance of dopaminergic neurotransmission. Fibromyalgia patients and matched healthy control subjects were subjected to deep muscle pain produced by injection of hypertonic saline into the anterior tibialis muscle. In order to determine the endogenous release of dopamine in response to painful stimulation, we used positron emission tomography to examine binding of [11C]‐raclopride (D2/D3 ligand) in the brain during injection of painful hypertonic saline and nonpainful normal saline. Fibromyalgia patients experienced the hypertonic saline as more painful than healthy control subjects. Control subjects released dopamine in the basal ganglia during the painful stimulation, whereas fibromyalgia patients did not. In control subjects, the amount of dopamine release correlated with the amount of perceived pain but in fibromyalgia patients no such correlation was observed. These findings provide the first direct evidence that fibromyalgia patients have an abnormal dopamine response to pain. The disrupted dopaminergic reactivity in fibromyalgia patients could be a critical factor underlying the widespread pain and discomfort in fibromyalgia and suggests that the therapeutic effects of dopaminergic treatments for this intractable disorder should be explored.
Injury‐induced neurogenesis in Bax‐deficient mice: evidence for regulation by voltage‐gated potassium channels
Authors: Shi Jian , Miles Darryl K. , Orr Benjamin A. , Massa Stephen M. , Kernie Steven G.
Published: June 2007

Adult neural stem and progenitor cells may help remodel the brain in response to injury. The pro‐apoptotic molecule Bax has recently been identified as a key player in adult neural stem cell survival. In Bax‐deficient mice that have undergone traumatic brain injury, we find increased numbers of neural progenitor cells in the dentate gyrus and improved remodeling of the hippocampus. Exogenous potassium chloride mimics spreading depression (SD)‐like eventsin vitro, and Bax‐deficient neural stem cells proliferate in response to these events more robustly than wild‐type neural stem cells. Selective potassium channel blockers interrupt SD‐mediated stimulation of stem cells. In addition, the potassium channel Kv4.1 is expressed within neural stem and progenitor cells in the dentate gyrus and is increased in Bax‐deficiency. These data suggest that the neuroprotection observed after injury in Bax‐deficiency may be due to increased neurogenesis via activation of the Kv4 family of potassium channels.
Further Insights into the Floral Character of Touriga Nacional Wines
Authors: De Pinho P. Guedes , Falqué E. , Castro M. , E Silva H. Oliveira , Machado B. , Ferreira A.C.Silva
Published: June 2007

ABSTRACT:  Higher‐quality Touriga Nacional (TN) wines are characterized by a fruity‐citric aroma described as sweet and fresh citrus evoking the bergamot fruit (Citrus bergamia). In fact, “bergamot‐like” descriptor is currently employed to rate higher quality TN wines. The aim of this work was to identify among volatile compounds present in bergamot fruit extracts (mainly terpenes) which of them contributes the most to the bergamot overall perception, and relate these data with the volatile composition of TN wines. The identification of the most important descriptors was done by sensory analysis. Among 18 descriptors 3 were selected: bergamot‐like aroma, orange like, and violet. A GCO of a typical TN wine extract allows the identification of 3 related odorant zones ZO1, ZO2, and ZO3 related with bergamot‐like aroma. Using AEDA, ZO2 was confirmed to be one of the most important odorant zones. Using AEDA the presence of linalool and linalyl acetate was confirmed. A similarity test was performed with a non‐TN wine added with linalool and linalyl acetate alone or in combinations. The highest similarity value was observed when linalool (SV = 5.9) was added. In fact, results obtained from the analysis of several red wines from different varieties show that terpenols are present in higher amounts in wines coming from TN variety, which proves that these compounds can be the clue to the varietal aroma of TN wines.
Soil Moisture Data Assimilation Using Support Vector Machines and Ensemble Kalman Filter1
Authors: Kashif Gill M. , Kemblowski Mariush W. , McKee Mac
Published: June 2007

Abstract:  A hybrid data assimilation (DA) methodology that combines two state‐of‐the‐art techniques, support vector machines (SVMs) and ensemble Kalman filter (EnKF), is applied for soil moisture DA in this work. The SVM methodology provides a statistically sound and robust approach to solving the inverse problem, and thus to building statistical models. EnKF is an extension of the Kalman Filter (KF), a well‐known tool in prediction updating. In the present research, ground measurements were used to build a SVM‐type soil moisture predictor. Subsequent observations and their statistics were assimilated to update predictions from the SVM model by coupling it with EnKF. In this way, both model predictions and ground data, as well as their statistics, are fused thus minimizing the prediction error and making the predictions and observations statistically consistent. The results are shown for two approaches; one in which update is done at every time step and the other which assumes that data is only available at alternate time steps (in window of 10 time steps) and hence update is performed at those occasions. The SVM‐EnKF coupling is shown to improve soil moisture forecasts in an example using data from the Soil Climate Analysis Network site at Ames, Iowa.
Cytokine and Chemokine Profiles following Vaccination with Human Papillomavirus Type 16 L1 Virus-Like Particles
Authors: García-Piñeres Alfonso , Hildesheim Allan , Dodd Lori , Kemp Troy J. , Williams Marcus , Harro Clayton , Lowy Douglas R. , Schiller John T. , Pinto Ligia A.
Published: June 2007

To determine the systemic cytokine pattern induced by vaccination with human papillomavirus (HPV) L1 virus-like particles (VLP), we analyzed 22 different cytokines in culture supernatants of L1 VLP-stimulated peripheral blood mononuclear cells from vaccine (n= 19) and placebo (n= 7) recipients at months 0 and 2 after vaccination, using a multiplex cytokine bead array. In vaccine recipients, incubation with L1 VLP in vitro led to a statistically significant increase in production of Th1 (granulocyte-macrophage colony-stimulating factor, interleukin-2 [IL-2], gamma interferon;P< 0.0007) and Th2 (IL-4, IL-5, IL-10, IL-13;P< 0.0017) cytokines and the chemokine IP-10 (P= 0.0021) at month 2 after immunization, compared to levels seen prior to vaccination. These responses were not seen in placebo recipients. Cytokine and neutralizing antibody responses to vaccination followed the same pattern, with the highest antibody responses seen for subjects with higher cytokine responses. Cytokine profiling studies using samples from efficacy trials may provide important information about discriminators of long-term protection against HPV.
Use of Bronchoalveolar Lavage To Detect Galactomannan for Diagnosis of Pulmonary Aspergillosis among Nonimmunocompromised Hosts
Authors: Nguyen M. Hong , Jaber Reia , Leather Helen L. , Wingard John R. , Staley Benjamin , Wheat L. Joseph , Cline Christina L. , Baz Maher , Rand Kenneth H. , Clancy Cornelius J.
Published: June 2007

Pulmonary aspergillosis in nonimmunocompromised hosts, although rare, is being increasingly recognized. The diagnosis of pulmonary aspergillosis is difficult, since the recovery of
Aspergillus
from respiratory samples cannot differentiate colonization from invasion. We assessed the role of bronchoalveolar lavage (BAL) in detecting galactomannan (GM) for diagnosing pulmonary aspergillosis in 73 nonimmunocompromised patients with pulmonary infiltrates for whom the test was ordered. Six patients had pulmonary aspergillosis, two each with acute invasive pulmonary aspergillosis, chronic necrotizing pulmonary aspergillosis, and aspergilloma. All six patients had a BAL GM level of ≥1.18. The sensitivity, specificity, and negative predictive value (NPV) for a BAL GM level of ≥1.0 were 100%, 88.1%, and 100%, respectively. Notably, the positive predictive value (PPV) was only 42.9%, likely reflecting the low prevalence of pulmonary aspergillosis among nonimmunosuppressed patients. The combination of BAL microscopy and culture had a sensitivity and NPV similar to those of BAL GM detection but a higher specificity and PPV (92.5% and 54.6%, respectively). Moreover, a BAL GM test did not identify any cases that were not diagnosed by conventional methods like microscopy and culture. In conclusion, there was no conclusive benefit of determining BAL GM levels in the diagnosis of pulmonary aspergillosis among nonimmunocompromised hosts. Given the likelihood of false-positive results, a BAL GM test should not be ordered routinely in this population.
Use of Quantitative PCR and Culture Methods To Characterize Ecological Flux in Bacterial Biofilms
Authors: Dalwai F. , Spratt D. A. , Pratten J.
Published: June 2007

An in vitro model of supragingival plaque associated with gingivitis was characterized by traditional culture techniques, comparative 16S rRNA gene sequencing of isolates, and quantitative PCR (QPCR).
Actinomyces naeslundii
,
Prevotella
spp., and
Porphyromonas gingivalis
increased under conditions emulating gingivitis. Gram-negative species and total bacteria were dramatically underestimated by culture compared to the estimates obtained by QPCR.
When Workers Disunite: Intraspecific Parasitism by Eusocial Bees
Authors: Beekman Madeleine , Oldroyd Benjamin P.
Published: June 2007

One of the most obvious characteristics of an insect society is reproductive cooperation. Yet insect colonies are vulnerable to reproductive parasitism, both by workers from their own colony and by workers from others. Little is known about the mechanisms insect societies have evolved to protect themselves from being exploited from within and outside the colony and the mechanisms that social parasites have evolved to circumvent these mechanisms. Here we showcase recently discovered cases of intraspecific parasitism by workers in eusocial bees. These discoveries overturn the widespread view that insect colonies are like fortresses populated by female eunuchs, and yield important insights into the mechanisms that normally enforce functional worker sterility.
Role of RYR3 splice variants in calcium signaling in mouse nonpregnant and pregnant myometrium
Authors: Dabertrand Fabrice , Fritz Nicolas , Mironneau Jean , Macrez Nathalie , Morel Jean-Luc
Published: June 2007

Alternative splicing of ryanodine receptor subtype 3 (RYR3) may generate a short isoform (RYR3S) without channel function and a functional full-length isoform (RYR3L). The RYR3S isoform has been shown to negatively regulate the native RYR2 subtype in smooth muscle cells as well as the RYR3L isoform when both isoforms were coexpressed in HEK-293 cells. Mouse myometrium expresses only the RYR3 subtype, but the role of RYR3 isoforms obtained by alternative splicing and their activation by cADP-ribose during pregnancy have never been investigated. Here, we show that both RYR3S and RYR3L isoforms are differentially expressed in nonpregnant and pregnant mouse myometrium. The use of antisense oligonucleotides directed against each isoform indicated that only RYR3L was activated by caffeine and cADP-ribose in nonpregnant myometrium. These RYR3L-mediated Ca2+ releases were negatively regulated by RYR3S expression. At the end of pregnancy, the relative expression of RYR3L versus RYR3S and its ability to respond to cADP-ribose were increased. Therefore, our results suggest that physiological regulation of RYR3 alternative splicing may play an essential role at the end of pregnancy.
Glucocorticoids increase salt appetite by promoting water and sodium excretion
Authors: Thunhorst Robert L. , Beltz Terry G. , Johnson Alan Kim
Published: June 2007

Glucocorticoids [e.g., corticosterone and dexamethasone (Dex)], when administered systemically, greatly increase water drinking elicited by angiotensin and sodium ingestion in response to mineralocorticoids [e.g., aldosterone and deoxycorticosterone acetate (DOCA)], possibly by acting in the brain. In addition, glucocorticoids exert powerful renal actions that could influence water and sodium ingestion by promoting their excretion. To test this, we determined water and sodium intakes, excretions, and balances during injections of Dex and DOCA and their coadministration (DOCA+Dex) at doses commonly employed to stimulate ingestion of water and sodium. In animals having only water to drink, Dex treatment greatly increased water and sodium excretion without affecting water intake, thereby producing negative water and sodium balances. Similar results were observed when Dex was administered together with DOCA. In animals having water and saline solution (0.3 M NaCl) to drink, Dex treatment increased water and sodium excretion, had minimal effects on water and sodium intakes, and was associated with negative water and sodium balances. DOCA treatment progressively increased sodium ingestion, and both water and sodium intakes exceeded their urinary excretion, resulting in positive water and sodium balances. The combination of DOCA+Dex stimulated rapid, large increases in sodium ingestion and positive sodium balances. However, water excretion outpaced total fluid intake, resulting in large, negative water balances. Plasma volume increased during DOCA treatment and did not change during treatment with Dex or DOCA+Dex. We conclude that increased urinary excretion, especially of water, during glucocorticoid treatment may explain the increased ingestion of water and sodium that occurs during coadministration with mineralocorticoids.
PKA phosphorylation of SUR2B subunit underscores vascular KATP channel activation by beta-adrenergic receptors
Authors: Shi Yun , Wu Zhongying , Cui Ningren , Shi Weiwei , Yang Yang , Zhang Xiaoli , Rojas Asheebo , Ha Binh T. , Jiang Chun
Published: June 2007

ATP-sensitive K+ (KATP) channels are activated by several vasodilating hormones and neurotransmitters through the PKA pathway. Here, we show that phosphorylation at Ser1387 of the SUR2B subunit is critical for the channel activation. Experiments were performed in human embryonic kidney (HEK) 293 cells expressing the cloned Kir6.1/SUR2B channel. In whole cell patch, the Kir6.1/SUR2B channel activity was stimulated by isoproterenol via activation of β2 receptors. This effect was blocked in the presence of inhibitors for adenylyl cyclase or PKA. Similar channel activation was seen by exposing inside-out patches to the catalytic subunit of PKA. Because none of the previously suggested PKA phosphorylation sites accounted for the channel activation, we performed systematic mutational analysis on Kir6.1 and SUR2B. Two serine residues (Ser1351, Ser1387) located in the NBD2 of SUR2B were critical for the channel activation. In vitro phosphorylation experiments showed that Ser1387 but not Ser1351 was phosphorylated by PKA. The PKA-dependent activation of cell-endogenous KATP channels was observed in acutely dissociated mesenteric smooth myocytes and isolated mesenteric artery rings, where activation of these channels contributed significantly to the isoproterenol-induced vasodilation. Taken together, these results indicate that the Kir6.1/SUR2B channel is a target of β2 receptors and that the channel activation relies on PKA phosphorylation of SUR2B at Ser1387.
Functional MRI Analysis of Body and Body Part Representations in the Extrastriate and Fusiform Body Areas
Authors: Taylor John C. , Wiggett Alison J. , Downing Paul E.
Published: June 2007

This study examined the contributions of two previously identified brain regions—the extrastriate and fusiform body areas (EBA and FBA)—to the visual representation of the human form. Specifically we measured in these two areas the magnitude of fMRI response as a function of the amount of the human figure that is visible in the image, in the range from a single finger to the entire body. A second experiment determined the selectivity of these regions for body and body part stimuli relative to closely matched control images. We found a gradual increase in the selectivity of the EBA as a function of the amount of body shown. In contrast, the FBA shows a steplike function, with no significant selectivity for individual fingers or hands. In a third experiment we demonstrate that the response pattern seen in EBA does not extend to adjacent motion-selective human midtemporal area. We propose an interpretation of these results by analogy to nearby face-selective regions occipital face area (OFA) and fusiform face area (FFA). Specifically, we hypothesize that the EBA analyzes bodies at the level of parts (as has been proposed for faces in the OFA), whereas FBA (by analogy to FFA) may have a role in processing the configuration of body parts into wholes.
Tuning to Sound Frequency in Auditory Field Potentials
Authors: Kayser Christoph , Petkov Christopher I. , Logothetis Nikos K.
Published: June 2007

Neurons in auditory cortex are selective for the frequency content of acoustical stimuli. Classically, this response selectivity is studied at the single-neuron level. However, current research often employs functional imaging techniques to investigate the organization of auditory cortex. The signals underlying the imaging data arise from neural mass action and reflect the properties of populations of neurons. For example, the signal used for functional magnetic resonance imaging (fMRI-BOLD) was shown to correlate with the oscillatory activity quantified by local field potentials (LFPs). This raises the questions of how the frequency selectivity in neuronal population signals compares with the tuning of spiking responses. To address this, we quantified tuning properties of auditory-evoked potentials (AEP), different frequency bands of the LFP, analog multi-unit (AMUA), and spike-sorted single- and multiunit activity in auditory cortex. The AMUA showed a close correspondence in frequency tuning to the spike-sorted activity. In contrast, for the LFP, we found a clear dissociation of high- and low-frequency bands: there was a gradual increase of tuning-curve similarity, tuning specificity, and information about the stimulus with increasing LFP frequency. Although properties of the high-frequency LFP matched those of spiking activity, the lower-frequency bands differed considerably as did the AEP. These results demonstrate that electrophysiological population responses exhibit varying degrees of frequency tuning and suggest that those functional imaging methods that are related to high-frequency oscillatory activity should well reflect the neuronal processing of sound frequency.
Contrast Adaptation in a Nonadapting LGN Model
Authors: Gaudry Kate S. , Reinagel Pamela
Published: June 2007

Sensory neurons appear to adapt their gain to match the variance of signals along the dimension they encode, a property we shall call “contrast normalization.” Contrast normalization has been the subject of extensive physiological and theoretical study. We previously found that neurons in the lateral geniculate nucleus (LGN) exhibit contrast normalization in their responses to full-field flickering white-noise stimuli, and that neurons with the strongest contrast normalization best preserved information transmission across a range of contrasts. We have also shown that both of these properties could be reproduced by nonadapting model cells. Here we present a detailed comparison of this nonadapting model to physiological data from the LGN. First, the model cells recapitulated other contrast dependencies of LGN responses: decreasing stimulus contrast resulted in an increase in spike-timing jitter and spike-number variability. Second, we find that the extent of contrast normalization in this model depends on model parameters related to refractoriness and to noise. Third, we show that the model cells exhibit rapid, transient changes in firing rate just after changes in contrast, and that this is sufficient to produce the transient changes in information transmission that have been reported in other neurons. It is known that intrinsic properties of neurons change during contrast adaptation. Nevertheless the model demonstrates that the spiking nonlinearity of neurons can produce many of the temporal aspects of contrast gain control, including normalization to input variance and transient effects of contrast change.
A Model of V4 Shape Selectivity and Invariance
Authors: Cadieu Charles , Kouh Minjoon , Pasupathy Anitha , Connor Charles E. , Riesenhuber Maximilian , Poggio Tomaso
Published: June 2007

Object recognition in primates is mediated by the ventral visual pathway and is classically described as a feedforward hierarchy of increasingly sophisticated representations. Neurons in macaque monkey area V4, an intermediate stage along the ventral pathway, have been shown to exhibit selectivity to complex boundary conformation and invariance to spatial translation. How could such a representation be derived from the signals in lower visual areas such as V1? We show that a quantitative model of hierarchical processing, which is part of a larger model of object recognition in the ventral pathway, provides a plausible mechanism for the translation-invariant shape representation observed in area V4. Simulated model neurons successfully reproduce V4 selectivity and invariance through a nonlinear, translation-invariant combination of locally selective subunits, suggesting that a similar transformation may occur or culminate in area V4. Specifically, this mechanism models the selectivity of individual V4 neurons to boundary conformation stimuli, exhibits the same degree of translation invariance observed in V4, and produces observed V4 population responses to bars and non-Cartesian gratings. This work provides a quantitative model of the widely described shape selectivity and invariance properties of area V4 and points toward a possible canonical mechanism operating throughout the ventral pathway.
Spectral Theory from the Second-Orderq-Difference Operator
Authors: Dhaouadi Lazhar
Published: June 2007

Spectral theory from the second-orderq-difference operatorΔqis developed. We give an integral representation of its inverse, and the resolvent operator is obtained. As application, we give an analogue of the Poincare inequality. We introduce the Zeta function for the operatorΔqand we formulate some of its properties. In the end, we obtain the spectral measure.