Temporal Degradation Research Articles

Contrasting Propagation of Natural Calls of Two Anuran Species from the South American Temperate Forest.

The acoustic adaptation hypothesis predicts that sound communication signals have an optimal relationship with animals’ native environments. However, species sharing a habitat produce signals stratified in the spectral domain and exhibit different temporal patterns resulting in acoustic niche partitioning. The diversity generated is likely to affect differently the characteristics of propagating signals. We recorded at various distances from the sound source calls of the frogs Eupsophus calcaratus and E. emiliopugini in the austral temperate forest where they communicate and breed syntopically. The calls of E. calcaratus have higher frequency components and lower amplitude relative to calls of E. emiliopugini, and the acoustic active space for the signals of E. calcaratus is restricted relative to E. emiliopugini. The signals of both species experience similar attenuation patterns, but calls of E. calcaratus are affected by spectral degradation to a larger extent, with linear decreases in spectral cross-correlation and in the amplitude ratio between the first two harmonics. The calls of E. emiliopugini are affected by temporal degradation as a linear decrease in amplitude modulation depth of their pulsed structure. Further studies are needed to assess the relative importance of selective and phylogenetic factors on the divergent propagation patterns reported.

Proteasomes, Sir2, and Hxk2 Form an Interconnected Aging Network That Impinges on the AMPK/Snf1-Regulated Transcriptional Repressor Mig1

Elevated proteasome activity extends lifespan in model organisms such as yeast, worms and flies. This pro-longevity effect might be mediated by improved protein homeostasis, as this protease is an integral module of the protein homeostasis network. Proteasomes also regulate cellular processes through temporal and spatial degradation of signaling pathway components. Here we demonstrate that the regulatory function of the proteasome plays an essential role in aging cells and that the beneficial impact of elevated proteasome capacity on lifespan partially originates from deregulation of the AMPK signaling pathway. Proteasome-mediated lifespan extension activity was carbon-source dependent and cells with enhancement proteasome function exhibited increased respiratory activity and oxidative stress response. These findings suggested that the pro-aging impact of proteasome upregulation might be related to changes in the metabolic state through a premature induction of respiration. Deletion of yeast AMPK, SNF1, or its activator SNF4 abrogated proteasome-mediated lifespan extension, supporting this hypothesis as the AMPK pathway regulates metabolism. We found that the premature induction of respiration in cells with increased proteasome activity originates from enhanced turnover of Mig1, an AMPK/Snf1 regulated transcriptional repressor that prevents the induction of genes required for respiration. Increasing proteasome activity also resulted in partial relocation of Mig1 from the nucleus to the mitochondria. Collectively, the results argue for a model in which elevated proteasome activity leads to the uncoupling of Snf1-mediated Mig1 regulation, resulting in a premature activation of respiration and thus the induction of a mitohormetic response, beneficial to lifespan. In addition, we observed incorrect Mig1 localization in two other long-lived yeast aging models: cells that overexpress SIR2 or deleted for the Mig1-regulator HXK2. Finally, compromised proteasome function blocks lifespan extension in both strains. Thus, our findings suggest that proteasomes, Sir2, Snf1 and Hxk2 form an interconnected aging network that controls metabolism through coordinated regulation of Mig1.

The degradation of proteins in pinniped skeletal muscle: viability of post-mortem tissue in physiological research.

As marine divers, pinnipeds have a high capacity for exercise at depth while holding their breath. With finite access to oxygen, these species need to be capable of extended aerobic exercise and conservation of energy. Pinnipeds must deal with common physiological hurdles, such as hypoxia, exhaustion and acidosis, that are common to all exercising mammals. The physiological mechanisms in marine mammals used for managing oxygen and carbon dioxide have sparked much research, but access to animals and tissues is difficult and requires permits. Deceased animals that are either bycaught or stranded provide one potential source for tissues, but the validity of biochemical data from post-mortem samples has not been rigorously assessed. Tissues collected from stranded diving mammals may be a crucial source to add to our limited knowledge on the physiology of some of these animals and important to the conservation and management of these species. We aim to determine the reliability of biochemical assays derived from post-mortem tissue and to promote the immediate sampling of stranded animals for the purpose of physiological research. In this study, we mapped the temporal degradation of muscle enzymes from biopsied Northern elephant seals (Mirounga angustirostris) and highlight recommendations for storage protocols for the best preservation of tissue. We also compared the enzymatic activity of different muscle groups (pectoral and latissimus dorsi) in relation to locomotion and measured the effects of four freeze-thaw cycles on muscle tissue enzyme function. Results indicate that enzymatic activity fluctuates greatly, especially with varying storage temperature, storage time, species and muscle group being assayed. In contrast, proteins, such as myoglobin, remain relatively continuous in their increase at 4°C for 48 h. Stranded animals can be a valuable source of biochemical data, but enzyme assays should be used only with great caution in post-mortem tissues.

Radiometric Non-Uniformity Characterization and Correction of Landsat 8 OLI Using Earth Imagery-Based Techniques

Landsat 8 is the first satellite in the Landsat mission to acquire spectral imagery of the Earth using pushbroom sensor instruments. As a result, there are almost 70,000 unique detectors on the Operational Land Imager (OLI) alone to monitor. Due to minute variations in manufacturing and temporal degradation, every detector will exhibit a different behavior when exposed to uniform radiance, causing a noticeable striping artifact in collected imagery. Solar collects using the OLI’s on-board solar diffuser panels are the primary method of characterizing detector level non-uniformity. This paper reports on an approach for using a side-slither maneuver to estimate relative detector gains within each individual focal plane module (FPM) in the OLI. A method to characterize cirrus band detector-level non-uniformity using deep convective clouds (DCCs) is also presented. These approaches are discussed, and then, correction results are compared with the diffuser-based method. Detector relative gain stability is assessed using the side-slither technique. Side-slither relative gains were found to correct streaking in test imagery with quality comparable to diffuser-based gains (within 0.005% for VNIR/PAN; 0.01% for SWIR) and identified a 0.5% temporal drift over a year. The DCC technique provided relative gains that visually decreased striping over the operational calibration in many images.

Output temporal contrast simulation of a large aperture high power short pulse laser system

Abstract The work presented in this paper is a study of output temporal contrast degradation by near-field quality deterioration, such as intensity modulation and wavefront deviation, in a large aperture high power short pulse laser system. A two-step focusing algorithm with a coordinate transform based on the Fresnel approximation in the space domain is used for simulating the output focused by an off-axis parabolic mirror. The temporal contrast degradation by intensity modulation and wavefront deviation is analyzed and the influence of the diameter on the temporal contrast degradation is revealed. The simulation and assumption results based on the parameters of the Shen Guang-II laser system are compared with the online experimental temporal contrast data. The near-field quality deterioration might lead to temporal contrast degradation, hindering higher temporal contrast in large aperture high power short pulse laser systems.

Investigating motion blur and temporal aliasing from time-lapse electrical resistivity

Geophysical monitoring through time-lapsed resistivity imaging is investigated to determine detrimental effects resulting from temporal smear. Temporal smear can be divided into motion blur and temporal aliasing, with motion blur attributed to an extended sample integration time relative to the velocity of a moving target, thus giving rise to reproduced targets that are distorted versions of the real target shape. Aliasing results from undersampling across time and may give a discontinuous movement. The degree to which each aspect of smear affects target properties described by spatial moment analysis depends on the spatial resolution of the imaging method and the degree to which temporal degradation is applied. For synthetic models with relatively high spatial resolution, aliasing effects were slight except in cases where the minimal number of snapshots was acquired to understand the end state condition of the target. Motion blur, on the other hand, had progressive detrimental effects with each level of additional smearing. For field data acquired during subsurface injection with a lower resolution array, the damaging effects from motion blur and temporal aliasing were equivalent. Both aspects showed progressive degeneration of spatial moments with each level of degradation. To combat this problem in the short term, it is recommended to acquire resistivity data as rapidly as possible and sacrifice some spatial resolution to enhance temporal resolution. In the future, there may be methods adopted from motion photography to deblur target motion by using the point spread function. Aliasing, however, can only be solved through continuous sampling.

Precompensation of gain nonuniformity in a Nd:glass amplifier using a programmable beam-shaping system

A programmable liquid crystal beam-shaping system was installed for a 200-mJ optical parametric chirped-pulse amplification (OPCPA) system front end and was applied to dramatically improve the beam uniformity in the subsequent amplifier. A highly nonuniform beam profile caused by gain inhomogeneity in the amplifier was pre-compensated by the beam shaping system using significantly improved open-loop and closed-loop algorithms. The details of the improved algorithms will be described. The issues of running a liquid crystal device with a high-energy, ultrashort-pulse laser, such as damage risk and temporal contrast degradation, will be addressed.

Abstract 46: Temporal Ubiquitin-Proteasomal Degradation of Smad9 Mediated by its Specific E3 Ligase Asb2 is Required for Cardiac Development through the Regulation of Tbx2 Expression

Background: The bone morphogenetic protein (BMP) pathway plays crucial roles in cardiac development. Recent studies have reported that mutations in Smad9, one of the regulatory Smad specific for the BMP pathway, might result in cardiovascular diseases. However, both regulation and function of Smad9 in the cardiovascular system have not been elucidated. Methods and Results: We conducted DNA microarray using P19CL6 cells with forced expression of Smad9. Microarray analysis using Ingenuity Pathway Analysis elucidated that 19 genes including Tbx2 were related to BMP pathway and showed significantly altered expression levels by transient expression of Smad9. We confirmed by qRT-PCR that only Tbx2, but not other Tbx families, were induced by Smad9. Importantly, the expression of Tbx2 was more up-regulated by Smad9 than by Smad1. Moreover, we identified Asb2 as a specific E3 ligase that targets Smad9, but not Smad1/5, for proteasomal degradation. The in situ hybridization using murine embryo revealed that Asb2 is expressed predominantly in the heart during embryonic development, suggesting that Asb2 quantitatively regulates Smad9 in the developing heart. Biochemical analysis demonstrated that Tbx2 expression induced by Smad9 was attenuated by Asb2, which was restored by the treatment with proteasome inhibitor, lactacystin. Developmental studies using both P19CL6 cells and zebrafish showed that the ablation of Asb2 leads accumulation of Smad9 resulting in the up-regulation of Tbx2, which attenuates myocardial development while induces non-myocardial tissue including cardiac cushion. Indeed, alcian blue staining of morpholino-mediated knockdown of zebrafish Asb2 showed significantly dilated ventricle and thinned ventricular wall, accompanied with decreased myocardium and increased cardiac jelly. Conclusions: Smad9 induces the expression of Tbx2 during cardiac development and is temporally and quantitatively regulated by its specific E3 ligase Asb2. This is the first study to show both the target gene and specific E3 ligase of Smad9.

Bionanoparticles as candidate reference materials for mobility analysis of nanoparticles.

We propose bionanoparticles as a candidate reference material for determining the mobility of nanoparticles over the range of 6 × 10(-8)-5 × 10(-6) m(2)V(-1)s(-1). Using an electrospray differential mobility analyzer (ES-DMA), we measured the empirical distribution of several bionanoparticles. All of them show monomodal distributions that are more than two times narrower than the currently used calibration particles for mobility larger than 6 × 10(-8) m(2)V(-1)s(-1) (diameters less than 60 nm). We also present a numerical method to calculate corrected distributions of bionanoparticles by separating the contribution of the diffusive transfer function. The corrected distribution is about 20% narrower than the empirical distributions. Even with the correction, the reduced width of the mobility distribution is about a factor of 2 larger than the diffusive transfer function. The additional broadening could result from the nonuniform conformation of bionanoparticles and from the presence of volatile impurities or solvent adducts. The mobilities of these investigated bionanoparticle are stable over a range of buffer concentration and molarity, with no evidence of temporal degradation over several weeks.

Stochastic Modeling of Positive Bias Temperature Instability in High-$\kappa $ Metal Gate nMOSFETs

Positive bias temperature instability (PBTI) has become one of the major reliability concerns in the present day CMOS technology. The PBTI mostly degrades the performance of high- \(\kappa \) /metal gate (HK/MG) nMOSFETs and is dominated by time dependent stress induced trap generation. The PBTI models proposed so far in different literature are deterministic in nature and overlook the randomness of the temporal degradation of transistor threshold voltage, \(V_{\rm th}\) . In this paper, we present a stochastic model for PBTI to predict the behavior of HK/MG nMOSFETs under inversion mode stress. The model is scalable and is verified against experimental data from two different groups. Our model separately considers each trap to predict their impact on device performance. The simulations are carried out at accelerated voltage and temperature conditions and we noted the variations in \(V_{\rm th}\) . In addition, we have analyzed the impact of PBTI on the performance of a ring oscillator and concluded that the circuit speed suffers significant degradation due to this effect. We have also observed that the adverse effect of PBTI becomes more severe as we go deeper into the nanometer technology.

Recovery of organic-enriched sediments through microbial degradation: implications for eutrophic estuaries

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 503:41-58 (2014) - DOI: https://doi.org/10.3354/meps10747 Recovery of organic-enriched sediments through microbial degradation: implications for eutrophic estuaries Thomas Valdemarsen1,*, Cintia O. Quintana1,2, Erik Kristensen1, Mogens R. Flindt1 1Institute of Biology, University of Southern Denmark, 5230 Odense M, Denmark 2Institute of Oceanography, University of São Paulo, São Paulo 05508-070, Brazil *Corresponding author: valdemarsen@biology.sdu.dk ABSTRACT: Sediments in eutrophic estuarine ecosystems may become heavily enriched with organic carbon (OC). This OC is primarily of low reactivity and, therefore, has moderate effects on sediment biogeochemical cycling. Nonetheless, OC levels of >1% reduce sediment stability and cause frequent resuspensions and high water turbidity, which affect the recovery of ecosystem functioning. Significant reduction of sediment OC content to <1% is, therefore, needed before ecosystems can fully recover. It was investigated whether organic-rich sediments with 2.5 to 4.4% OC (180–310 mol m–2) from the eutrophic Odense Fjord (Denmark) can recover by microbial degradation. Defaunated sediment cores from various habitats were subjected to long-term (~2 yr) degradation experiments. Total OC content was measured initially and OC degradation was measured regularly from CO2 effluxes and closed anoxic sediment incubations. OC degradation was high initially, but faded exponentially at all stations before stabilizing at 6 to 15 mmol OC m-2 d-1 after 100 to 150 d. Hence, over the 2 yr experiment OC degradation corresponded to only 3 to 5% reduction of initial OC. Temporal degradation patterns analyzed by exponential decay models suggested that sedimentary OC consisted of 2 pools with different reactivity plus a non-reactive pool. OC with the highest turnover (k = 0.5 × 10-2 to 5.5 × 10-2 d-1) was quantitatively the least important (0.3-4.3% of total OC), while OC with lower reactivity (k = 0.1 × 10-3 to 2.0 × 10-3 d-1) constituted a higher proportion (4-58% of total OC in organic-rich sediments). Furthermore, 43 to 95% of sediment OC was non-degradable. Our results suggest that partial recovery (5-57% reduction of initial OC) may occur within 23 to 50 yr. However, complete recovery of organic-rich sediments to <1% OC seems unlikely due to large pools of non-reactive OC. Eutrophication, therefore, leads to irreversible OC accumulation in sediments, which prolongs the recovery time for estuarine ecosystems after reductions in nutrient loading. KEY WORDS: Organic matter · Degradation · Mineralization · Oligotrophication · Recovery time · Exponential decay · G-model Full text in pdf format PreviousNextCite this article as: Valdemarsen T, Quintana CO, Kristensen E, Flindt MR (2014) Recovery of organic-enriched sediments through microbial degradation: implications for eutrophic estuaries. Mar Ecol Prog Ser 503:41-58. https://doi.org/10.3354/meps10747 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 503. Online publication date: April 29, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Using total OH reactivity to assess isoprene photooxidation via measurement and model

The Tropics provide a reactive atmospheric environment with high levels of biogenic emissions, rapidly growing anthropogenic influence, high solar radiation and temperature levels. The major reactive biogenic emission is isoprene which reacts rapidly with the primary daytime oxidant OH, the hydroxyl radical. This key photooxidation process has recently been the focus of several experimental and computational studies. A novel isoprene degradation mechanism was recently proposed (MIME) supplementing the commonly used MCM 3.2 scheme.This study examined the photooxidation of isoprene in the controlled conditions of the Valencia atmospheric reaction chamber, EUPHORE (EUropean PHOtoREactor). Besides the detection of isoprene and its major oxidation products formaldehyde, methyl vinyl ketone (MVK) and methacrolein (MACR), the total loss rate of OH (total OH reactivity) was measured. The total OH reactivity was compared to the individual measurements of isoprene and its oxidation products to assess the significant contributors to the overall OH loss rate. Measured total OH reactivity showed excellent agreement to the calculation based on individual compounds detected by a Proton-Transfer-Reaction-Time-Of-Flight-Mass-Spectrometer (PTR-TOF-MS). On average 97% of the measured total OH reactivity could be explained by isoprene and its major oxidation products.Total OH reactivity was also compared to various isoprene degradation schemes to evaluate known mechanisms. The MCM 3.2 isoprene mechanism reproduced the temporal degradation of total OH reactivity (and isoprene) reasonably well with a 57% (and 95%) agreement within the model uncertainties and a linear curve fit slope of 0.69 (and 1.02) for a model to measurement correlation. Large discrepancies between modeled values and all observed compounds were found for the recent isoprene oxidation scheme in MIME. Possible mechanistic reasons are discussed and improvements proposed. The subsequently modified version of MIME differed from the measured total OH reactivity only about 12% at the end of the experiment and represented best the overall temporal profile (linear curve fit slope of correlation: 0.95).

Continuous observation of polarization effects in thin SC-CVD diamond detector designed for heavy ion microbeam measurement

Continuous irradiation effects on a thin-film diamond detector were investigated for the utilization of these films as a detector for heavy ion microbeams. Temporal signal degradation in the energy spectrum was frequently observed during the focused heavy ion microbeam irradiation. To measure the temporal response to the each ion incidents, focused heavy ion microbeam with different beam fluence rates were irradiated to a single crystal (SC)-CVD diamond film detector with thickness of 50μm. The responses to each ion were continuously observed and characterized by ion beam-induced charge (IBIC) measurement system. Heavy ions with short penetration path in diamond generate the large difference in mean path of electrons and holes, which is inverted by changing bias polarity. Signal degradation condition was relied on the bias polarity under the irradiation of heavy ions with short penetration length in the diamond. The continuous observation of IBIC signals revealed that temporal degradation in pulse height of signals, so called polarization effects, seems to be mainly caused by the hole trapping in this diamond crystal.

Macroscopic In-Situ Modeling of Chemical Membrane Degradation in Polymer Electrolyte Fuel Cells

Chemical membrane degradation is a major limiting factor for polymer electrolyte fuel cell (PEFC) durability and lifetime. While the main degradation mechanisms are established in the literature, the in-situ trends of their action are often only known qualitatively. This motivates the development of a comprehensive in-situ chemical membrane degradation model addressed in this work. The numerical algorithms developed are strategically designed to be compatible with state-of-the-art computational membrane electrolyte assembly (MEA) performance models; here, we emphasize the integration of the developed degradation model into a 1-D MEA transport-reaction model to determine the linkages between the MEA macroscopic phenomena, in-situ operating conditions, and the temporal membrane degradation process. Concentrations of hydrogen peroxide, radical, and degraded ionomer species are modeled to interrogate the evolution of ionomer molecular structure with respect to the chemical membrane degradation. The proposed degradation mechanism includes the initiation and propagation of side chain degradation culminating in main chain scission and fragmentation, and demonstrates a good agreement with the most recent experimental findings. The integrated MEA model is further applied to simulate the macroscopic effects of chemical membrane degradation characterized in a recent accelerated stress test. Comparisons between the numerical and experimental results are discussed.

种族偏见的神经生理机制

早期种族偏见的ERP研究多集中在相对较晚的加工阶段，近来研究者越来越关注种族偏见相关的早期的认知加工，研究中涉及到了P100、N170、P200、SPCN等ERP指标。种族偏见相关的fMRI研究，主要涉及到了其神经机制和面孔加工、评价等过程之间的关系。种族偏见的认知加工过程并不是固定不变的，而是会受到心理因素、个体经历、群际关系、社会环境等因素的调节。未来可以结合迭代再加工模型，以杏仁核、前颞叶等重要脑区的研究为基础，深入考察种族偏见的形成和消退机制以及动机对种族偏见的调节机制。Early ERP researches on racial prejudice concerned later components of processing, while more attention is paid on early stages of cognitive processing (P100, N170, P200, SPCN) recently. Race-related fMRI researches mainly examine how racial bias is related to processes such as face processing, evaluation and so on. The neural processing of racial bias, which is not unalterable, is also under the influence of psychological factors, individual experience, intergroup relationship and social environment. In future, combining with iterative reprocessing model, based on neurophysiological researches on amygdala and anterior temporal lobe activity, the formation and degradation mechanism of racial prejudice and the regulatory mechanism of motivation to racial prejudice will be investigated in depth.

Hijacking the host proteasome for the temporal degradation of bacterial effectors.

To establish infection, intracellular pathogens need to modulate host cellular processes. Modulation of host processes is achieved by the action of various "effector proteins" which are delivered from the bacteria to the host cell cytosol. In order to orchestrate host cell reprogramming, the function of effectors inside host cells is regulated both temporally and spatially. In eukaryotes one of the most prominent processes used to degrade proteins is the ubiquitin-proteasome system. Recently it has emerged that the intracellular pathogen Legionella pneumophila is able to achieve temporal regulation of an effector using the ubiquitin-proteasome system. After establishing its replicative niche, the L. pneumophila effector SidH is degraded by the host proteasome. Most remarkably another effector protein LubX is able to mimic the function of an eukaryotic E3 ubiquitin ligase and polyubiquitinates SidH, targeting it for degradation. In this paper we describe a method to detect the polyubiquitin-modified forms of SidH in vitro and in vivo. Analyzing the temporal profile of polyubiquitination and degradation of bacterial effectors aids towards our understanding of how bacteria hijack host systems.

Abstract 9798: The E3 lLgase Asb2 Regulates Cardiac Development Through Targeting Smad9 for Proteasomal Degradation

A growing body of evidence revealed that temporal regulation of transcriptional factors is crucially required for cardiac development. Although the induction of transcription factors such as Nkx2.5 and Tbx5 has been of particular interest, the role and mechanism of their timely down-regulation during cardiac development is not fully elucidated. We hypothesized that E3 ligase-dependent degradation of transcription factors plays crucial roles in cardiac development. To identify key E3 ligases regulating cardiac development, we induced three different populations of cardiomyocytes from murine embryonic stem cells treated with any of Noggin, Frizzled or vehicle. We analyzed the temporal changes in gene expressions of them and finally identified an E3 ligase, namely ankyrin repeat and socs box protein2 (Asb2). Both whole mount in situ hybridization of mouse embryos and subsequent RT-PCR revealed that the Asb2β transcript, an isoform of Asb2, is present predominantly in heart during the early embryonic stage. We found that Smad9, an intracellular transducer of the bone morphogenetic protein signals, interact with Asb2β. Biochemical analysis revealed that Asb2β specifically ubiquitinate Smad9, but not Smad1/5. Pulse chase analysis demonstrated that Smad9 was targeted for proteasomal degradation by Asb2β. Knockdown of zebrafish asb2 using morpholino caused significant thinning of the ventricular wall (3.6 ± 0.9 vs. 8.7 ± 1.0μm, p &lt;0.01 ) and remarkable dilatation of the ventricular diameter (23.7 ± 1.1 vs. 11.3 ± 0.7μm, p&lt;0.01 ) compared with wild type siblings. Importantly, simultaneous knockdown of smad9 rescued the impairment of cardiac development due to asb2 knockdown in zebrafish, whereas single knockdown of smad9 caused no abnormal phenotype. These results imply that the suppression of Smad9 is crucial for cardiac development. Also we confirmed that forced expressions of Smad9 in P19CL6 cells failed in cardiac differentiation while that of Asb2β did not affect their fate. We conclude that the accumulation of Smad9 critically impairs the cardiac development and the temporal degradation of Smad9 mediated by E3 ligase Asb2 is critically required for cardiognesis.

Gender Categorization in Cochlear Implant Users

In this study, the authors examined the ability of subjects with cochlear implants (CIs) to discriminate voice gender and how this ability evolved as a function of CI experience. The authors presented a continuum of voice samples created by voice morphing, with 9 intermediate acoustic parameter steps between a typical male and a typical female. This method allowed for the evaluation of gender categorization not only when acoustical features were specific to gender but also for more ambiguous cases, when fundamental frequency or formant distribution were located between typical values. Results showed a global, though variable, deficit for voice gender categorization in CI recipients compared with subjects with normal hearing. This deficit was stronger for ambiguous stimuli in the voice continuum: Average performance scores for CI users were 58% lower than average scores for subjects with normal hearing in cases of ambiguous stimuli and 19% lower for typical male and female voices. The authors found no significant improvement in voice gender categorization with CI experience. These results emphasize the dissociation between recovery of speech recognition and voice feature perception after cochlear implantation. This large and durable deficit may be related to spectral and temporal degradation induced by CI sound coding, or it may be related to central voice processing deficits.

SU‐E‐J‐122: Time‐Ordered Four Dimensional Cone‐Beam CT

Purpose: Four‐dimensional (4D) cone‐beam CT (CBCT) techniques have been started to use in clinical sites as a tool of image‐guided radiotherapy (IGRT), especially in the treatment of lung tumors. However, those techniques suppose periodic respiratory motion, and there are little approaches to visualize organs which present non‐periodic time‐ordered motion using CBCT imaging techniques. The present study proposes a method to visualize time‐ordered motion including peristaltic motion of gastrointestinal organs and adjacent area. Methods: Projection data sets of clinical patients and digital phantom were reconstructed in this study. Patients' data sets were acquired using the X‐ray Volume Imaging system (XVI, version 4.2) on Synergy linear accelerator system (Elekta, UK) as pre‐treatment CBCT imaging to setup prostate radiotherapy patients with 11.5 cm offset‐located flat panel detector (FPD) unit. An elliptic‐cylindrical digital phantom which contains a moving air sphere of 3 cm diameter was also reconstructed. These projection data sets were reconstructed using our in‐house reconstruction software based on Feldkamp, Davis and Kress (FDK) algorithm. In this study, 180 degrees or less angular ranges of projection data were used to reconstruct CBCT image set of each time phase, and the range moved as time progressed. Results: Reconstructed sagittal images of clinical patients visualized that flatus and stool inside rectum moved with the progress of time. Reconstructed sagittal images of digital phantom with several angular ranges of projection showed that the longitudinal length is getting shorter with shorter range of projection, though a shape of a sphere is getting blurred in vertical direction. Conclusion: The presented method of time‐ordered 4D CBCT reconstruction visualized deformation of intestine and rectum, and motion of flatus and stool, though the method has a trade‐off between temporal resolution improvement and image quality degradation.

A temporal switch model for estimating transcriptional activity in gene expression

Motivation: The analysis and mechanistic modelling of time series gene expression data provided by techniques such as microarrays, NanoString, reverse transcription–polymerase chain reaction and advanced sequencing are invaluable for developing an understanding of the variation in key biological processes. We address this by proposing the estimation of a flexible dynamic model, which decouples temporal synthesis and degradation of mRNA and, hence, allows for transcriptional activity to switch between different states.Results: The model is flexible enough to capture a variety of observed transcriptional dynamics, including oscillatory behaviour, in a way that is compatible with the demands imposed by the quality, time-resolution and quantity of the data. We show that the timing and number of switch events in transcriptional activity can be estimated alongside individual gene mRNA stability with the help of a Bayesian reversible jump Markov chain Monte Carlo algorithm. To demonstrate the methodology, we focus on modelling the wild-type behaviour of a selection of 200 circadian genes of the model plant Arabidopsis thaliana. The results support the idea that using a mechanistic model to identify transcriptional switch points is likely to strongly contribute to efforts in elucidating and understanding key biological processes, such as transcription and degradation.Contact: B.F.Finkenstadt@Warwick.ac.ukSupplementary information: Supplementary data are available at Bioinformatics online.