Showing papers by "University of Texas at Dallas published in 2011"

Toward defining the preclinical stages of Alzheimer's disease: Recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease

Abstract: The pathophysiological process of Alzheimer's disease (AD) is thought to begin many years before the diagnosis of AD dementia. This long "preclinical" phase of AD would provide a critical opportunity for therapeutic intervention; however, we need to further elucidate the link between the pathological cascade of AD and the emergence of clinical symptoms. The National Institute on Aging and the Alzheimer's Association convened an international workgroup to review the biomarker, epidemiological, and neuropsychological evidence, and to develop recommendations to determine the factors which best predict the risk of progression from "normal" cognition to mild cognitive impairment and AD dementia. We propose a conceptual framework and operational research criteria, based on the prevailing scientific evidence to date, to test and refine these models with longitudinal clinical research studies. These recommendations are solely intended for research purposes and do not have any clinical implications at this time. It is hoped that these recommendations will provide a common rubric to advance the study of preclinical AD, and ultimately, aid the field in moving toward earlier intervention at a stage of AD when some disease-modifying therapies may be most efficacious.

Carbon-based Supercapacitors Produced by Activation of Graphene

Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

Happy People Live Longer: Subjective Well‐Being Contributes to Health and Longevity

Abstract: Seven types of evidence are reviewed that indicate that high subjective wellbeing (such as life satisfaction, absence of negative emotions, optimism, and positive emotions) causes better health and longevity For example, prospective longitudinal studies of normal populations provide evidence that various types of subjective well-being such as positive affect predict health and longevity, controlling for health and socioeconomic status at baseline Combined with experimental human and animal research, as well as naturalistic studies of changes of subjective well-being and physiological processes over time, the case that subjective well-being influences health and longevity in healthy populations is compelling However, the claim that subjective well-being lengthens the lives of those with certain diseases such as cancer remains controversial Positive feelings predict longevity and health beyond negative feelings However, intensely aroused or manic positive affect may be detrimental to health Issues such as causality, effect size, types of subjective well-being, and statistical controls are discussed

Large-Area Graphene Single Crystals Grown by Low-Pressure Chemical Vapor Deposition of Methane on Copper

Abstract: Graphene single crystals with dimensions of up to 0.5 mm on a side were grown by low-pressure chemical vapor deposition in copper-foil enclosures using methane as a precursor. Low-energy electron microscopy analysis showed that the large graphene domains had a single crystallographic orientation, with an occasional domain having two orientations. Raman spectroscopy revealed the graphene single crystals to be uniform monolayers with a low D-band intensity. The electron mobility of graphene films extracted from field-effect transistor measurements was found to be higher than 4000 cm2 V−1 s−1 at room temperature.

A Baseline for the Multivariate Comparison of Resting-State Networks

Abstract: As the size of functional and structural MRI datasets expands, it becomes increasingly important to establish a baseline from which diagnostic relevance may be determined, a processing strategy that efficiently prepares data for analysis, and a statistical approach that identifies important effects in a manner that is both robust and reproducible. In this paper, we introduce a multivariate analytic approach that optimizes sensitivity and reduces unnecessary testing. We demonstrate the utility of this mega-analytic approach by identifying the effects of age and gender on the resting-state networks (RSNs) of 603 healthy adolescents and adults (mean age: 23.4 years, range: 12–71 years). Data were collected on the same scanner, preprocessed using an automated analysis pipeline based in SPM, and studied using group independent component analysis. RSNs were identified and evaluated in terms of three primary outcome measures: time course spectral power, spatial map intensity, and functional network connectivity. Results revealed robust effects of age on all three outcome measures, largely indicating decreases in network coherence and connectivity with increasing age. Gender effects were of smaller magnitude but suggested stronger intra-network connectivity in females and more inter-network connectivity in males, particularly with regard to sensorimotor networks. These findings, along with the analysis approach and statistical framework described here, provide a useful baseline for future investigations of brain networks in health and disease.

Nonfinancial Disclosure and Analyst Forecast Accuracy: International Evidence on Corporate Social Responsibility Disclosure

Abstract: We examine the relationship between disclosure of nonfinancial information and analyst forecast accuracy using firm-level data from 31 countries. We use the issuance of standalone corporate social responsibility (CSR) reports to proxy for disclosure of nonfinancial information. We find that the issuance of standalone CSR reports is associated with lower analyst forecast error. This relationship is stronger in countries that are more stakeholder-oriented — i.e., in countries where CSR performance is more likely to affect firm financial performance. The relationship is also stronger for firms and countries with more opaque financial disclosure, suggesting that issuance of standalone CSR reports plays a role complementary to financial disclosure. These results hold after we control for various factors related to firm financial transparency and other potentially confounding institutional factors. Collectively, our findings have important implications for academics and practitioners in understanding the function of CSR disclosure in financial markets.

The effect of chemical residues on the physical and electrical properties of chemical vapor deposited graphene transferred to SiO2

Abstract: The effects of residues introduced during the transfer of chemical vapor deposited graphene from a Cu substrate to an insulating (SiO2) substrate on the physical and electrical of the transferred graphene are studied X-ray photoelectron spectroscopy and atomic force microscopy show that this residue can be substantially reduced by annealing in vacuum The impact of the removal of poly(methyl methacrylate) residue on the electrical properties of graphene field effect devices is demonstrated, including a nearly 2 × increase in average mobility from 1400 to 2700 cm2/Vs The electrical results are compared with graphene doping measurements by Raman spectroscopy

The Role of Oxygen during Thermal Reduction of Graphene Oxide Studied by Infrared Absorption Spectroscopy

Abstract: Understanding the thermal reduction of graphene oxide (GO) is important for graphene exfoliation, and chemical and morphological modifications. In this process, the role of trapped water and the evolution of oxygen during annealing are still not well-understood. To unravel the complex mechanisms leading to the removal of oxygen in reduced GO, we have performed in situ transmission infrared absorption spectroscopy measurements of GO films upon thermal annealing at 60–850 °C in vacuum (10–3–10–4 Torr). Using cluster-based first-principles calculations, epoxides, ethers (pyrans and furans), hydroxyls, carboxyls, lactols, and various types of ketones and their possible derivatives have been identified from the spectroscopic data. Furthermore, the interactions between randomly arranged nearby oxygen species are found to affect the spectral response (red and blue shifts) and the overall chemistry during annealing. For instance, the initial composition of oxygen species (relative amounts and types of species, su...

Automatic Summarization

Abstract: It has now been 50 years since the publication of Luhn’s seminal paper on automatic summarization. During these years the practical need for automatic summarization has become increasingly urgent and numerous papers have been published on the topic. As a result, it has become harder to find a single reference that gives an overview of past efforts or a complete view of summarization tasks and necessary system components. This article attempts to fill this void by providing a comprehensive overview of research in summarization, including the more traditional efforts in sentence extraction as well as the most novel recent approaches for determining important content, for domain and genre specific summarization and for evaluation of summarization. We also discuss the challenges that remain open, in particular the need for language generation and deeper semantic understanding of language that would be necessary for future advances in the field. We would like to thank the anonymous reviewers, our students and Noemie Elhadad, Hongyan Jing, Julia Hirschberg, Annie Louis, Smaranda Muresan and Dragomir Radev for their helpful feedback. This paper was supported in part by the U.S. National Science Foundation (NSF) under IIS-05-34871 and CAREER 09-53445. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. Full text available at: http://dx.doi.org/10.1561/1500000015

Reversing pathological neural activity using targeted plasticity

Abstract: Neuronal plasticity, the process by which the human brain changes as a result of experience, is thought to be the source of several chronic neurological conditions, including tinnitus. Using a rodent model for noise-induced tinnitus, Engineer et al. find that reversing neural plasticity induced by the tinnitus can correct perceptual impairment. Repeatedly pairing tones with a brief stimulation of the vagus nerve sharpens auditory neuron tuning and eliminates the physiological and behavioural signs of tinnitus. This proof of principle suggests that simply restoring normal neural activity to circuits that have been pathologically modified could provide a benefit in conditions involving aberrant neural plasticity. Neuronal plasticity is thought to be the source of several chronic neurological conditions, including tinnitus. Using a rodent model for noise-induced tinnitus, this study finds that reversing neural plasticity induced by the tinnitus can correct perceptual impairments caused by the ailment. Pairing tones with stimulation of the vagus nerve sharpened auditory neuron tuning and eliminated the physiological as well as behavioural correlates of the tinnitus. This proof of principle suggests that simply restoring normal neural activity to circuits that have been pathologically modified could provide a benefit in those ailments involving aberrant neural plasticity. Brain changes in response to nerve damage or cochlear trauma can generate pathological neural activity that is believed to be responsible for many types of chronic pain and tinnitus1,2,3. Several studies have reported that the severity of chronic pain and tinnitus is correlated with the degree of map reorganization in somatosensory and auditory cortex, respectively1,4. Direct electrical or transcranial magnetic stimulation of sensory cortex can temporarily disrupt these phantom sensations5. However, there is as yet no direct evidence for a causal role of plasticity in the generation of pain or tinnitus. Here we report evidence that reversing the brain changes responsible can eliminate the perceptual impairment in an animal model of noise-induced tinnitus. Exposure to intense noise degrades the frequency tuning of auditory cortex neurons and increases cortical synchronization. Repeatedly pairing tones with brief pulses of vagus nerve stimulation completely eliminated the physiological and behavioural correlates of tinnitus in noise-exposed rats. These improvements persisted for weeks after the end of therapy. This method for restoring neural activity to normal may be applicable to a variety of neurological disorders.

Torsional Carbon Nanotube Artificial Muscles

Abstract: Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

Charged-particle multiplicities in pp interactions measured with the ATLAS detector at the LHC

Abstract: Measurements are presented from proton-proton collisions at centre-of-mass energies of root s = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections. The results are compared to each other and to various Monte Carlo (MC) models, including a new AMBT1 pythia6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the MC models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with p(T) > 100 MeV, is measured to be 3.483 +/- 0.009 (stat) +/- 0.106 (syst) at root s = 0.9 TeV and 5.630 +/- 0.003 (stat) +/- 0.169 (syst) at root s = 7 TeV.

Perspective of Recent Progress in Immobilization of Enzymes

Abstract: The commercial application of biocatalysts depends on the development of effective methods of immobilization. The immobilization of enzymes greatly increases the stability of enzymes and eases the burden of enzyme cost and thus, is widely pursued for efficient, selective, and environmentally friendly catalysis. This brief perspective focuses on recent development in the area of enzyme immobilization in porous materials. Recent work regarding the immobilization of enzymes in inorganic mesoporous materials as well as the modifications to those materials is summarized in this paper. The configuration of supported enzyme as membranes and fibers may facilitate their application in areas that require a biocatalytic process. Enzymes immobilized in or on fibrous membranes provide high surface area for high throughput biocatalysis. These membrane bioreactors also allow for biotransformations to be carried out within a continuous flow process while maintaining enzyme stability under operating conditions as a result...

Synthesis of Pd−Pt Bimetallic Nanocrystals with a Concave Structure through a Bromide-Induced Galvanic Replacement Reaction

Abstract: This article describes a systematic study of the galvanic replacement reaction between PtCl62− ions and Pd nanocrystals with different shapes, including cubes, cuboctahedrons, and octahedrons. It was found that Br− ions played an important role in initiating, facilitating, and directing the replacement reaction. The presence of Br− ions led to the selective initiation of galvanic replacement from the {100} facets of Pd nanocrystals, likely due to the preferential adsorption of Br− ions on this crystallographic plane. The site-selective galvanic replacement resulted in the formation of Pd−Pt bimetallic nanocrystals with a concave structure owing to simultaneous dissolution of Pd atoms from the {100} facets and deposition of the resultant Pt atoms on the {111} facets. The Pd−Pt concave nanocubes with different weight percentages of Pt at 3.4, 10.4, 19.9, and 34.4 were also evaluated as electrocatalysts for the oxygen reduction reaction (ORR). Significantly, the sample with a 3.4 wt.% of Pt exhibited the lar...

Domestic versus transnational terrorism: Data, decomposition, and dynamics

Abstract: This article devises a method to separate the Global Terrorism Database (GTD) into transnational and domestic terrorist incidents. This decomposition is essential for the understanding of some terrorism phenomena when the two types of terrorism are hypothesized to have different impacts. For example, transnational terrorism may have a greater adverse effect than domestic terrorism on economic growth. Moreover, the causes of the two types of terrorism may differ. Once the data are separated, we apply a calibration method to address some issues with GTD data - namely, the missing data for 1993 and different coding procedures used before 1998. In particular, we calibrate the GTD transnational terrorist incidents to ITERATE transnational terrorist incidents to address GTD's undercounting of incidents in much of the 1970s and its overcounting of incidents in much of the 1990s. Given our assumption that analogous errors characterize domestic terrorist events in GTD, we apply the same calibrations to adjust GTD domestic incidents. The second part of the article investigates the dynamic aspects of GTD domestic and transnational terrorist incidents, based on the calibrated data. Contemporaneous and lagged cross-correlations for the two types of terrorist incidents are computed for component time series involving casualties, deaths, assassinations, bombings, and armed attacks. We find a large cross-correlation between domestic and transnational terrorist incidents that persists over a number of periods. A key finding is that shocks to domestic terrorism result in persistent effects on transnational terrorism; however, the reverse is not true. This finding suggests that domestic terrorism can spill over to transnational terrorism, so that prime-target countries cannot ignore domestic terrorism abroad and may need to assist in curbing this homegrown terrorism.

Luminescent Gold Nanoparticles with Efficient Renal Clearance

Abstract: Developing functional nanomaterials with efficient renal clearance is of fundamental importance to their in vivo biomedical applications.[1] Ideal nanomaterial based contrast agents should be effectively cleared out of the body, have little accumulation in organs and show minimum interference with other diagnostic tests.[1c, 1e, 2] While significant progress has been made toward the creation of fluorescent quantum dots with efficient renal clearance,[2] in vivo applications of noble metal nanoparticles (NPs), another promising nanomedicine in biomedical imaging, drug delivery, antibacterial and photothermal therapy,[3] are still severely hampered by their slow renal clearance and high nonspecific accumulations in the reticuloendothelial system (RES) organs (e.g. liver, spleen) after systematic administration.[4] Although NPs with hydrodynamic diameter (HD) smaller than 10 nm are generally considered being stealthy to the RES organs, they are still often found in the liver.[2a] For example, nearly ~50% of 1.4 nm gold NPs (AuNPs) were found in the liver and only ~9% of them can be excreted into urine in 24 hours after intravenous (IV) injection.[4b] Therefore, developing metal NPs with efficient renal clearance and fundamental understanding of key factors in renal clearance are highly desirable.

Classification and Novel Class Detection in Concept-Drifting Data Streams under Time Constraints

Abstract: Most existing data stream classification techniques ignore one important aspect of stream data: arrival of a novel class. We address this issue and propose a data stream classification technique that integrates a novel class detection mechanism into traditional classifiers, enabling automatic detection of novel classes before the true labels of the novel class instances arrive. Novel class detection problem becomes more challenging in the presence of concept-drift, when the underlying data distributions evolve in streams. In order to determine whether an instance belongs to a novel class, the classification model sometimes needs to wait for more test instances to discover similarities among those instances. A maximum allowable wait time Tc is imposed as a time constraint to classify a test instance. Furthermore, most existing stream classification approaches assume that the true label of a data point can be accessed immediately after the data point is classified. In reality, a time delay Tl is involved in obtaining the true label of a data point since manual labeling is time consuming. We show how to make fast and correct classification decisions under these constraints and apply them to real benchmark data. Comparison with state-of-the-art stream classification techniques prove the superiority of our approach.

Don't Believe the Hype: Local Media Slant, Local Advertising, and Firm Value

Abstract: When local media report news about local companies, they use fewer negative words compared to the same media reporting about non-local companies. We document that one reason for this positive slant is due to the firms’ local media advertising expenditures. Abnormal positive local media slant strongly relates to firm equity values. The effect is stronger for small firms, firms held predominantly by individual investors, and firms with illiquid or highly volatile stock, low analyst following, or high dispersion of analyst forecasts. These findings show that news content varies systematically with the characteristics and conflicts of interest of the source.

Mobile Visual Search

Abstract: Mobile phones have evolved into powerful image and video processing devices equipped with high-resolution cameras, color displays, and hardware-accelerated graphics. They are also increasingly equipped with a global positioning system and connected to broadband wireless networks. All this enables a new class of applications that use the camera phone to initiate search queries about objects in visual proximity to the user (Figure 1). Such applications can be used, e.g., for identifying products, comparison shopping, finding information about movies, compact disks (CDs), real estate, print media, or artworks.

The 'subduction initiation rule': a key for linking ophiolites, intra-oceanic forearcs, and subduction initiation

Abstract: We establish the ‘subduction initiation rule’ (SIR) which predicts that most ophiolites form during subduction initiation (SI) and that the diagnostic magmatic chemostratigraphic progression for SIR ophiolites is from less to more HFSE-depleted and LILE-enriched compositions. This chemostratigraphic evolution reflects formation of what ultimately becomes forearc lithosphere as a result of mantle melting that is progressively influenced by subduction zone enrichment during SI. The magmatic chemostratigraphic progression for the Izu–Bonin–Mariana (IBM) forearc and most Tethyan ophiolites is specifically from MORB-like to arc-like (volcanic arc basalts or VAB ± boninites or BON) because SI progressed until establishment of a mature subduction zone. MORB-like lavas result from decompression melting of upwelling asthenosphere and are the first magmatic expression of SI. The contribution of fluids from dehydrating oceanic crust and sediments on the sinking slab is negligible in early SI, but continued melting results in a depleted, harzburgitic residue that is progressively metasomatized by fluids from the sinking slab; subsequent partial melting of this residue yields ‘typical’ SSZ-like lavas in the latter stages of SI. If SI is arrested early, e.g., as a result of collision, ‘MORB-only’ ophiolites might be expected. Consequently, MORB- and SSZ-only ophiolites may represent end-members of the SI ophiolite spectrum. The chemostratigraphic similarity of the Mariana forearc with that of ophiolites that follow the SIR intimates that a model linking such ophiolites, oceanic forearcs, and SI is globally applicable.

Biscrolling nanotube sheets and functional guests into yarns.

Abstract: Multifunctional applications of textiles have been limited by the inability to spin important materials into yarns. Generically applicable methods are demonstrated for producing weavable yarns comprising up to 95 weight percent of otherwise unspinnable particulate or nanofiber powders that remain highly functional. Scrolled 50-nanometer-thick carbon nanotube sheets confine these powders in the galleries of irregular scroll sacks whose observed complex structures are related to twist-dependent extension of Archimedean spirals, Fermat spirals, or spiral pairs into scrolls. The strength and electronic connectivity of a small weight fraction of scrolled carbon nanotube sheet enables yarn weaving, sewing, knotting, braiding, and charge collection. This technology is used to make yarns of superconductors, lithium-ion battery materials, graphene ribbons, catalytic nanofibers for fuel cells, and titanium dioxide for photocatalysis.

TDP-43 Is Directed to Stress Granules by Sorbitol, a Novel Physiological Osmotic and Oxidative Stressor

Abstract: TAR DNA-binding protein 43 (TDP-43) is a highly conserved, ubiquitously expressed RNA-binding protein of the heterogeneous nuclear ribonucleoprotein (hnRNP) family (11, 47, 73). TDP-43 and other hnRNPs are multifunctional proteins that regulate gene expression in both the nucleus and the cytoplasm (47, 75). In the nucleus, TDP-43 binds single-stranded DNA and RNA (10, 11, 19, 20, 49, 62) and can function as both a transcriptional repressor (1, 2, 62) and a splicing modulator (15, 17, 20, 55). Specifically, TDP-43 regulates pre-mRNA splicing by binding mRNA with (UG)6-12 sequences (19) and by recruiting other hnRNP proteins into repressive splicing complexes (10, 18, 55). However, as a nucleocytoplasmic shuttling protein (12), TDP-43 also has distinct cytoplasmic functions, including mRNA stabilization (74). Recent studies indicate that TDP-43 localizes to stress granules (SGs) in response to heat shock, oxidative stress, and chemical inducers of stress (23, 33). SGs are dynamic cytoplasmic structures that are believed to act as sorting stations for mRNAs (5). SG composition and morphology differ according to stress and cell type (5, 39), but some core components are conserved. These core components include the RNA-binding protein TIAR (TIA-1 cytotoxic granule-associated RNA-binding protein-like 1) and the stalled translation initiation complex components eIF3 and eIF4G (44, 45). In contrast, the incorporation of the RNA-binding proteins HuR and hnRNP A1 into SGs differs with the cell type and stress (5, 39). The physiological stressors that cause TDP-43 aggregates and SGs to form—and the cells in which this occurs—remain unresolved. Moreover, very little is known about the function of cytoplasmic TDP-43, a pressing issue, since TDP-43 has been linked to multiple neurodegenerative diseases. “TDP-43 proteinopathies” encompass a spectrum of neurodegenerative diseases with ubiquitinated aggregates composed primarily of TDP-43 (21, 35). Ubiquitinated TDP-43 is especially prevalent in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U). In these diseases, many mutations have been identified within the glycine-rich region (GRR) of TDP-43 (∼30 mutations in ALS [37, 48, 51, 63, 66, 69, 72] and 2 in FTLD-U [14, 21, 38, 46]). How TDP-43 contributes to neurodegeneration is not known, but other pathological alterations to TDP-43 implicate aberrant proteolysis, hyperphosphorylation, and misaccumulation in the cytoplasm (7, 16, 21, 35, 59). It is not clear how genetic mutations in TDP-43 contribute to neurodegeneration at the molecular and cellular levels. Existing evidence is compatible with the hypothesis that TDP-43 proteinopathies arise from a gain of TDP-43 function in the cytoplasm due to its misaccumulation in the cytoplasm. This may indirectly or directly impact its nuclear function, since cytoplasmic misaccumulation would reduce the amount of functional TDP-43 in the nuclear compartment. In this study, as a first step toward testing this hypothesis, we build a robust, quantitative, and physiologically relevant cellular model that allows us to establish the conditions under which TDP-43 accumulates in the cytoplasm, such as those seen in TDP-43 proteinopathies. We show that elevated levels of the sugar sorbitol, an intermediate in the polyol pathway (an ATP-independent metabolic route that generates fructose from glucose) (22), result in TDP-43 localization to SGs in Hek293T cells and, similarly, in primary cultured glia. Furthermore, we use this new cellular model to examine the dynamic assembly of TDP-43+ SGs, including the control of SG size and the molecular determinants within TDP-43 necessary for its assembly into SGs. Finally, we use this model to distinguish between the responses of wild-type TDP-43 and pathological mutant TDP-43 to stress. Mutant TDP-43 variants are incorporated into stress granules earlier than wild-type TDP-43, and these mutants form significantly larger stress granules. In striking contrast, wild-type TDP-43 forms more cytoplasmic granules over time, but the granule size remains relatively unchanged. Thus, we establish in this study a simple yet rigorous quantitative, physiologically relevant measurement of TDP-43 aggregate formation in vivo, and we use our novel assay to identify the regions of TDP-43 that contribute to this pathological phenomenon.

Alterations in Cerebral Metabolic Rate and Blood Supply across the Adult Lifespan

Abstract: With age, the brain undergoes comprehensive changes in its function and physiology. Cerebral metabolism and blood supply are among the key physiologic processes supporting the daily function of the brain and may play an important role in age-related cognitive decline. Using MRI, it is now possible to make quantitative assessment of these parameters in a noninvasive manner. In the present study, we concurrently measured cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF), and venous blood oxygenation in a well-characterized healthy adult cohort from 20 to 89 years old (N = 232). Our data showed that CMRO2 increased significantly with age, while CBF decreased with age. This combination of higher demand and diminished supply resulted in a reduction of venous blood oxygenation with age. Regional CBF was also determined, and it was found that the spatial pattern of CBF decline was heterogeneous across the brain with prefrontal cortex, insular cortex, and caudate being the most affected regions. Aside from the resting state parameters, the blood vessels’ ability to dilate, measured by cerebrovascular reactivity to 5% CO2 inhalation, was assessed and was reduced with age, the extent of which was more prominent than that of the resting state CBF.

Consideration of dose limits for organs at risk of thoracic radiotherapy: atlas for lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus.

Abstract: Purpose To review the dose limits and standardize the three-dimenional (3D) radiographic definition for the organs at risk (OARs) for thoracic radiotherapy (RT), including the lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus. Methods and Materials The present study was performed by representatives from the Radiation Therapy Oncology Group, European Organization for Research and Treatment of Cancer, and Soutwestern Oncology Group lung cancer committees. The dosimetric constraints of major multicenter trials of 3D-conformal RT and stereotactic body RT were reviewed and the challenges of 3D delineation of these OARs described. Using knowledge of the human anatomy and 3D radiographic correlation, draft atlases were generated by a radiation oncologist, medical physicist, dosimetrist, and radiologist from the United States and reviewed by a radiation oncologist and medical physicist from Europe. The atlases were then critically reviewed, discussed, and edited by another 10 radiation oncologists. Results Three-dimensional descriptions of the lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus are presented. Two computed tomography atlases were developed: one for the middle and lower thoracic OARs (except for the heart) and one focusing on the brachial plexus for a patient positioned supine with their arms up for thoracic RT. The dosimetric limits of the key OARs are discussed. Conclusions We believe these atlases will allow us to define OARs with less variation and generate dosimetric data in a more consistent manner. This could help us study the effect of radiation on these OARs and guide high-quality clinical trials and individualized practice in 3D-conformal RT and stereotactic body RT.

Vanadium Oxide Nanowire–Carbon Nanotube Binder‐Free Flexible Electrodes for Supercapacitors

Abstract: Vanadium pentoxide (V2O5) layered nanostructures are known to have very stable crystal structures and high faradaic activity. The low electronic conductivity of V2O5 greatly limits the application of vanadium oxide as electrode materials and requires combining with conducting materials using binders. It is well known that the organic binders can degrade the overall performance of electrode materials and need carefully controlled compositions. In this study, we develop a simple method for preparing freestanding carbon nanotube (CNT)-V2O5 nanowire (VNW) composite paper electrodes without using binders. Coin cell type (CR2032) supercapacitors are assembled using the nanocomposite paper electrode as the anode and high surface area carbon fiber electrode (Spectracarb 2225) as the cathode. The supercapacitor with CNT-VNW composite paper electrode exhibits a power density of 5.26 kW Kg−1 and an energy density of 46.3 Wh Kg−1. (Li)VNWs and CNT composite paper electrodes can be fabricated in similar manner and show improved overall performance with a power density of 8.32 kW Kg−1 and an energy density of 65.9 Wh Kg−1. The power and energy density values suggest that such flexible hybrid nanocomposite paper electrodes may be useful for high performance electrochemical supercapacitors.