@article{17626, abstract = {Weak gravitational lensing is becoming a mature technique for constraining cosmological parameters, and future surveys will be able to constrain the dark energy equation of state 𝑤. When analyzing galaxy surveys, redshift information has proven to be a valuable addition to angular shear correlations. We forecast parameter constraints on the triplet (Ω𝑚,𝑤,𝜎8) for a LSST-like photometric galaxy survey, using tomography of the shear-shear power spectrum, convergence peak counts and higher convergence moments. We find that redshift tomography with the power spectrum reduces the area of the 1⁢𝜎 confidence interval in (Ω𝑚,𝑤) space by a factor of 8 with respect to the case of the single highest redshift bin. We also find that adding non-Gaussian information from the peak counts and higher-order moments of the convergence field and its spatial derivatives further reduces the constrained area in (Ω𝑚,𝑤) by factors of 3 and 4, respectively. When we add cosmic microwave background parameter priors from Planck to our analysis, tomography improves power spectrum constraints by a factor of 3. Adding moments yields an improvement by an additional factor of 2, and adding both moments and peaks improves by almost a factor of 3 over power spectrum tomography alone. We evaluate the effect of uncorrected systematic photometric redshift errors on the parameter constraints. We find that different statistics lead to different bias directions in parameter space, suggesting the possibility of eliminating this bias via self-calibration.}, author = {Petri, Andrea and May, Morgan and Haiman, Zoltán}, issn = {2470-0010}, journal = {Physical Review D}, number = {6}, publisher = {American Physical Society}, title = {{Cosmology with photometric weak lensing surveys: Constraints with redshift tomography of convergence peaks and moments}}, doi = {10.1103/physrevd.94.063534}, volume = {94}, year = {2016}, } @article{17628, abstract = {Constraining cosmology using weak gravitational lensing consists of comparing a measured feature vector of dimension 𝑁𝑏 with its simulated counterpart. An accurate estimate of the 𝑁𝑏×𝑁𝑏 feature covariance matrix 𝐂 is essential to obtain accurate parameter confidence intervals. When 𝐂 is measured from a set of simulations, an important question is how large this set should be. To answer this question, we construct different ensembles of 𝑁𝑟 realizations of the shear field, using a common randomization procedure that recycles the outputs from a smaller number 𝑁𝑠≤𝑁𝑟 of independent ray-tracing 𝑁-body simulations. We study parameter confidence intervals as a function of (𝑁𝑠, 𝑁𝑟) in the range 1≤𝑁𝑠≤200 and 1≤𝑁𝑟≲105. Previous work [S. Dodelson and M. D. Schneider, Phys. Rev. D 88, 063537 (2013)] has shown that Gaussian noise in the feature vectors (from which the covariance is estimated) lead, at quadratic order, to an 𝑂⁢(1/𝑁𝑟) degradation of the parameter confidence intervals. Using a variety of lensing features measured in our simulations, including shear-shear power spectra and peak counts, we show that cubic and quartic covariance fluctuations lead to additional 𝑂⁢(1/𝑁2𝑟) error degradation that is not negligible when 𝑁𝑟 is only a factor of few larger than 𝑁𝑏. We study the large 𝑁𝑟 limit, and find that a single, 240  Mpc/ℎ sized 5123-particle 𝑁-body simulation (𝑁𝑠=1) can be repeatedly recycled to produce as many as 𝑁𝑟=few×104 shear maps whose power spectra and high-significance peak counts can be treated as statistically independent. As a result, a small number of simulations (𝑁𝑠=1 or 2) is sufficient to forecast parameter confidence intervals at percent accuracy.}, author = {Petri, Andrea and Haiman, Zoltán and May, Morgan}, issn = {2470-0010}, journal = {Physical Review D}, number = {6}, publisher = {American Physical Society}, title = {{Sample variance in weak lensing: How many simulations are required?}}, doi = {10.1103/physrevd.93.063524}, volume = {93}, year = {2016}, } @article{17649, abstract = {Weak lensing convergence peaks are a promising tool to probe nonlinear structure evolution at late times, providing additional cosmological information beyond second-order statistics. Previous theoretical and observational studies have shown that the cosmological constraints on Ωm and σ8 are improved by a factor of up to ~ 2 when peak counts and second-order statistics are combined, compared to using the latter alone. We study the origin of lensing peaks using observational data from the 154 deg2 Canada-France-Hawaii Telescope Lensing Survey. We found that while high peaks (with height κ >3.5 σκ, where σκ is the r.m.s. of the convergence κ) are typically due to one single massive halo of ~1015M⊙, low peaks (κ <~ σκ) are associated with constellations of 2-8 smaller halos (<~1013M⊙). In addition, halos responsible for forming low peaks are found to be significantly offset from the line-of-sight towards the peak center (impact parameter >~ their virial radii), compared with ~0.25 virial radii for halos linked with high peaks, hinting that low peaks are more immune to baryonic processes whose impact is confined to the inner regions of the dark matter halos. Our findings are in good agreement with results from the simulation work by Yang el al. (2011).}, author = {Liu, Jia and Haiman, Zoltán}, issn = {2470-0010}, journal = {Physical Review D}, number = {4}, publisher = {American Physical Society}, title = {{Origin of weak lensing convergence peaks}}, doi = {10.1103/physrevd.94.043533}, volume = {94}, year = {2016}, } @article{17654, abstract = {We explore the formation of massive high-redshift Population III (Pop III) galaxies through photoionization feedback. We consider dark matter haloes formed from progenitors that have undergone no star formation as a result of early reionization and photoevaporation caused by a nearby galaxy. Once such a halo reaches ≈109 M⊙, corresponding to the Jeans mass of the photoheated intergalactic medium at z ≈ 7, pristine gas is able to collapse into the halo, potentially producing a massive Pop III starburst. We suggest that this scenario may explain the recent observation of strong He ii 1640 Å line emission in CR 7, which is consistent with ∼107 M⊙ of young Pop III stars. Such a large mass of Pop III stars is unlikely without the photoionization feedback scenario, because star formation is expected to inject metals into haloes above the atomic cooling threshold (∼108 M⊙ at z ≈ 7). We use merger trees to analytically estimate the abundance of observable Pop III galaxies formed through this channel, and find a number density of ≈10−7 Mpc−3 at z = 6.6 (the redshift of CR 7). This is approximately a factor of 10 lower than the density of Ly α emitters as bright as CR 7.}, author = {Visbal, Eli and Haiman, Zoltán and Bryan, Greg L.}, issn = {1745-3925}, journal = {Monthly Notices of the Royal Astronomical Society: Letters}, number = {1}, pages = {L59--L63}, publisher = {Oxford University Press}, title = {{Formation of massive Population III galaxies through photoionization feedback: A possible explanation for CR 7}}, doi = {10.1093/mnrasl/slw071}, volume = {460}, year = {2016}, } @article{17656, abstract = {We explore the evolution of stellar mass black hole binaries (BHBs) which are formed in the self-gravitating discs of active galactic nuclei (AGN). Hardening due to three-body scattering and gaseous drag are effective mechanisms that reduce the semimajor axis of a BHB to radii where gravitational waves take over, on time-scales shorter than the typical lifetime of the AGN disc. Taking observationally motivated assumptions for the rate of star formation in AGN discs, we find a rate of disc-induced BHB mergers (⁠| $\mathcal {R} \sim 3\ {\rm yr}^{-1}\ {\rm Gpc}^{-3}$ |⁠, but with large uncertainties) that is comparable with existing estimates of the field rate of BHB mergers, and the approximate BHB merger rate implied by the recent Advanced LIGO detection of GW150914. BHBs formed thorough this channel will frequently be associated with luminous AGN, which are relatively rare within the sky error regions of future gravitational wave detector arrays. This channel could also possess a (potentially transient) electromagnetic counterpart due to super-Eddington accretion on to the stellar mass black hole following the merger.}, author = {Stone, Nicholas C. and Metzger, Brian D. and Haiman, Zoltán}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {1}, pages = {946--954}, publisher = {Oxford University Press}, title = {{Assisted inspirals of stellar mass black holes embedded in AGN discs: Solving the ‘final au problem’}}, doi = {10.1093/mnras/stw2260}, volume = {464}, year = {2016}, } @article{17658, abstract = {We study circumbinary accretion discs in the framework of the restricted three-body problem (R3Bp) and via numerically solving the height-integrated equations of viscous hydrodynamics. Varying the mass ratio of the binary, we find a pronounced change in the behaviour of the disc near mass ratio q ≡ Ms/Mp ∼ 0.04. For mass ratios above q = 0.04, solutions for the hydrodynamic flow transition from steady, to strongly fluctuating; a narrow annular gap in the surface density around the secondary's orbit changes to a hollow central cavity; and a spatial symmetry is lost, resulting in a lopsided disc. This phase transition is coincident with the mass ratio above which stable orbits do not exist around the L4 and L5 equilibrium points of the R3Bp. Using the disco code, we find that for thin discs, for which a gap or cavity can remain open, the mass ratio of the transition is relatively insensitive to disc viscosity and pressure. The q = 0.04 transition has relevance for the evolution of massive black hole binary+disc systems at the centres of galactic nuclei, as well as for young stellar binaries and possibly planets around brown dwarfs.}, author = {D'Orazio, Daniel J. and Haiman, Zoltán and Duffell, Paul and MacFadyen, Andrew and Farris, Brian}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, pages = {2379--2393}, publisher = {Oxford University Press}, title = {{A transition in circumbinary accretion discs at a binary mass ratio of 1:25}}, doi = {10.1093/mnras/stw792}, volume = {459}, year = {2016}, } @article{17659, abstract = {The recent discovery of the gravitational wave source GW150914 has revealed a coalescing binary black hole (BBH) with masses of ∼30 M⊙. Previous proposals for the origin of such a massive binary include Population III (PopIII) stars. PopIII stars are efficient producers of BBHs and of a gravitational wave background (GWB) in the 10–100 Hz band, and also of ionizing radiation in the early Universe. We quantify the relation between the amplitude of the GWB (Ωgw) and the electron scattering optical depth (τe), produced by PopIII stars, assuming that fesc ≈ 10 per cent of their ionizing radiation escapes into the intergalactic medium. We find that PopIII stars would produce a GWB that is detectable by the future O5 LIGO/Virgo if τe ≳ 0.07, consistent with the recent Planck measurement of τe = 0.055 ± 0.09. Moreover, the spectral index of the background from PopIII BBHs becomes as small as dln Ωgw/dln f ≲ 0.3 at f ≳ 30 Hz, which is significantly flatter than the value ∼2/3 generically produced by lower redshift and less-massive BBHs. A detection of the unique flattening at such low frequencies by the O5 LIGO/Virgo will indicate the existence of a high-chirp mass, high-redshift BBH population, which is consistent with the PopIII origin. A precise characterization of the spectral shape near 30–50 Hz by the Einstein Telescope could also constrain the PopIII initial mass function and star formation rate.}, author = {Inayoshi, Kohei and Kashiyama, Kazumi and Visbal, Eli and Haiman, Zoltán}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, pages = {2722--2727}, publisher = {Oxford University Press}, title = {{Gravitational wave background from Population III binary black holes consistent with cosmic reionization}}, doi = {10.1093/mnras/stw1431}, volume = {461}, year = {2016}, } @article{17666, abstract = {We have investigated a recently proposed halo-based model, Camelus, for predicting weak-lensing peak counts, and compared its results over a collection of 162 cosmologies with those from N-body simulations. While counts from both models agree for peaks with S/N>1 (where S/N is the ratio of the peak height to the r.m.s. shape noise), we find ≈50% fewer counts for peaks near S/N=0 and significantly higher counts in the negative S/N tail. Adding shape noise reduces the differences to within 20% for all cosmologies. We also found larger covariances that are more sensitive to cosmological parameters. As a result, credibility regions in the {Ωm,σ8} are ≈30% larger. Even though the credible contours are commensurate, each model draws its predictive power from different types of peaks. Low peaks, especially those with 23). Our results confirm the importance of using a cosmology-dependent covariance with at least a 14\% improvement in parameter constraints. We identified the covariance estimation as the main driver behind differences in inference, and suggest possible ways to make Camelus even more useful as a highly accurate peak count emulator.}, author = {Zorrilla Matilla, José Manuel and Haiman, Zoltán and Hsu, Daniel and Gupta, Arushi and Petri, Andrea}, issn = {2470-0010}, journal = {Physical Review D}, number = {8}, publisher = {American Physical Society}, title = {{Do dark matter halos explain lensing peaks?}}, doi = {10.1103/physrevd.94.083506}, volume = {94}, year = {2016}, } @article{17669, abstract = {Unprecedentedly precise cosmic microwave background (CMB) data are expected from ongoing and near-future CMB Stage-III and IV surveys, which will yield reconstructed CMB lensing maps with effective resolution approaching several arcminutes. The small-scale CMB lensing fluctuations receive non-negligible contributions from nonlinear structure in the late-time density field. These fluctuations are not fully characterized by traditional two-point statistics, such as the power spectrum. Here, we use N-body ray-tracing simulations of CMB lensing maps to examine two higher-order statistics: the lensing convergence one-point probability distribution function (PDF) and peak counts. We show that these statistics contain significant information not captured by the two-point function, and provide specific forecasts for the ongoing Stage-III Advanced Atacama Cosmology Telescope (AdvACT) experiment. Considering only the temperature-based reconstruction estimator, we forecast 9σ (PDF) and 6σ (peaks) detections of these statistics with AdvACT. Our simulation pipeline fully accounts for the non-Gaussianity of the lensing reconstruction noise, which is significant and cannot be neglected. Combining the power spectrum, PDF, and peak counts for AdvACT will tighten cosmological constraints in the Ωm-σ8 plane by ≈30%, compared to using the power spectrum alone.}, author = {Liu, Jia and Hill, J. Colin and Sherwin, Blake D. and Petri, Andrea and Böhm, Vanessa and Haiman, Zoltán}, issn = {2470-0010}, journal = {Physical Review D}, number = {10}, publisher = {American Physical Society}, title = {{CMB lensing beyond the power spectrum: Cosmological constraints from the one-point probability distribution function and peak counts}}, doi = {10.1103/physrevd.94.103501}, volume = {94}, year = {2016}, } @article{17672, abstract = {Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circum-binary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35 383 spectroscopically confirmed quasars in the photometric data base of the Palomar Transient Factory (PTF). We analysed Lomb–Scargle periodograms and assessed the significance of our findings by modelling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PTF and the Catalina Real-Time Transient Survey. Assuming that the observed periods correspond to the redshifted orbital periods of SMBHBs, we conclude that our findings are consistent with a population of unequal-mass SMBHBs, with a typical mass ratio as low as q ≡ M2/M1 ≈ 0.01.}, author = {Charisi, M. and Bartos, I. and Haiman, Zoltán and Price-Whelan, A. M. and Graham, M. J. and Bellm, E. C. and Laher, R. R. and Márka, S.}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {2}, pages = {2145--2171}, publisher = {Oxford University Press}, title = {{A population of short-period variable quasars from PTF as supermassive black hole binary candidates}}, doi = {10.1093/mnras/stw1838}, volume = {463}, year = {2016}, } @article{17693, abstract = {We perform one-dimensional radiation hydrodynamical simulations to solve accretion flows onto massive black holes (BHs) with a very high rate. Assuming that photon trapping limits the luminosity emerging from the central region to L≲LEdd, Inayoshi, Haiman & Ostriker (2016) have shown that an accretion flow settles to a "hyper-Eddington" solution, with a steady and isothermal (T≃8000 K) Bondi profile reaching ≳5000 times the Eddington accretion rate M˙Edd≡LEdd/c2. Here we address the possibility that gas accreting with finite angular momentum forms a bright nuclear accretion disc, with a luminosity exceeding the Eddington limit (1≲L/LEdd≲100). Combining our simulations with an analytic model, we find that a transition to steady hyper-Eddington accretion still occurs, as long as the luminosity remains below L/LEdd≲35 (MBH/10^4 M⊙)^3/2(n∞/10^5 cm^−3)(T∞/10^4 K)^−3/2(r⋆/10^14 cm)^−1/2, where n∞ and T∞ are the density and temperature of the ambient gas, and r⋆ is the radius of the photosphere, at which radiation emerges. If the luminosity exceeds this value, accretion becomes episodic. Our results can be accurately recovered in a toy model of an optically thick spherical shell, driven by radiation force into a collapsing medium. When the central source is dimmer than the above critical value, the expansion of the shell is halted and reversed by ram pressure of the collapsing medium, and by shell's weight. Our results imply that rapid, unimpeded hyper-Eddington accretion is possible even if the luminosity of the central source far exceeds the Eddington limit, and can be either steady or strongly episodic.}, author = {Sakurai, Yuya and Inayoshi, Kohei and Haiman, Zoltán}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {4}, pages = {4496--4504}, publisher = {Oxford University Press}, title = {{Hyper-Eddington mass accretion on to a black hole with super-Eddington luminosity}}, doi = {10.1093/mnras/stw1652}, volume = {461}, year = {2016}, } @article{17699, abstract = {We quantify the presence of Ly\alpha\ damping wing absorption from a partially-neutral intergalactic medium (IGM) in the spectrum of the z=7.08 QSO, ULASJ1120+0641. Using a Bayesian framework, we simultaneously account for uncertainties in: (i) the intrinsic QSO emission spectrum; and (ii) the distribution of cosmic HI patches during the epoch of reionisation (EoR). For (i) we use a new intrinsic Ly\alpha\ emission line reconstruction method (Greig et al.), sampling a covariance matrix of emission line properties built from a large database of moderate-z QSOs. For (ii), we use the Evolution of 21-cm Structure (EOS; Mesinger et al.) simulations, which span a range of physically-motivated EoR models. We find strong evidence for the presence of damping wing absorption redward of Ly\alpha\ (where there is no contamination from the Ly\alpha\ forest). Our analysis implies that the EoR is not yet complete by z=7.1, with the volume-weighted IGM neutral fraction constrained to x¯HI=0.40+0.21−0.19 at 1σ (x¯HI=0.40+0.41−0.32 at 2σ). This result is insensitive to the EoR morphology. Our detection of significant neutral HI in the IGM at z=7.1 is consistent with the latest Planck 2016 measurements of the CMB Thompson scattering optical depth (Planck Collaboration XLVII).}, author = {Greig, Bradley and Mesinger, Andrei and Haiman, Zoltán and Simcoe, Robert A.}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, publisher = {Oxford University Press}, title = {{Are we witnessing the epoch of reionization at z=7.1 from the spectrum of J1120+0641?}}, doi = {10.1093/mnras/stw3351}, year = {2016}, } @article{17700, abstract = {We report the formation of intermediate-mass black holes (IMBHs) in suites of numerical N-body simulations of Population III remnant black holes (BHs) embedded in gas-rich protogalaxies at redshifts z≳10. We model the effects of gas drag on the BHs' orbits, and allow BHs to grow via gas accretion, including a mode of hyper-Eddington accretion in which photon trapping and rapid gas inflow suppress any negative radiative feedback. Most initial BH configurations lead to the formation of one (but never more than one) IMBH in the center of the protogalaxy, reaching a mass of 10^3−5M⊙ through hyper-Eddington growth. Our results suggest a viable pathway to forming the earliest massive BHs in the centers of early galaxies. We also find that the nuclear IMBH typically captures a stellar-mass BH companion, making these systems observable in gravitational waves as extreme mass-ratio inspirals (EMRIs) with eLISA.}, author = {Ryu, Taeho and Tanaka, Takamitsu L. and Perna, Rosalba and Haiman, Zoltán}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {4}, pages = {4122--4134}, publisher = {Oxford University Press}, title = {{Intermediate-mass black holes from Population III remnants in the first galactic nuclei}}, doi = {10.1093/mnras/stw1241}, volume = {460}, year = {2016}, } @article{17709, abstract = {We study very-high rate spherically symmetric accretion flows onto a massive black hole (BH; 10^2 < M_BH < 10^6 Msun) embedded in a dense gas cloud with a low abundance of metals, performing one-dimensional hydrodynamical simulations which include multi-frequency radiation transfer and non-equilibrium primordial chemistry. We find that rapid gas supply from the Bondi radius at a hyper-Eddington rate can occur without being impeded by radiation feedback when (n/10^5 cm^-3) > (M_BH/10^4Msun)^{-1}(T/10^4 K)^{3/2}, where n and T are the density and temperature of ambient gas outside of the Bondi radius. The resulting accretion rate in this regime is steady, and larger than 3000 times the Eddington rate. At lower Bondi rates, the accretion is episodic due to radiative feedback and the average rate is limited below the Eddington rate. For the hyper-Eddington case, the steady solution consists of two parts: a radiation-dominated central core, where photon trapping due to electron scattering is important, and an accreting envelope which follows a Bondi profile with T~8000 K. When the emergent luminosity is limited below the Eddington luminosity because of photon trapping, radiation from the central region does not affect the gas dynamics at larger scales. We apply our result to the rapid formation of massive BHs in protogalaxies with a virial temperature of T_vir> 10^4 K. Once a seed BH forms at the center of the galaxy, it can grow up to a maximum ~10^5 (T_vir/10^4 K) Msun via gas accretion independent of the initial BH mass. Finally, we discuss possible observational signatures of rapidly accreting BHs with/without allowance for dust. We suggest that these systems could explain Lya emitters without X-rays and luminous infrared sources with hot dust emission, respectively.}, author = {Inayoshi, Kohei and Haiman, Zoltán and Ostriker, Jeremiah P.}, issn = {0035-8711}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {4}, pages = {3738--3755}, publisher = {Oxford University Press}, title = {{Hyper-Eddington accretion flows on to massive black holes}}, doi = {10.1093/mnras/stw836}, volume = {459}, year = {2016}, } @article{7737, abstract = {Genome-wide association studies (GWAS) have identified thousands of genetic variants associated with human complex traits. However, the genes or functional DNA elements through which these variants exert their effects on the traits are often unknown. We propose a method (called SMR) that integrates summary-level data from GWAS with data from expression quantitative trait locus (eQTL) studies to identify genes whose expression levels are associated with a complex trait because of pleiotropy. We apply the method to five human complex traits using GWAS data on up to 339,224 individuals and eQTL data on 5,311 individuals, and we prioritize 126 genes (for example, TRAF1 and ANKRD55 for rheumatoid arthritis and SNX19 and NMRAL1 for schizophrenia), of which 25 genes are new candidates; 77 genes are not the nearest annotated gene to the top associated GWAS SNP. These genes provide important leads to design future functional studies to understand the mechanism whereby DNA variation leads to complex trait variation.}, author = {Zhu, Zhihong and Zhang, Futao and Hu, Han and Bakshi, Andrew and Robinson, Matthew Richard and Powell, Joseph E and Montgomery, Grant W and Goddard, Michael E and Wray, Naomi R and Visscher, Peter M and Yang, Jian}, issn = {1061-4036}, journal = {Nature Genetics}, number = {5}, pages = {481--487}, publisher = {Springer Nature}, title = {{Integration of summary data from GWAS and eQTL studies predicts complex trait gene targets}}, doi = {10.1038/ng.3538}, volume = {48}, year = {2016}, } @article{786, abstract = {Lock-free concurrent algorithms guarantee that some concurrent operation will always make progress in a finite number of steps. Yet programmers prefer to treat concurrent code as if it were wait-free, guaranteeing that all operations always make progress. Unfortunately, designing wait-free algorithms is generally a very complex task, and the resulting algorithms are not always efficient. Although obtaining efficient wait-free algorithms has been a long-time goal for the theory community, most nonblocking commercial code is only lock-free. This article suggests a simple solution to this problem.We show that for a large class of lock-free algorithms, under scheduling conditions that approximate those found in commercial hardware architectures, lock-free algorithms behave as if they are wait-free. In other words, programmers can continue to design simple lock-free algorithms instead of complex wait-free ones, and in practice, they will get wait-free progress. Our main contribution is a new way of analyzing a general class of lock-free algorithms under a stochastic scheduler. Our analysis relates the individual performance of processes to the global performance of the system using Markov chain lifting between a complex per-process chain and a simpler system progress chain. We show that lock-free algorithms are not only wait-free with probability 1 but that in fact a general subset of lock-free algorithms can be closely bounded in terms of the average number of steps required until an operation completes. To the best of our knowledge, this is the first attempt to analyze progress conditions, typically stated in relation to a worst-case adversary, in a stochastic model capturing their expected asymptotic behavior.}, author = {Alistarh, Dan-Adrian and Censor Hillel, Keren and Shavit, Nir}, journal = {Journal of the ACM}, number = {4}, publisher = {ACM}, title = {{Are lock free concurrent algorithms practically wait free }}, doi = {10.1145/2903136}, volume = {63}, year = {2016}, } @article{8020, abstract = {Balance of cortical excitation and inhibition (EI) is thought to be disrupted in several neuropsychiatric conditions, yet it is not clear how it is maintained in the healthy human brain. When EI balance is disturbed during learning and memory in animal models, it can be restabilized via formation of inhibitory replicas of newly formed excitatory connections. Here we assess evidence for such selective inhibitory rebalancing in humans. Using fMRI repetition suppression we measure newly formed cortical associations in the human brain. We show that expression of these associations reduces over time despite persistence in behavior, consistent with inhibitory rebalancing. To test this, we modulated excitation/inhibition balance with transcranial direct current stimulation (tDCS). Using ultra-high-field (7T) MRI and spectroscopy, we show that reducing GABA allows cortical associations to be re-expressed. This suggests that in humans associative memories are stored in balanced excitatory-inhibitory ensembles that lie dormant unless latent inhibitory connections are unmasked.}, author = {Barron, H.C. and Vogels, Tim P and Emir, U.E. and Makin, T.R. and O’Shea, J. and Clare, S. and Jbabdi, S. and Dolan, R.J. and Behrens, T.E.J.}, issn = {0896-6273}, journal = {Neuron}, number = {1}, pages = {191--203}, publisher = {Elsevier}, title = {{Unmasking latent inhibitory connections in human cortex to reveal dormant cortical memories}}, doi = {10.1016/j.neuron.2016.02.031}, volume = {90}, year = {2016}, } @inproceedings{8094, abstract = {With the accelerated development of robot technologies, optimal control becomes one of the central themes of research. In traditional approaches, the controller, by its internal functionality, finds appropriate actions on the basis of the history of sensor values, guided by the goals, intentions, objectives, learning schemes, and so forth. The idea is that the controller controls the world---the body plus its environment---as reliably as possible. This paper focuses on new lines of self-organization for developmental robotics. We apply the recently developed differential extrinsic synaptic plasticity to a muscle-tendon driven arm-shoulder system from the Myorobotics toolkit. In the experiments, we observe a vast variety of self-organized behavior patterns: when left alone, the arm realizes pseudo-random sequences of different poses. By applying physical forces, the system can be entrained into definite motion patterns like wiping a table. Most interestingly, after attaching an object, the controller gets in a functional resonance with the object's internal dynamics, starting to shake spontaneously bottles half-filled with water or sensitively driving an attached pendulum into a circular mode. When attached to the crank of a wheel the neural system independently discovers how to rotate it. In this way, the robot discovers affordances of objects its body is interacting with.}, author = {Martius, Georg S and Hostettler, Rafael and Knoll, Alois and Der, Ralf}, booktitle = {15th International Conference on the Synthesis and Simulation of Living Systems}, isbn = {9780262339360}, location = {Cancun, Mexico}, pages = {142--143}, publisher = {MIT Press}, title = {{Self-organized control of an tendon driven arm by differential extrinsic plasticity}}, doi = {10.7551/978-0-262-33936-0-ch029}, volume = {28}, year = {2016}, } @unpublished{8128, abstract = {The stimulus selectivity of synaptic currents in cortical neurons often shows a co-tuning of excitation and inhibition, but the mechanisms that underlie the emergence and plasticity of this co-tuning are not fully understood. Using a computational model, we show that an interaction of excitatory and inhibitory synaptic plasticity reproduces both the developmental and – when combined with a disinhibitory gate – the adult plasticity of excitatory and inhibitory receptive fields in auditory cortex. The co-tuning arises from inhibitory plasticity that balances excitation and inhibition, while excitatory stimulus selectivity can result from two different mechanisms. Inhibitory inputs with a broad stimulus tuning introduce a sliding threshold as in Bienenstock-Cooper-Munro rules, introducing an excitatory stimulus selectivity at the cost of a broader inhibitory receptive field. Alternatively, input asymmetries can be amplified by synaptic competition. The latter leaves any receptive field plasticity transient, a prediction we verify in recordings in auditory cortex.}, author = {Clopath, Claudia and Vogels, Tim P and Froemke, Robert C. and Sprekeler, Henning}, booktitle = {bioRxiv}, pages = {43}, publisher = {Cold Spring Harbor Laboratory}, title = {{Receptive field formation by interacting excitatory and inhibitory synaptic plasticity}}, year = {2016}, } @article{8241, abstract = {Background: Anticancer vaccines could represent a valuable complementary strategy to established therapies, especially in settings of early stage and minimal residual disease. HER-2 is an important target for immunotherapy and addressed by the monoclonal antibody trastuzumab. We have previously generated HER-2 mimotope peptides from phage display libraries. The synthesized peptides were coupled to carriers and applied for epitope-specific induction of trastuzumab-like IgG. For simplification and to avoid methodological limitations of synthesis and coupling chemistry, we herewith present a novel and optimized approach by using adeno-associated viruses (AAV) as effective and high-density mimotope-display system, which can be directly used for vaccination. Methods: An AAV capsid display library was constructed by genetically incorporating random peptides in a plasmid encoding the wild-type AAV2 capsid protein. AAV clones, expressing peptides specifically reactive to trastuzumab, were employed to immunize BALB/c mice. Antibody titers against human HER-2 were determined, and the isotype composition and functional properties of these were tested. Finally, prophylactically immunized mice were challenged with human HER-2 transfected mouse D2F2/E2 cells. Results: HER-2 mimotope AAV-vaccines induced antibodies specific to human HER-2. Two clones were selected for immunization of mice, which were subsequently grafted D2F2/E2 cells. Both mimotope AAV clones delayed the growth of tumors significantly, as compared to controls. Conclusion: In this study, a novel mimotope AAV-based platform was created allowing the isolation of mimotopes, which can be directly used as anticancer vaccines. The example of trastuzumab AAV-mimotopes demonstrates that this vaccine strategy could help to establish active immunotherapy for breast-cancer patients.}, author = {Singer, Josef and Manzano-Szalai, Krisztina and Fazekas, Judit and Thell, Kathrin and Bentley-Lukschal, Anna and Stremnitzer, Caroline and Roth-Walter, Franziska and Weghofer, Margit and Ritter, Mirko and Pino Tossi, Kerstin and Hörer, Markus and Michaelis, Uwe and Jensen-Jarolim, Erika}, issn = {2162-402X}, journal = {OncoImmunology}, number = {7}, publisher = {Taylor & Francis}, title = {{Proof of concept study with an HER-2 mimotope anticancer vaccine deduced from a novel AAV-mimotope library platform}}, doi = {10.1080/2162402x.2016.1171446}, volume = {5}, year = {2016}, }