bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological plasticity of cardiorespiratory function in a eurythermal marine teleost, the longjaw mudsucker,Gillichthys mirabilis
Authors: Jayasundara Nishad , Somero George N.
Published: May 2013

An insufficient supply of oxygen under thermal stress is thought to define thermal optima and tolerance limits in teleost fish. When under thermal stress, cardiac function plays a crucial role in sustaining adequate oxygen supply for respiring tissues. Thus, adaptive phenotypic plasticity of cardiac performance may be critical for modifying thermal limits during temperature acclimation. Here we investigated effects of temperature acclimation on oxygen consumption, cardiac function and blood oxygen carrying capacity of a eurythermal goby fish, Gillichthys mirabilis, acclimated to 9, 19 and 26°C for 4 weeks. Acclimation did not alter resting metabolic rates or heart rates; no compensation of rates was observed at acclimation temperatures. However, under an acute heat ramp, warm-acclimated fish exhibited greater heat tolerance (CTmax=33.3, 37.1 and 38.9°C for 9°C-, 19°C- and 26°C-acclimated fish, respectively) and higher cardiac arrhythmia temperatures compared with 9°C-acclimated fish. Heart rates measured under an acute heat stress every week during 28 days of acclimation suggested that both maximum heart rates and temperature at onset of maximum heart rates changed over time with acclimation. Hemoglobin levels increased with acclimation temperature, from 35 g l−1 in 9°C-acclimated fish to 60–80 g l−1 in 19°C- and 26°C-acclimated fish. Oxygen consumption rates during recovery from acute heat stress showed post-stress elevation in 26°C-acclimated fish. These data, coupled with elevated resting metabolic rates and heart rates at warm temperatures, suggest a high energetic cost associated with warm acclimation in G. mirabilis. Furthermore, acclimatory capacity appears to be optimized at 19°C, a temperature shown by behavioral studies to be close to the species' preferred temperature.
Activity-dependent gene expression in honey bee mushroom bodies in response to orientation flight
Authors: Lutz Claudia C. , Robinson Gene E.
Published: May 2013

The natural history of adult worker honey bees (Apis mellifera) provides an opportunity to study the molecular basis of learning in an ecological context. Foragers must learn to navigate between the hive and floral locations that may be up to miles away. Young pre-foragers prepare for this task by performing orientation flights near the hive, during which they begin to learn navigational cues such as the appearance of the hive, the position of landmarks, and the movement of the sun. Despite well-described spatial learning and navigation behavior, there is currently limited information on the neural basis of insect spatial learning. We found that Egr, an insect homolog of Egr-1, is rapidly and transiently upregulated in the mushroom bodies in response to orientation. This result is the first example of an Egr-1 homolog acting as a learning-related immediate-early gene in an insect and also demonstrates that honey bee orientation uses a molecular mechanism that is known to be involved in many other forms of learning. This transcriptional response occurred both in naïve bees and in foragers induced to re-orient. Further experiments suggest that visual environmental novelty, rather than exercise or memorization of specific visual cues, acts as the stimulus for Egr upregulation. Our results implicate the mushroom bodies in spatial learning and emphasize the deep conservation of Egr-related pathways in experience-dependent plasticity.
Removal of As3+ Using Chitosan–Montmorillonite Composite: Sorptive Equilibrium and Kinetics
Authors: Anjum Ansar , Seth Chand K. , Datta Monika
Published: May 2013

In this study, the sorptive removal of As3+ with promising sorption efficiency up to a very low concentration has been investigated using chitosan–montmorillonite (MMT) composites (in the form of powder and beads). In addition, the recovery of the composite from the sorbent is proposed as well. The sorbent has been observed to show a sorption efficiency of 42.0% from 0.006 μg ml−1 of metal ion. The batch adsorption model was developed to predict the equilibrium adsorption capacity with respect to the pH of As3+ solution, contact time and initial concentration of metal ion. The maximum As3+ sorption capacity of 48.7 mg g−1 (achieved within 10 minutes of contact time) was obtained using chitosan–MMT beads at the pH of drinking water (8.0) at 298 K. The equilibrium sorption data were fitted to the Langmuir and Freundlich adsorption models and the model parameters were evaluated, wherein the Freundlich model shows the most favourable representation of As3+ adsorption behaviour. The biocomposites show comparable high sorption capacity with detection and estimation of As3+ from 0.004 (4.0 ppb) to 100.00 μg ml−1 (100.0 ppm) of aqueous solution. The adsorption kinetics demonstrated intra-particle diffusion as the rate-determining step during the initial phase of adsorption (up to 10 minutes of contact time), which were supported by X-ray diffraction studies; by contrast, chemisorption was found to be the rate-determining step during the later part of adsorption (after 10 minutes of contact time), which were confirmed by Fourier transform infrared spectroscopy-attenuated total reflectance studies. Desorption of As3+ from the sorbents was optimized using potassium dihydrogen phosphate, wherein 0.1 M of the desorbate was found to be an appreciable regenerating agent supporting the reusability of the sorbent up to three cycles, retaining 4402 μg g−1 of the metal ion.
Adsorption of Phenols from Different Solvents on Graphene: Semi-Empirical Quantum Mechanical Calculations
Authors: Húmpola Pablo , Odetti Héctor S. , Albesa Alberto G. , Vicente José L.
Published: May 2013

The adsorption of phenol from aqueous solutions on carbon surfaces is discussed from different theoretical points of view, such as Monte–Carlo simulations, semi-empirical calculations, density functional theory and molecular dynamics. We performed a quantitative analysis of the adsorption of aromatics in general, and phenolic compounds in particular, through semi-empirical quantum mechanical calculations using different approaches. Our results raise doubts that phenol is primarily adsorbed in flat position on the graphene layers, and consequently whether the adsorption forces are controlled by π–π dispersion interactions between the aromatic ring of phenol and the graphene layer structure. Based on the results of quantum mechanical calculations (carried out through various approaches), we conclude that neither surface oxidation nor the presence of a polarizable solvent is consistent with the claim that π–π interactions are dominant in the adsorption of phenolic compounds on graphite.
Global-Local Analysis for a Lateral-Loading Test on a Real RC Frame Structure
Authors: Yue Jian-Guang , Qian Jiang , Lei Tuo , Lu Liang , Lu Xi-Lin
Published: May 2013

In order to study the mechanical behavior and the failure mode of existing RC frame structure, a real three-story RC frame structure including external masonry walls was tested by lateral loading. The global structure exhibited a column-sway collapse mechanism with shear-flexure hinges at the top ends of the columns at the first story. The external wall along the loading direction at the bottom story exceeded its ultimate capacity indicated by a large through-the-wall diagonal crack. A Local-Fine Model (LFM) is presented to capture the global-local nonlinear behavior of the test structure. Based on the damage law of the frame structure, the test structure is divided into linear regions with one-dimensional elements and nonlinear regions with three-dimensional elements in the LFM. All damages are assumed only occurred in the nonlinear regions. Different dimensional elements are coupled by the multi-point constraint equations. The calculated global failure progress, bearing capacity and the local concrete strain agrees closely with the test. The calculated local steel yield progress is in accordance with the test failure progress. Those results indicate the presented LFM can reflect the global behavior and local damages of the structure accurately.
Surrogate Function of Post-Tensioning Cable Forces for Cable-Stayed Bridges
Authors: Hassan M. M. , Nassef A.O. , Damatty A.A. El
Published: May 2013

Inclined stay cables in cable-stayed bridges are post-tensioned in order to counteract the effect of the deck dead load. The evaluation of the post-tensioning forces is tackled in previous literature using either of the iterative unit load method, the force equilibrium method, or by using optimization search methods. All of the above mentioned methods are computationally intensive which hamper their further use in an optimal design algorithm of the bridge. This paper presents a simple surrogate function that can be used to evaluate post-tensioning cable forces in semi-cable stayed bridge under the action of the dead load. The post-tensioning forces for several configurations of the semi-fan cable-stayed bridges are evaluated using genetic algorithms, and are approximated using a simple polynomial function. The developed surrogate functions are used to study the effect of the main span length of the bridge as well as of the pylon height on the distribution and magnitude of the post-tensioning cable forces.
Ultimate Shear Resistance of Perfobond Rib Shear Connectors Based on a Modified Push-Out Test
Authors: Wang Zhenhai , Li Qiao , Zhao Canhui
Published: May 2013

This paper evaluates the ultimate shear resistance(USR) of the perfobond rib shear connector(PRSC) based on a modified push-out test and establishes a new equation for the USR. 33 modified push-out specimens were constructed and tested. The specimens had different perfobond bar diameters, perfobond rib hole diameters, concrete strengthes and transversal rebar quantities. From the test results, influencing factors of the USR such as the ultimate tensile capacity of perfobond bars, the shear stiffness of concrete dowels and the number of transversal rebar were evaluated experimentally. An new equation was developed based on regression analysis for the USR. This equation predicts the USR to within 14% of the experimental results in this test and the push-out tests for PRSC in pylon joint segments.
Using Parameter Expansion Method and Min-Max Approach for the Analytical Investigation of Vibrating Micro-Beams Pre-Deformed by an Electric Field
Authors: Sedighi Hamid M. , Reza Arash , Zare Jamal
Published: May 2013

Two powerful analytical methods called Parameter Expansion method (PEM) and Min-Max approach (MMA) are used to obtain the analytical solution of micro-beams actuated by an electric field. The nonlinear equation of motion has both even and odd nonlinearities. It is shown that two terms in series expansions of PEM are adequate to achieve a highly accurate solution of mentioned system. Comparison of the obtained solutions using numerical method shows the accuracy of the analytical procedures. It is proved that the approximated solutions using PEM are in more agreement with numerical results in comparison with MMA.
A Study on Potential Progressive Collapse Responses of Cable-Stayed Bridges
Authors: Aoki Yukari , Valipour Hamid , Samali Bijan , Saleh Ali
Published: May 2013

In this paper, a finite element (FE) model for a cable-stayed bridge designed according to Australian standards is developed and analysed statically and dynamically with and without geometrical nonlinearities. The dynamic amplification factor ( DAF) and demand-to-capacity ratio ( DCR) in different structural components including cables, towers and the deck are calculated and it is shown that DCR usually remains below one (no material nonlinearity occurs) in the scenarios studied for the bridge under investigation, however, DAF can take values larger than two. Moreover, effects of location, duration and number of cable(s) loss as well as effect of damping level on the progressive collapse resistance of the bridge are studied and importance of each factor on the potential progressive collapse response of the bridgeis investigated.
Plastic Collapse Load of Crown-Hinged Steel Circular Arches: A Theoretical Method
Authors: Spoorenberg R.C. , Snijder H.H. , Hoenderkamp J.C.D.
Published: May 2013

For construction purposes and to avoid detrimental influences of foundation settlements arches are not always made from a single arch-rib but are built by connecting two curvilinear elements at the crown with a hinge. These arches are also known as crown-hinged arches. This paper presents an analytical procedure to approximate the plastic collapse load of circular crown-hinged steel arches. The development of the analytical method employs the lower- and upper bound theorem of plastic theory and the kinematic admissibility requirements. The influence of normal forces on the plastic moment capacity of the steel section is taken into account. The plastic collapse load is obtained by an iterative method as there is a non-linear relationship between the acting loads and the reduction of the plastic moment capacity due to normal forces. Through a comparison with earlier studies and finite element analyses, it is concluded that the proposed iterative method gives good results.
Lateral-Load Behavior Prediction and Pushover Analysis of Reinforced Concrete Columns Including Shear Effects
Authors: Zhang Qin , Gong Jin-Xin , Zhang Yan-Qing
Published: May 2013

A model for predicting the lateral load-deformation response of reinforced concrete (RC) columns subjected to combined bending and shear loads is proposed based on existing analytical models and experimental data from 38 column tests. In this model, the flexural and slip deformations of RC columns are predicted by available models, and the shear deformations are evaluated by the proposed formulas obtained from experimental data analysis and parametric study. The expressions for unloading and reloading stiffnesses, corresponding to different displacements of RC columns, are developed by analyzing the relation between unloading stiffness, reloading stiffness and initial lateral stiffness of columns, respectively, and the expression for calculating equivalent damping ratio according to hysteresis loop area is also provided. Moreover, a single-degree of freedom (SDOF) system is analyzed to illustrate the applications of the proposed model for developing the corresponding capacity curve and demand curve in pushover analysis. Finally, a parametric study is conducted to assess the effect of primary parameters on the seismic performance of columns, such as shear-span ratio, axial load ratio, longitudinal reinforcement ratio and stirrup ratio.
A Hybrid Approach for the Modelling of Complex Systems: Methodologies and Applications
Authors: Christakis Nicholas , Cross Mark , Patel Mayur K. , Tüzün Ugur
Published: May 2013

In this paper the hybrid approach is presented for the modelling of complex systems that involve many interacting components with different physical properties over different spatial and temporal scales. Such systems are difficult to resolve, since they exhibit high levels of uncertainty. We briefly discuss other modelling strategies and their advantages and disadvantages and then a complete description of the mathematical-computational hybrid framework is given. Then, an application from the field of particulate-based engineering processes is presented and the ability of the framework is demonstrated to accurately represent key granular material processes with the aid of information extracted from different scales.
Traffic Flow Anomaly Detection Based on Wavelet Denoising and Support Vector Regression
Authors: Wu Jian , Cui Zhiming , Shi Yujie , Su Dongliang
Published: May 2013

In order to improve the speed and accuracy of traffic flow anomaly detection in real-time traffic system, we proposed an anomaly detection algorithm which is based on wavelet denoising and support vector regression. Firstly, we use wavelet transform to decompose and restructure the sampled data, and then apply support vector regression to data training. By fitting the obtained data, it can achieve dynamic prediction of traffic flow parameters. Through comparing the predictive values with the measured values of traffic flow parameters, we can achieve traffic anomaly detection. Experimental results show that the method proposed in this paper has a higher detection rate under the same false alarm rate.
Antisynchronous spike patterns in dye coupled GABAergic feedback neurons in the brain of the honeybee Apis mellifera
Authors: de Camp Nora Vanessa
Published: May 2013

Intracellular recordings in GABAergic feedback neurons in the mushroom body of the honey bee brain revealed patterns of alternating neural activity. The recorded neurons have been identified via iontophoretic injection of Neurobiotin. The staining of groups of cells indicated dye coupling on the basis of gap junctions. The corresponding spike activity revealed spikes with different but overall comparatively low amplitudes (“spikelets”). The assumption of axo-axonal gap junctions would explain the staining of clusters of feedback neurons, alternating unit activity as well as spikelets with low amplitude. If a neuron in the electrically coupled network fires at a lower than maximal firing rate with respect to the refractory period, it will become more susceptible to laterally incoming spikes of neighbouring feedback neurons. In succession, the respective cell can be fully overtaken by neighbouring spike activity. On the one hand this proposed mechanism could lead to highly synchronous spike activity of a huge number of inhibitory synapses in the mushroom body calyces. On the other hand, the mechanism of laterally spreading activity could act like an amplifier. Additionally, the anatomical properties of Protocerebro Calycal Tract (PCT) feedback neurons could account for a reset function in order to allow for the changing activity profiles of the coupled cells. The laterally incoming potential would run in an antero- and retrograde direction. This could in principle lead to backpropagating inhibition of neighbouring PCT neurons and therefore a reset of one gating cycle. The proposed resulting oscillatory pattern of PCT activity has already been described in the literature and is confirmed by the physiological results, presented here.
Abdominal Migraine in Adults: A Review of Pharmacotherapeutic Options
Authors: Woodruff Ashley E , Cieri Nicole E , Abeles Jennifer , Seyse Stephanie J
Published: May 2013

OBJECTIVE:

To report the case of a 32-year-old woman with abdominal migraine and present a literature review to evaluate abdominal migraine in adults, with particular regard to effective treatment.

CASE SUMMARY:

A 32-year-old African American female presented with recurrent, severe abdominal pain. The patient had several previous admissions with similar symptoms and an extensive gastrointestinal workup in which findings were normal. Attacks of abdominal pain occurred despite treatment with analgesics and antiemetics. She had a family history of migraine headaches. A diagnosis of abdominal migraine was presumed and prophylactic therapy with topiramate 50 mg twice daily relieved the symptoms.

DISCUSSION:

Most published cases of adult abdominal migraine describe females who had a long history of abdominal pain refractory to conventional therapies. The majority of patients had a strong family history of migraine and reported similar episodic abdominal pain. Patients responded to prophylactic migraine therapies, including calcium channel blockers, β-blockers, topiramate, and antihistamines; a few responded to abortive sumatriptan therapy.

CONCLUSIONS:

Abdominal migraine should be considered a possible source of incurable abdominal pain in adults when accompanied by a complete gastrointestinal workup with normal results. We recommend a trial of topiramate as prophylactic therapy if abdominal migraine is the likely source of the pain.
Aflibercept: Newly Approved for the Treatment of Macular Edema Following Central Retinal Vein Occlusion
Authors: Evoy Kirk E , Abel Steven R
Published: May 2013

OBJECTIVE:

To review the pharmacology, efficacy, and safety data available for aflibercept and compare the drug to other therapeutic options for treatment of macular edema following central retinal vein occlusion (CRVO) to determine its likely role in therapy.

DATA SOURCES:

A PubMed search using the terms aflibercept and VEGF trap-eye was conducted to identify initial literature sources. No timeframe was used for exclusion of older trials. All trials referenced were published between January 1995 and December 2012.

STUDY SELECTION AND DATA EXTRACTION:

Trials pertaining to oncologic use were excluded, as were studies conducted in animals and those written in a language other than English. Abstracts of the remaining trials were evaluated for determination of relevance to this review. Additional information sources were obtained via Internet and PubMed following a review of references.

DATA SYNTHESIS:

While previous Phase 1, 2, and 3 trials for other indications (age-related macular degeneration and diabetic macular edema) have shown intravitreal injections of aflibercept to be safe and well tolerated in many patients, preliminary results from the ongoing COPERNICUS and GALILEO trials proved the efficacy of this medication in treating macular edema secondary to CRVO. Of the combined 358 patients studied in COPERNICUS and GALILEO, 56% and 60%, respectively, of the patients receiving aflibercept 2 mg monthly achieved at least a 15-letter improvement in best-corrected visual acuity (BCVA) from baseline over 6 months compared with just 12% and 22% in the control group (p < 0.01 for both). Additionally, in COPERNICUS and GALILEO, patients achieved a 21.3- and 14.7-letter improvement, respectively, in BCVA compared with placebo (p < 0.01 for both).

CONCLUSIONS:

In September 2012, aflibercept became the second vascular endothelial growth factor (VEGF) inhibitor approved for treatment of macular edema secondary to CRVO. While efficacy and safety appear similar to other anti-VEGF treatments, the higher potency, binding affinity, and duration of action make aflibercept an appealing new option.
Gabapentin Therapy of Hiccups
Authors: Thompson Dennis F , Brooks Krista G
Published: May 2013

OBJECTIVE:

To determine whether gabapentin is effective in the treatment of persistent or intractable hiccups.

DATA SOURCES:

A search of MEDLINE (1966-March 2013) using the MeSH search terms gabapentin, hiccups, and hiccups/drug therapy was performed. Additional databases searched included Web of Science (1945-March 2013) and International Pharmaceutical Abstracts (1970-March 2013) using the text words gabapentin and hiccups. Bibliographies of relevant articles were reviewed for additional citations.

STUDY SELECTION AND DATA EXTRACTION:

All data sources were considered for inclusion. Preference was given for articles written in English, although one abstract in German was used.

DATA SYNTHESIS:

Because of the low incidence of persistent or intractable hiccups, few if any controlled clinical trials are conducted on the efficacy of drug treatment. Therefore, most of the data involve case reports or case series. We evaluated 17 case reports and 2 case series involving gabapentin therapy for persistent or intractable hiccups. Therapeutic outcomes with gabapentin were positive in all cases, with temporal evidence suggesting an effect, but outcomes often were obscured by combination therapy and comorbidities in some cases. Case reports suggest that gabapentin might be useful as a second-line agent in patients undergoing stroke rehabilitation or in the palliative care setting where chlorpromazine adverse effects are undesirable. Gabapentin was very well tolerated, with only a few minor adverse effects.

CONCLUSIONS:

Gabapentin has a similar body of evidence as other pharmacotherapeutic agents used to treat hiccups. Gabapentin is well tolerated and should be considered as a second-line agent in selected patients.
Demystifying the dendralenes
Authors: Mackay Emily G. , Sherburn Michael S.
Published: May 2013

We present herein an overview of our ongoing studies with dendralenes. The first synthetic routes to this fundamental family of compounds have revealed long-hidden secrets in hydrocarbon chemistry and set the scene for synthetic and materials chemistry applications.
Investigating interrelations in visual arts education: Aesthetic enquiry, possibility thinking and creativity
Authors: Pavlou Victoria
Published: May 2013

Visual arts education can be an important and powerful field of learning for children. This article explores interrelations between the study of artworks and the development of creativity in children’s thinking and art-making. Starting from the premise that engagement with artworks
does not automatically release children’s imaginative capacities, the article discusses how an aesthetic mode of enquiry can support children’s artviewing and enable the development of possibility thinking; the ability to make connections, to think differently and envisage new
possibilities. Aesthetic enquiry can enable children to actively engage in taking their ideas further, exploring options and employing critical reflection. Providing children with opportunities to materialize their ideas after viewing an artwork, set the prerequisitions for innovative solutions
and the development of creativity. These interrelations between artviewing and art-making are argued theoretically and explored empirically through a small scale exploratory study with 7–8 year olds.
Objective Rhythmic Performance Evaluation Tool (O.R.P.E.T.): A numerical method to evaluate the accuracy of a musical performance
Authors: Vila Antonio Tudurí , Cifre Bartomeu Serra , Llabrés Bartomeu Mut
Published: May 2013

Recent developments in Information Technologies (IT) have given many powerful tools to the field of musical education, which have in turn provided increased pedagogic services to the musical education professionals. This article presents the results of the development of a computer
tool that using musical material in MIDI format and from that material extracts the discrete histogram of occurrence of the different note durations at low level. To evaluate these note length histograms, the authors have also developed a mathematical model to numerically evaluate the rhythmic
‘correctness’ of various performances of the same piano piece (which can be applied to all instrumental reproductions that generate MIDI format material) and compare it to a performance considered as the ‘correct performance’. This method can be used as an additional
technological tool for self-learning for Music Schools and Conservatories to allow the students to check the rhythmic correctness of their own performances. It also could be used as an objective and official evaluation tool for different performances of a musical piece compared with a performance
considered as the ‘correct performance’; for example in a test, exam, entrance exam or in public competitions. In general, the method presented in this article can be used as a technological tool that will support the learning process of piano students.
Mechanistic Evaluation of the Effect of WMA Additives on Wettability and Moisture Susceptibility Properties of Asphalt Mixes
Authors: Ghabchi Rouzbeh , Singh Dharamveer , Zaman Musharraf , Tian Qingyan
Published: May 2013

This study used a mechanistic framework (i.e., surface free energy) to evaluate the moisture susceptibility of warm mix asphalt (WMA) with three different WMA additives, namely, Sasobit, Advera, and Evotherm. The surface free energy (SFE) components of modified PG64-22 asphalt binder with different percentages of WMA additives and selected aggregates were measured in the laboratory. The wettability, the work of adhesion, the work of debonding, and energy ratios were estimated in order to assess the moisture-induced damage potential of combinations of modified asphalt binders and different aggregates. The results indicate that Sasobit and Advera are able to reduce the moisture susceptibility potential of the mixes, but their use is not recommended with highly acidic aggregates such as granite. Evotherm resulted in the highest increases in wettability, total surface free energy, and increased work of adhesion and a reduction in the work of debonding, resulting in a better possible aggregate coating with asphalt binder and lower moisture susceptibility with all types of tested aggregates relative to those of other WMA additives. Furthermore, tensile strength ratio (TSR) tests were conducted on Advera and Evotherm-modified and neat (unmodified) asphalt mixes, and the results were compared with those from the SFE test. It was found that the SFE approach is a better indicator of moisture susceptibility than the traditional TSR test. The findings of the present study would help the highway engineers and agencies to better understand the moisture damage potential of flexible pavements constructed with WMA technologies.
Heat Treating of a 718Plus Superalloy
Authors: Villalón Néstor O. , Covarrubias Octavio , Colás Rafael
Published: May 2013

Hot rolled rings made from nickel-based superalloys are used for the manufacture of rotating components in jet engines and land-based turbines. Contoured rings are attractive to manufacturers because they can simplify and improve manufacturing operations by reducing machining times and, in some cases, eliminating welding operations. ATI 718Plus is a nickel-based superalloy designed to achieve high strength and thermal stability at elevated temperatures while exhibiting good formability during forging operations, characteristics that making it a suitable alloy for the manufacture of contoured rings. This work presents the results of a series of solution and precipitation heat treatments of rings made from ATI 718Plus with the goal of optimizing their processing and mechanical behavior. Microstructural characteristics and mechanical properties are reported, including the results of tensile tests conducted at room temperature and at high temperature and of hardness and stress-rupture testing. The results of this work were implemented at a local factory to ensure the required mechanical properties of heat-treated parts.
Neural Context Reinstatement Predicts Memory Misattribution
Authors: Gershman Samuel J. , Schapiro Anna C. , Hupbach Almut , Norman Kenneth A.
Published: May 2013

What causes new information to be mistakenly attributed to an old experience? Some theories predict that reinstating the context of a prior experience allows new information to be bound to that context, leading to source memory confusion. To examine this prediction, we had human participants study two lists of items (visual objects) on separate days while undergoing functional magnetic resonance imaging. List 1 items were accompanied by a stream of scene images during the intertrial interval, but list 2 items were not. As in prior work by Hupbach et al. (2009), we observed an asymmetric pattern of misattributions on a subsequent source memory test: participants showed a strong tendency to misattribute list 2 items to list 1 but not vice versa. We hypothesized that these memory errors were due to participants reinstating the list 1 context during list 2. To test this hypothesis, we used a pattern classifier to measure scene-related neural activity during list 2 study. Because scenes were visually present during list 1 but not list 2, scene-related activity during list 2 study can be used as a time-varying neural indicator of how much participants were reinstating the list 1 context during list 2 study. In keeping with our hypothesis, we found that prestimulus scene activation during the study of list 2 items was significantly higher for items subsequently misattributed to list 1 than for items subsequently correctly attributed to list 2. We conclude by discussing how these findings relate to theories of memory reconsolidation.
Ligand for Translocator Protein Reverses Pathology in a Mouse Model of Alzheimer's Disease
Authors: Barron Anna M. , Garcia-Segura Luis M. , Caruso Donatella , Jayaraman Anusha , Lee Joo-Won , Melcangi Roberto C. , Pike Christian J.
Published: May 2013

Ligands of the translocator protein (TSPO) elicit pleiotropic neuroprotective effects that represent emerging treatment strategies for several neurodegenerative conditions. To investigate the potential of TSPO as a therapeutic target for Alzheimer's disease (AD), the current study assessed the effects of the TSPO ligand Ro5-4864 on the development of neuropathology in 3xTgAD mice. The effects of the TSPO ligand on neurosteroidogenesis and AD-related neuropathology, including β-amyloid accumulation, gliosis, and behavioral impairment, were examined under both early intervention (7-month-old young-adult male mice with low pathology) and treatment (24-month-old, aged male mice with advanced neuropathology) conditions. Ro5-4864 treatment not only effectively attenuated development of neuropathology and behavioral impairment in young-adult mice but also reversed these indices in aged 3xTgAD mice. Reduced levels of soluble β-amyloid were also observed by the combination of TSPO ligands Ro5-4864 and PK11195 in nontransgenic mice. These findings suggest that TSPO is a promising target for the development of pleiotropic treatment strategies for the management of AD.
Most Vesicles in a Central Nerve Terminal Participate in Recycling
Authors: Xue Lei , Sheng Jiansong , Wu Xin-Sheng , Wu Wei , Luo Fujun , Shin Wonchul , Chiang Hsueh-Cheng , Wu Ling-Gang
Published: May 2013

Studies over the last decade using FM dyes to label vesicles at many terminals, including the calyx-type nerve terminal, led to a well accepted “principle” that only a small fraction of vesicles (∼5–20%) participate in recycling under physiological conditions. This principle imposes a large challenge in maintaining synaptic transmission during repetitive firing, because the small recycling pool may limit the number of available vesicles for release and nerve terminals would have to distinguish the recycling pool from the reserve pool and keep reserve pool vesicles from being used. By recording the presynaptic capacitance changes and the postsynaptic EPSC at rat calyx of Held synapses in the absence or presence of transmitter glutamate in nerve terminals, we developed a new method to count functional recycling vesicles. We found that essentially all vesicles in calyces participated in recycling, challenging the small-recycling-pool principle established by FM dye labeling. Nerve terminals may use all available vesicles to maximize their ability in maintaining synaptic transmission during repetitive firing.
Spinal Premotor Interneurons Mediate Dynamic and Static Motor Commands for Precision Grip in Monkeys
Authors: Takei Tomohiko , Seki Kazuhiko
Published: May 2013

The extent of spinal interneuron (IN) contribution to dexterous hand movements is unclear. Here, we studied the response patterns and force relationships of spinal premotor INs (PreM-INs) in three awake, behaving monkeys performing a precision grip task. We recorded activity from the cervical spinal cord (C5–T1) simultaneously with electromyographic (EMG) activity from hand and arm muscles during the task. Spike-triggered averaging of EMGs showed that 25 PreM-INs had postspike effects on EMG activity. Most PreM-INs (23/25) displayed movement-related firing rate modulations: 11 had phasic followed by tonic facilitation (p+t+); 4 were pure phasic; 4 were pure tonic; and 4 were deactivated, while their target muscles consistently had p+t+ activity (65/66 muscles). PreM-IN phasic activity started earlier than target muscle activity (49 ± 81.4 ms, mean ± SD), and the peak amplitude was correlated with the peak amplitude of the rate of change of grip force (4/17,p< 0.05), suggesting that they contributed to force initiation. In contrast, PreM-IN tonic activity started at almost the same time as the target muscle activity and the mean firing rate was correlated with the mean grip force during the hold period (4/15,p< 0.05), suggesting that they contributed to force maintenance. These results indicated that the neural pathway mediated by the spinal PreM-INs makes a significant contribution to the control of precision grip in primates.
The Synchronous Activity of Lateral Habenular Neurons Is Essential for Regulating Hippocampal Theta Oscillation
Authors: Aizawa Hidenori , Yanagihara Shin , Kobayashi Megumi , Niisato Kazue , Takekawa Takashi , Harukuni Rie , McHugh Thomas J. , Fukai Tomoki , Isomura Yoshikazu , Okamoto Hitoshi
Published: May 2013

Lateral habenula (LHb) has attracted growing interest as a regulator of serotonergic and dopaminergic neurons in the CNS. However, it remains unclear how the LHb modulates brain states in animals. To identify the neural substrates that are under the influence of LHb regulation, we examined the effects of rat LHb lesions on the hippocampal oscillatory activity associated with the transition of brain states. Our results showed that the LHb lesion shortened the theta activity duration both in anesthetized and sleeping rats. Furthermore, this inhibitory effect of LHb lesion on theta maintenance depended upon an intact serotonergic median raphe, suggesting that LHb activity plays an essential role in maintaining hippocampal theta oscillation via the serotonergic raphe. Multiunit recording of sleeping rats further revealed that firing of LHb neurons showed significant phase-locking activity at each theta oscillation cycle in the hippocampus. LHb neurons showing activity that was coordinated with that of the hippocampal theta were localized in the medial LHb division, which receives afferents from the diagonal band of Broca (DBB), a pacemaker region for the hippocampal theta oscillation. Thus, our findings indicate that the DBB may pace not only the hippocampus, but also the LHb, during rapid eye movement sleep. Since serotonin is known to negatively regulate theta oscillation in the hippocampus, phase-locking activity of the LHb neurons may act, under the influence of the DBB, to maintain the hippocampal theta oscillation by modulating the activity of serotonergic neurons.
Evidence for Encoding versus Retrieval Scheduling in the Hippocampus by Theta Phase and Acetylcholine
Authors: Douchamps Vincent , Jeewajee Ali , Blundell Pam , Burgess Neil , Lever Colin
Published: May 2013

The formation of new memories requires new information to be encoded in the face of proactive interference from the past. Two solutions have been proposed for hippocampal region CA1: (1) acetylcholine, released in novelty, selectively suppresses excitatory projections to CA1 from CA3 (mediating the products of retrieval), while sparing entorhinal inputs (mediating novel sensory information) and (2) encoding preferentially occurs at the pyramidal-layer theta peak, coincident with input from entorhinal cortex, and retrieval occurs at the trough, coincident with input from CA3, consistent with theta phase-dependent synaptic plasticity. We examined three predictions of these models: (1) in novel environments, the preferred theta phase of CA1 place cell firing should shift closer to the CA1 pyramidal-layer theta peak, shifting the encoding-retrieval balance toward encoding; (2) the encoding-related shift in novel environments should be disrupted by cholinergic antagonism; and (3) in familiar environments, cholinergic antagonism should shift the preferred theta firing phase closer to the theta trough, shifting the encoding-retrieval balance even further toward retrieval. We tested these predictions by recording from CA1 pyramidal cells in freely moving rats as they foraged in open field environments under the influence of scopolamine (an amnestic cholinergic antagonist) or vehicle (saline). Results confirmed all three predictions, supporting both the theta phase and cholinergic models of encoding versus retrieval dynamics. Also consistent with cholinergic enhancement of encoding, scopolamine attenuated the formation of distinct spatial representations in a new environment, reducing the extent of place cell “remapping.”
Novelty and Anxiolytic Drugs Dissociate Two Components of Hippocampal Theta in Behaving Rats
Authors: Wells Christine E. , Amos Doran P. , Jeewajee Ali , Douchamps Vincent , Rodgers John , O'Keefe John , Burgess Neil , Lever Colin
Published: May 2013

Hippocampal processing is strongly implicated in both spatial cognition and anxiety and is temporally organized by the theta rhythm. However, there has been little attempt to understand how each type of processing relates to the other in behaving animals, despite their common substrate. In freely moving rats, there is a broadly linear relationship between hippocampal theta frequency and running speed over the normal range of speeds used during foraging. A recent model predicts that spatial-translation-related and arousal/anxiety-related mechanisms of hippocampal theta generation underlie dissociable aspects of the theta frequency–running speed relationship (the slope and intercept, respectively). Here we provide the first confirmatory evidence: environmental novelty decreases slope, whereas anxiolytic drugs reduce intercept. Variation in slope predicted changes in spatial representation by CA1 place cells and novelty-responsive behavior. Variation in intercept predicted anxiety-like behavior. Our findings isolate and doubly dissociate two components of theta generation that operate in parallel in behaving animals and link them to anxiolytic drug action, novelty, and the metric for self-motion.
State-Dependent Contribution of the Hyperpolarization-Activated Na+/K+and Persistent Na+Currents to Respiratory RhythmogenesisIn Vivo
Authors: Montandon Gaspard , Horner Richard L.
Published: May 2013

How rhythms are generated by neuronal networks is fundamental to understand rhythmic behaviors such as respiration, locomotion, and mastication. Respiratory rhythm is generated by the preBötzinger complex (preBötC), an anatomically and functionally discrete population of brainstem neurons, central and necessary for respiratory rhythm. In specificin vitroconditions, preBötC neurons depend on voltage-dependent inward currents to generate respiratory rhythm. In the mature and intact organism, where preBötC neurons are deeply embedded in the respiratory network, the contribution of ionic currents to respiratory rhythm is unclear. We propose that a set of ionic currents plays a key role in generating respiratory rhythm in the mature organismin vivo. By microperfusing ionic current blockers into the preBötC of adult rats, we identify the hyperpolarization-activated cation current as a critical component of the mechanism promoting respiratory rhythm, and that this current, in combination with the persistent sodium current, is essential to respiratory rhythmin vivo. Importantly, both currents contribute to rhythmic activity in states of anesthesia, quiet wakefulness, and sleep, but not when the organism is engaged in active behaviors. These data show that a set of ionic currents at the preBötC imparts the network with rhythmicity in reduced states of arousal, although the network can override their contribution to adjust its activity for nonrhythmic behaviors in active wakefulness.
Incentive Memory: Evidence the Basolateral Amygdala Encodes and the Insular Cortex Retrieves Outcome Values to Guide Choice between Goal-Directed Actions
Authors: Parkes Shauna L. , Balleine Bernard W.
Published: May 2013

Choice between goal-directed actions is determined by the relative value of their consequences. Such values are encoded during incentive learning and later retrieved to guide performance. Although the basolateral amygdala (BLA) and the gustatory region of insular cortex (IC) have been implicated in these processes, their relative contribution is still a matter of debate. Here we assessed whether these structures interact during incentive learning and retrieval to guide choice. In these experiments, rats were trained on two actions for distinct outcomes after which one of the two outcomes was devalued by specific satiety immediately before a choice extinction test. We first confirmed that, relative to appropriate controls, outcome devaluation recruited both the BLA and IC based on activation of the immediate early geneArc; however, we found that infusion of the NMDAr antagonist ifenprodil into the BLA only abolished outcome devaluation when given before devaluation. In contrast, ifenprodil infusion into the IC was effective whether made before devaluation or test. We hypothesized that the BLA encodes and the IC retrieves incentive value for choice and, to test this, developed a novel sequential disconnection procedure. Blocking NMDAr activation unilaterally in the BLA before devaluation and then contralaterally in the IC before test abolished selective devaluation. In contrast, reversing the order of these infusions left devaluation intact. These results confirm that the BLA and IC form a circuit mediating the encoding and retrieval of outcome values, with the BLA encoding and the IC retrieving such values to guide choice.
Genetic Reconstruction of Dopamine D1 Receptor Signaling in the Nucleus Accumbens Facilitates Natural and Drug Reward Responses
Authors: Gore Bryan B. , Zweifel Larry S.
Published: May 2013

The dopamine D1 receptor (D1R) facilitates reward acquisition and its alteration leads to profound learning deficits. However, its minimal functional circuit requirement is unknown. Using conditional reconstruction of functional D1R signaling in D1R knock-out mice, we define distinct requirements of D1R in subregions of the nucleus accumbens (NAc) for specific dimensions of reward. We demonstrate that D1R expression in the core region of the NAc (NAcCore), but not the shell (NAcShell), enhances selectively a unique form of pavlovian conditioned approach and mediates D1R-dependent cocaine sensitization. However, D1R expression in either the NAcCoreor the NAcShellimproves instrumental responding for reward. In contrast, neither NAcCorenor NAcShellD1R is sufficient to promote motivation to work for reward in a progressive ratio task or for motor learning. These results highlight dissociated circuit requirements of D1R for dopamine-dependent behaviors.
Strengthened Effective Connectivity Underlies Transfer of Working Memory Training to Tests of Short-Term Memory and Attention
Authors: Kundu Bornali , Sutterer David W. , Emrich Stephen M. , Postle Bradley R.
Published: May 2013

Although long considered a natively endowed and fixed trait, working memory (WM) ability has recently been shown to improve with intensive training. What remains controversial and poorly understood, however, are the neural bases of these training effects and the extent to which WM training gains transfer to other cognitive tasks. Here we present evidence from human electrophysiology (EEG) and simultaneous transcranial magnetic stimulation and EEG that the transfer of WM training to other cognitive tasks is supported by changes in task-related effective connectivity in frontoparietal and parieto-occipital networks that are engaged by both the trained and transfer tasks. One consequence of this effect is greater efficiency of stimulus processing, as evidenced by changes in EEG indices of individual differences in short-term memory capacity and in visual search performance. Transfer to search-related activity provides evidence that something more fundamental than task-specific strategy or stimulus-specific representations has been learned. Furthermore, these patterns of training and transfer highlight the role of common neural systems in determining individual differences in aspects of visuospatial cognition.