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MIT Open Access Articles

Mostrando recursos 101 - 120 de 29.946

  1. ERRATUM: “A SMALLER RADIUS FOR THE TRANSITING EXOPLANET WASP-10b” (2009, ApJ, 692, L100)

    Johnson, John Asher; Cabrera, Nicole E.; Winn, Joshua N.; Carter, Joshua Adam
    We have identified an error in our Heliocentric Julian Dates (HJDs) of observation caused by incorrect input to the code used to convert from JD to HJD. The times in Table 1 have been corrected by adding 0.006382 day to each entry in the original Column 1. Similarly, the measured mid-transit time in Table 2 has been changed to Tc = 2454664.037295. We also note that the header in Column 1 of Table 1 is incorrect. The label should read HJD, rather than BJD. The updated Tables 1 and 2 have been included herein. This error has no impact on our...

  2. Branching fraction and CP asymmetry of the decays B[superscript +] → K[subscript 0][superscript S]π[superscript +] and B[superscript +] → K[subscript 0][subscript S] K[supercript +] ✩

    Williams, Michael
    An analysis of B[superscript +] →K[subscript S][superscript 0] π[superscript +] and B[superscript +] →K[subscript S][superscript 0] K[superscript +] decays is performed with the LHCb experiment. The pp collision data used correspond to integrated luminosities of 1fb[superscript -1] and 2fb[superscript -1] collected at centre-of-mass energies of √s=7 TeV and √s=8 TeV, respectively. The ratio of branching fractions and the direct CP asymmetries are measured to be B(B[superscript +] →K[subscript S][superscript 0]K[superscript +])/B(B[superscript +] →K[subscript S][superscript 0] π[superscript +])=0.064 ± 0.009 (stat.) ± 0.004(syst.), A[superscript CP] (B[superscript +] →K[subscript S][superscript 0]π[superscript +])=-0.022 ± 0.025(stat.) ± 0.010 (syst.) and A[superscript CP](B[superscript +] →K[subscript...

  3. Event Shapes and Azimuthal Correlations in Z+jets Events in Pp Collisions at √S=7 TeV

    Apyan, Aram; Bauer, Gerry P; Bendavid, Joshua L.; Busza, Wit; Butz, Erik M.; Cali, Ivan Amos; Chan, Matthew Hans; Dutta, Valentina; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Kim, Yongsun; Klute, Markus; Krajczar, Krisztian F.; Levin, Andrew Michael; Luckey Jr, P David; Ma, Teng; Nahn, Steven; Paus, Christoph M. E.; Ralph, Duncan Kelley; Roland, Christof E; Roland, Gunther M; Rudolph, Matthew Scott; Stephans, George S. F.; Stoeckli, Fabian; Sumorok, Konstanty C; Sung, Kevin Kai Hong; Velicanu, Dragos Alexandru; Wenger, Edward Allen; Wolf, Roger; Wyslouch, Boleslaw; Yang, Mingming; Yilmaz, Yetkin; Yoon, Andrew; Zanetti, Marco; Wyslouch, Victoria
    Measurements of event shapes and azimuthal correlations are presented for events where a Z boson is produced in association with jets in proton-proton collisions. The data collected with the CMS detector at the CERN LHC at √s=7 TeV correspond to an integrated luminosity of 5.0 fb[superscript −1]. The analysis provides a test of predictions from perturbative QCD for a process that represents a substantial background to many physics channels. Results are presented as a function of jet multiplicity, for inclusive Z boson production and for Z bosons with transverse momenta greater than 150 GeV, and compared to predictions from Monte...

  4. Compliant Electric Actuators Based on Handed Shearing Auxetics

    Chin, Lillian T.; Lipton, Jeffrey I; MacCurdy, Robert; Romanishin, John W; Sharma, Chetan; Rus, Daniela L
    In this paper, we explore a new class of electric motor-driven compliant actuators based on handed shearing auxetic cylinders. This technique combines the benefits of compliant bodies from soft robotic actuators with the simplicity of direct coupling to electric motors. We demonstrate the effectiveness of this technique by creating linear actuators, a four degree-of-freedom robotic platform, and a soft robotic gripper. We compare the soft robotic gripper against a state of the art pneumatic soft gripper, finding similar grasping performance in a significantly smaller and more energy-efficient package.

  5. Prevention of myopia by partial correction of hyperopia: a twins study

    Medina, Alan
    Purpose To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic. Methods We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16. Results Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values. Conclusions The treatment of the twins with partial...

  6. Minimum local distance density estimation

    Tenorio, Luis; Garg, Vikram V; Willcox, Karen E
    We present a local density estimator based on first-order statistics. To estimate the density at a point, x, the original sample is divided into subsets and the average minimum sample distance to x over all such subsets is used to define the density estimate at x. The tuning parameter is thus the number of subsets instead of the typical bandwidth of kernel or histogram-based density estimators. The proposed method is similar to nearest-neighbor density estimators but it provides smoother estimates. We derive the asymptotic distribution of this minimum sample distance statistic to study globally optimal values for the number and...

  7. A Certified Trust Region Reduced Basis Approach to PDE-Constrained Optimization

    Grepl, Martin; Veroy, Karen; Qian, Elizabeth Y.; Willcox, Karen E
    Parameter optimization problems constrained by partial differential equations (PDEs) appear in many science and engineering applications. Solving these optimization problems may require a prohibitively large number of computationally expensive PDE solves, especially if the dimension of the design space is large. It is therefore advantageous to replace expensive high-dimensional PDE solvers (e.g., finite element) with lower-dimensional surrogate models. In this paper, the reduced basis (RB) model reduction method is used in conjunction with a trust region optimization framework to accelerate PDE-constrained parameter optimization. Novel a posteriori error bounds on the RB cost and cost gradient for quadratic cost functionals (e.g.,...

  8. A classification model for non-alcoholic steatohepatitis (NASH) using confocal Raman micro-spectroscopy

    Yu, Yang; Tam, Zhi Yang; Xu, Shuo Yu; Fong, Eliza Li Shan; Singh, Surya Pratap; Song, Ziwei; Kellogg, Lisa Tucker; So, Peter; Yu, Hanry; Yan, Jie; Kang, Jeon Woong
    We combined Raman micro-spectroscopy and machine learning techniques to develop a classification model based on a well-established non-alcoholic steatohepatitis (NASH) mouse model, using spectrum pre-processing, biochemical component analysis (BCA) and logistic regression.

  9. The TESS science processing operations center

    Jenkins, Jon M.; Twicken, Joseph D.; McCauliff, Sean; Campbell, Jennifer; Sanderfer, Dwight; Lung, David; Mansouri-Samani, Masoud; Girouard, Forrest; Tenenbaum, Peter; Klaus, Todd; Smith, Jeffrey C.; Caldwell, Douglas A.; Chacon, A. D.; Henze, Christopher; Heiges, Cory; Latham, David W.; Swade, Daryl; Rinehart, Stephen; Vanderspek, Roland; Morgan, Edward H
    The Transiting Exoplanet Survey Satellite (TESS) will conduct a search for Earth's closest cousins starting in early 2018 and is expected to discover ∼1,000 small planets with R[subscript p] < 4 R[subscript ⊕] and measure the masses of at least 50 of these small worlds. The Science Processing Operations Center (SPOC) is being developed at NASA Ames Research Center based on the Kepler science pipeline and will generate calibrated pixels and light curves on the NASA Advanced Supercomputing Division's Pleiades supercomputer. The SPOC will also search for periodic transit events and generate validation products for the transit-like features in the...

  10. B meson decays to charmless meson pairs containing η or η' mesons

    Cowan, Ray F; Dujmic, Denis; Fisher, Peter H; Henderson, Shawn Wesley; Sciolla, Gabriella; Spitznagel, Michael A; Yamamoto, Richard K; Zhao, Min Liang
    We present updated measurements of the branching fractions for B[superscript 0] meson decays to ηK[superscript 0], ηη, ηφ, ηω, η′K[superscript 0], η′η′, η′φ, and η′ω, and branching fractions and CP-violating charge asymmetries for B[superscript +] decays to ηπ[superscript +], ηK[superscript +], η′π[superscript +], and η′K[superscript +]. The data represent the full data set of 467×10[superscript 6] BB̄ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e[superscript +]e[superscript -] collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B[superscript 0]→η′K[superscript 0], we find evidence for three B[superscript 0] decay...

  11. Neyman-pearson classiffication under high-dimensional settings

    Zhao, Anqi; Feng, Yang; Tong, Xin; Wang, Lie
    Most existing binary classification methods target on the optimization of the overall classification risk and may fail to serve some real-world applications such as cancer diagnosis, where users are more concerned with the risk of misclassifying one specific class than the other. Neyman-Pearson (NP) paradigm was introduced in this context as a novel statistical framework for handling asymmetric type I/II error priorities. It seeks classifiers with a minimal type II error and a constrained type I error under a user specified level. This article is the first attempt to construct classifiers with guaranteed theoretical performance under the NP paradigm in...

  12. Anthropogenic Space Weather

    Balogh, A.; Gombosi, T. I.; Baker, D. N.; Huba, J. D.; Lanzerotti, L. J.; Erickson, Philip J
    Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release experiments, high-frequency wave heating of the ionosphere and the interaction of...

  13. Antagonistic negative and positive neurons of the basolateral amygdala

    Itohara, Shigeyoshi; Kim, Joshua; Pignatelli di Spinazzola, Michele; Xu, Sangyu; Tonegawa, Susumu
    The basolateral amygdala (BLA) is a site of convergence of negative and positive stimuli and is critical for emotional behaviors and associations. However, the neural substrate for negative and positive behaviors and relationship between negative and positive representations in the basolateral amygdala are unknown. Here we identify two genetically distinct, spatially segregated populations of excitatory neurons in the mouse BLA that participate in valence-specific behaviors and are connected through mutual inhibition. These results identify a genetically defined neural circuit for the antagonistic control of emotional behaviors and memories.

  14. Basolateral to Central Amygdala Neural Circuits for Appetitive Behaviors

    Kim, Joshua; Zhang, Xiangyu; Muralidhar, Shruti; LeBlanc, Sarah Anne; Tonegawa, Susumu
    Basolateral amygdala (BLA) principal cells are capable of driving and antagonizing behaviors of opposing valence. BLA neurons project to the central amygdala (CeA), which also participates in negative and positive behaviors. However, the CeA has primarily been studied as the site for negative behaviors, and the causal role for CeA circuits underlying appetitive behaviors is poorly understood. Here, we identify several genetically distinct populations of CeA neurons that mediate appetitive behaviors and dissect the BLA-to-CeA circuit for appetitive behaviors. Protein phosphatase 1 regulatory subunit 1B⁺ BLA pyramidal neurons to dopamine receptor 1⁺ CeA neurons define a pathway for promoting appetitive...

  15. Engrams and circuits crucial for systems consolidation of a memory

    Kitamura, Takashi; Kitamura, Sachie Ogawa; Roy, Dheeraj; Okuyama, Teruhiro; Morrissey, Mark; Smith, Lillian; Redondo Pena, Roger L; Tonegawa, Susumu
    Episodic memories initially require rapid synaptic plasticity within the hippocampus for their formation and are gradually consolidated in neocortical networks for permanent storage. However, the engrams and circuits that support neocortical memory consolidation have thus far been unknown.We found that neocortical prefrontal memory engram cells, which are critical for remote contextual fear memory, were rapidly generated during initial learning through inputs from both the hippocampal-entorhinal cortex network and the basolateral amygdala. After their generation, the prefrontal engram cells, with support from hippocampal memory engram cells, became functionally mature with time. Whereas hippocampal engram cells gradually became silent with time, engram...

  16. Pathobiology of Human Uterine Leiomyosarcoma for Development of Novel Diagnosis and Clinical Therapy

    Hayashi, Takuma; Ichimura, Tomoyuki; Kasai, Mari; Gur, Gal; Yaish, Pnina; Zharhary, Dorit; Kanai, Yae; Yaegashi, Nobuo; Konishi, Ikuo; Tonegawa, Susumu
    Uterine sarcomas comprise a group of rare tumours with differing tumour pathobiology, natural history and response to clinical treatment. Diagnosis is often made following surgical treatment for presumed malignant mesenchymal tumours and benign tumours. Currently pre-operative diagnosis does not reliably distinguish between malignant mesenchymal tumours, Uterine Leiomyosarcoma (U-LMS) and benign tumours including Leiomyomas (LMA). U-LMS is the most common sarcoma but other subtypes include endometrial stromal sarcoma (low grade and high grade), undifferentiated uterine sarcoma and adeno sarcoma. Clinical trials have shown no definite survival benefit for adjuvant radiotherapy or chemotherapy, and have been hampered by the rarity and heterogeneity...

  17. The somatic mutations in Interferon-γ signal molecules in human uterine leiomyosarcoma

    Hayashi, Takuma; Ichimura, Tomoyuki; Kasai, Mari; Ando, Hirofumi; Ida, Koichi; Kawano, Miki; Shiozawa, Tanri; Kanai, Yae; Aburatani, Hiroyuki; Yaegashi, Nobuo; Konishi, Ikuo; Tonegawa, Susumu
    Human uterine leiomyosarcoma (U-LMS) is neoplastic malignancy that typically arises in tissues of mesenchymal origin. The identification of novel molecular mechanism leading to human U-LMS formation and the establishment of new therapies has been hampered by several critical points. We earlier reported that mice with a homozygous deficiency for proteasome beta subunit 9 (Psmb9)/β1i, an interferon (IFN)-γ inducible factor, spontaneously develop U-LMS. The use of research findings of the experiment with mouse model has been successful in increasing our knowledge and understanding of how alterations, in relevant oncogenic, tumour suppressive, and signaling pathways directly impact sarcomagenesis. The IFN-γ pathway is...

  18. Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

    Abe, Kuniya; Wagatsuma, Akiko; Okuyama, Teruhiro; Sun, Chen; Smith, Lillian; Tonegawa, Susumu
    The memory for a new episode is formed immediately upon experience and can last up to a lifetime. It has been shown that the hippocampal network plays a fundamental role in the rapid acquisition of a memory of a one-time experience, in which the novelty component of the experience promotes the prompt formation of the memory. However, it remains unclear which neural circuits convey the novelty signal to the hippocampus for the single-trial learning. Here, we show that during encoding neuromodulatory input from locus coeruleus (LC) to CA3, but not CA1 or to the dentate gyrus, is necessary to facilitate...

  19. The 16p11.2 homologs fam57ba and doc2a generate certain brain and body phenotypes

    McCammon, Jasmine M.; Blaker-Lee, Alicia; Chen, Xiao; Sive, Hazel L
    Deletion of the 16p11.2 CNV affects 25 core genes and is associated with multiple symptoms affecting brain and body, including seizures, hyperactivity,macrocephaly, and obesity. Available data suggest thatmost symptoms are controlled by haploinsufficiency of two or more 16p11.2 genes. To identify interacting 16p11.2 genes, we used a pairwise partial loss of function antisense screen for embryonic brainmorphology, using the accessible zebrafish model. fam57ba, encoding a ceramide synthase, was identified as interacting with the doc2a gene, encoding a calcium-sensitive exocytosis regulator, a genetic interaction not previously described. Using genetic mutants, we demonstrated that doc2a+/-fam57ba+/-double heterozygotes show hyperactivity and increased seizure susceptibility...

  20. Quantifying argonaute proteins in and out of GW/P-bodies: Implications in microRNA activities

    Leung, Anthony K. L.; Sharp, Phillip A.
    MicroRNAs (miRNAs) are a class of ∼22nt non-coding RNAs that regulate the translational potential and stability of mRNAs. Though constituting only 1-4% of human genes, miRNAs are predicted to regulate more than 60% of all mRNAs. The action of miRNAs is mediated through their associations with Argonaute proteins and mRNA targets. Previous studies indicated that though the majority of Argonaute proteins is diffusely distributed in the cytoplasm, a small fraction is consistently observed to be concentrated in a cytoplasmic compartment called GW/P-bodies. In this chapter, we will provide a quantitative and dynamic view of the subcellular localization of miRNA function,...

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