Long-lasting positive effects of collaborative remembering on false assents to misleading questions

Previous studies showed that collaborative remembering can reduce false memories through a process of mutual error checking, although conclusions were limited by the nature of the memory tasks (very few errors). The present experiments extend these findings to eyewitness memory by using a paradigm designed to increase the frequency of memory errors. Collaborative and nominal pairs viewed a video-clip illustrating a bank robbery, provided an immediate free recall, were forced to confabulate answers to false-event questions, and, after a short- (1 h: Experiment 1) or a long-term delay (1 week: Experiment 2), were administered a yes/no recognition task in which the misleading statements either matched the questions presented in the confabulation phase (answered questions) or not (control questions). Collaborative pairs recalled fewer correct details in the immediate free recall task, replicating the negative effects of collaborative inhibition. Most importantly, in the final recognition test, collaborative pairs were less likely to provide false assents to misleading statements, regardless of whether they had provided a response to the related false-event questions 1 h or 1 week earlier. Our results suggest that collaboration can increase the eyewitnesses' tendency to check the accuracy of others' responses and reject false memories through discussion

The attentional boost effect in young and adult euthymic bipolar patients and healthy controls

In the Attentional Boost Effect (ABE), stimuli encoded with to-be-responded targets are later recognized more accurately than stimuli encoded with to-be-ignored distractors. While this effect is robust in young adults, evidence regarding healthy older adults and clinical populations is sparse. The present study investigated whether a significant ABE is present in bipolar patients (BP), who, even in the euthymic phase, suffer from attentional deficits, and whether the effect is modulated by age. Young and adult euthymic BP and healthy controls (HC) presented with a sequence of pictures paired with target or distractor squares were asked to pay attention to the pictures and press the spacebar when a target square appeared. After a 15-min interval, their memory of the pictures was tested in a recognition task. The performance in the detection task was lower in BP than in HC, in both age groups. More importantly, neither young nor adult BP exhibited a significant ABE; for HC, a robust ABE was only found in young participants. The results suggest that the increase in the attentional demands of the detection task in BP and in adult HC draws resources away from the encoding of target-associated stimuli, resulting in elimination of the ABE. Clinical implications are discussed

The Relativistic Fe Emission Line in XTE J1650-500 with BeppoSAX: Evidence for Black Hole Spin and Light Bending Effects?

We report spectral results from three BeppoSAX observations of the black hole candidate XTE J1650-500 during its 2001/2002 outburst. We find strong evidence for the presence of a broad and strongly relativistic Fe emission line. The line profile indicates an accretion disc extending down to two gravitational radii (or less) suggesting the presence of a rapidly rotating central Kerr black hole. Thanks to the broadband spectral coverage of BeppoSAX, we could analyze the 1.5-200 keV spectra of the three observations and report the presence of a strong reflection component from the accretion disc, which is totally consistent with the observed broad Fe emission line. The shape of the reflection component appears to be affected by the same special and general relativistic effects that produce the broad Fe line. We study the variation of the different spectral components from the first to the third observation and we find that they are well reproduced by a recently proposed light bending model.Comment: Minor changes in text and in Figures/Tables. Section 3.1.2 added. Accepted by MNRA

The Similarity of Broad Iron Lines in X-ray Binaries and Active Galactic Nuclei

We have compared the 2001 XMM-Newton spectra of the stellar mass black hole binary XTE J1650-500 and the active galaxy MGC-6-30-15, focusing on the broad, excess emission features at ~4--7 keV displayed by both sources. Such features are frequently observed in both low mass X-ray binaries and active galactic nuclei. For the former case it is generally accepted that the excess arises due to iron emission, but there is some controversy over whether their width is partially enhanced by instrumental processes, and hence also over the intrinsic broadening mechanism. Meanwhile, in the latter case, the origin of this feature is still subject to debate; physically motivated reflection and absorption interpretations are both able to reproduce the observed spectra. In this work we make use of the contemporaneous BeppoSAX data to demonstrate that the breadth of the excess observed in XTE J1650-500 is astrophysical rather than instrumental, and proceed to highlight the similarity of the excesses present in this source and MGC-6-30-15. Both optically thick accretion discs and optically thin coronae, which in combination naturally give rise to relativistically-broadened iron lines when the disc extends close to the black hole, are commonly observed in both class of object. The simplest solution is that the broad emission features present arise from a common process, which we argue must be reflection from the inner regions of an accretion disc around a rapidly rotating black hole; for XTE J1650-500 we find spin constraints of 0.84 < a* < 0.98 at the 90 per cent confidence level. Other interpretations proposed for AGN add potentially unnecessary complexities to the theoretical framework of accretion in strong gravity.Comment: Accepted for publication in MNRAS; 22 pages, 17 figure

Regulation of Cyclooxygenase-2 Expression by Heat: A Novel Aspect of Heat Shock Factor 1 Function in Human Cells

The heat-shock response, a fundamental defense mechanism against proteotoxic stress, is regulated by a family of heat-shock transcription factors (HSF). In humans HSF1 is considered the central regulator of heat-induced transcriptional responses. The main targets for HSF1 are specific promoter elements (HSE) located upstream of heat-shock genes encoding cytoprotective heat-shock proteins (HSP) with chaperone function. In addition to its cytoprotective function, HSF1 was recently hypothesized to play a more complex role, regulating the expression of non-HSP genes; however, the non-canonical role of HSF1 is still poorly understood. Herein we report that heat-stress promotes the expression of cyclooxygenase-2 (COX-2), a key regulator of inflammation controlling prostanoid and thromboxane synthesis, resulting in the production of high levels of prostaglandin-E2 in human cells. We show that heat-induced COX-2 expression is regulated at the transcriptional level via HSF1-mediated signaling and identify, by in-vitro reporter gene activity assay and deletion-mutant constructs analysis, the COX-2 heat-responsive promoter region and a new distal cis-acting HSE located at position −2495 from the transcription start site. As shown by ChIP analysis, HSF1 is recruited to the COX-2 promoter rapidly after heat treatment; by using shRNA-mediated HSF1 suppression and HSE-deletion from the COX-2 promoter, we demonstrate that HSF1 plays a central role in the transcriptional control of COX-2 by heat. Finally, COX-2 transcription is also induced at febrile temperatures in endothelial cells, suggesting that HSF1-dependent COX-2 expression could contribute to increasing blood prostaglandin levels during fever. The results identify COX-2 as a human non-classical heat-responsive gene, unveiling a new aspect of HSF1 function

Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B -> K(*) l+ l-

In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Comment: 16 pages, 14 figures, accepted by Phys. Rev.

Measurement of B(B-->X_s {\gamma}), the B-->X_s {\gamma} photon energy spectrum, and the direct CP asymmetry in B-->X_{s+d} {\gamma} decays

The photon spectrum in B --> X_s {\gamma} decay, where X_s is any strange hadronic state, is studied using a data sample of (382.8\pm 4.2) \times 10^6 e^+ e^- --> \Upsilon(4S) --> BBbar events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B --> X_s \gamma) = (3.21 \pm 0.15 \pm 0.29 \pm 0.08)\times 10^{-4} and the first, second, and third moments = 2.267 \pm 0.019 \pm 0.032 \pm 0.003 GeV,, )^2> = 0.0484 \pm 0.0053 \pm 0.0077 \pm 0.0005 GeV^2, and )^3> = -0.0048 \pm 0.0011 \pm 0.0011 \pm 0.0004 GeV^3, for the range E_\gamma > 1.8 GeV, where E_{\gamma} is the photon energy in the B-meson rest frame. Results are also presented for narrower E_{\gamma} ranges. In addition, the direct CP asymmetry A_{CP}(B --> X_{s+d} \gamma) is measured to be 0.057 \pm 0.063. The spectrum itself is also unfolded to the B-meson rest frame; that is the frame in which theoretical predictions for its shape are made.Comment: 37 pages, 19 postscript figures, submitted to Phys. Rev. D. No analysis or results have changed from previous version. Some changes to improve clarity based on interactions with Phys. Rev. D referees, including one new Figure (Fig. 13), and some minor wording/punctuation/spelling mistakes fixe

Measurement of CP Asymmetries and Branching Fractions in Charmless Two-Body B-Meson Decays to Pions and Kaons

We present improved measurements of CP-violation parameters in the decays $B^0 \to \pi^+ \pi^-$, $B^0 \to K^+ \pi^-$, and $B^0 \to \pi^0 \pi^0$, and of the branching fractions for $B^0 \to \pi^0 \pi^0$ and $B^0 \to K^0 \pi^0$. The results are obtained with the full data set collected at the $\Upsilon(4S)$ resonance by the BABAR experiment at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory, corresponding to $467 \pm 5$ million $B\bar B$ pairs. We find the CP-violation parameter values and branching fractions $S_{\pi^+\pi^-} = -0.68 \pm 0.10 \pm 0.03, C_{\pi^+\pi^-} = -0.25 \pm 0.08 \pm 0.02, A_{K^-\pi^+} = -0.107 \pm 0.016 ^{+0.006}_{-0.004}, C_{\pi^0\pi^0} = -0.43 \pm 0.26 \pm 0.05, Br(B^0 \to \pi^0 \pi^0) = (1.83 \pm 0.21 \pm 0.13) \times 10^{-6}, Br(B^0 \to K^0 \pi^0) = (10.1 \pm 0.6 \pm 0.4) \times 10^{-6},$ where in each case, the first uncertainties are statistical and the second are systematic. We observe CP violation with a significance of 6.7 standard deviations for $B^0 \to\pi^+\pi^-$ and 6.1 standard deviations for $B^0 \to K^+ \pi^-$, including systematic uncertainties. Constraints on the Unitarity Triangle angle $\alpha$ are determined from the isospin relations among the $B \to \pi\pi$ rates and asymmetries. Considering only the solution preferred by the Standard Model, we find $\alpha$ to be in the range $[71^\circ,109^\circ]$ at the 68% confidence level.Comment: 18 pages, 11 postscript figures, submitted to Phys. Rev.

Cross Sections for the Reactions e+e- --> K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation Events

We study the processes e+e- --> K+ K- pi+pi-gamma, K+ K- pi0pi0gamma, and K+ K- K+ K-gamma, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb-1 of BaBar data. The invariant mass of the hadronic final state defines the \epem center-of-mass energy, so that the K+ K- pi+pi- data can be compared with direct measurements of the e+e- --> K+ K- pi+pi- reaction. No direct measurements exist for the e+e- --> K+ K-pi0pi0 or e+e- --> K+ K-K+ K- reactions, and we present an update of our previous result with doubled statistics. Studying the structure of these events, we find contributions from a number of intermediate states, and extract their cross sections. In particular, we perform a more detailed study of the e+e- --> phi(1020)pipigamma reaction, and confirm the presence of the Y(2175) resonance in the phi(1020) f0(980) and K+K-f0(980) modes. In the charmonium region, we observe the J/psi in all three final states and in several intermediate states, as well as the psi(2S) in some modes, and measure the corresponding product of branching fraction and electron width.Comment: 35 pages, 42 figure

Precise Measurement of the e+ e- --> pi+ pi- (gamma) Cross Section with the Initial-State Radiation Method at BABAR

A precise measurement of the cross section of the process $e^+e^-\to\pi^+\pi^-(\gamma)$ from threshold to an energy of 3GeV is obtained with the initial-state radiation (ISR) method using 232fb$^{-1}$ of data collected with the BaBar detector at $e^+e^-$ center-of-mass energies near 10.6GeV. The ISR luminosity is determined from a study of the leptonic process $e^+e^-\to\mu^+\mu^-(\gamma)\gamma_{\rm ISR}$, which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process $e^+e^-\to\pi^+\pi^-(\gamma)$ is obtained with a systematic uncertainty of 0.5% in the dominant $\rho$ resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured $\pi\pi$ cross section from threshold to 1.8GeV is $(514.1 \pm 2.2({\rm stat}) \pm 3.1({\rm syst}))\times 10^{-10}$.Comment: 58 pages, 56 figures, to be submitted to Phys. Rev.